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Infrared Spectrometry

Infrared Spectrometry

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Infrared spectrometry is an analytical technique used to identify and quantify materials based on their absorption of infrared radiation. It measures the vibrational transitions of molecular bonds, providing a spectrum that reflects the molecular structure and functional groups present in a sample.
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Infrared spectrometry is an analytical technique used to identify and quantify materials based on their absorption of infrared radiation. It measures the vibrational transitions of molecular bonds, providing a spectrum that reflects the molecular structure and functional groups present in a sample.

Key research themes

1. How can infrared imaging spectrometry and spectroscopic techniques be optimized for material identification and surface characterization?

This theme addresses advancements in imaging spectrometry and IR spectroscopy methods aimed at enhancing the specificity and accuracy of material identification—especially minerals, surface materials, and complex mixtures—via finely resolved spectral data acquisition and analysis. The goal is to overcome historical limitations associated with spectral resolution, sensor design, and data processing to enable reliable, remote, and in situ identification of materials based on their infrared spectral signatures.

Imaging Spectrometry for Earth Remote Sensing
by engin çetin

2016

Key finding: Demonstrated that imaging spectrometry acquiring 100-200 contiguous spectral bands in the 0.4 to 2.5 µm range enables direct and remote identification of surface materials via diagnostic absorption features as narrow as 20-40... Read more
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Mineral Physicochemistry Underlying Feature-Based Extraction of Mineral Abundance and Composition from Shortwave, Mid and Thermal Infrared Reflectance Spectra
by Carsten Laukamp

2021, Minerals

Key finding: Provided a comprehensive physicochemical and vibrational mode framework for interpreting mineral absorption features across SWIR, MIR, and TIR ranges, establishing relationships between absorption band position, intensity,... Read more
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Imaging Spectrometry for Earth Remote Sensing
by engin çetin

2016

Key finding: Outlined technological advances in sensor optics and detector arrangements, linking multispectral sensors (e.g., Landsat TM) to new imaging spectrometry systems using line array detectors that provide increased residence time... Read more
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2. What are the prospects and challenges of miniaturizing handheld near-infrared spectrometers for in-field applications?

This theme explores the rapid development, performance evaluation, and application landscape of miniaturized and handheld near-infrared spectrometers (NIR). Emphasis is placed on instrumentation design principles, trade-offs from miniaturization on analytical performance, realistic application scopes in materials and food control, and ongoing concerns regarding the robustness and reliability of these portable spectrometers outside laboratory environments.

Handheld Near-Infrared Spectroscopy: State-of-the-Art Instrumentation and Applications in Material Identification, Food Authentication, and Environmental Investigations
by Isao Noda

2023, Chemosensors

Key finding: Reviewed instrumental design strategies enabling NIR spectrometer miniaturization down to ~100g devices with cost reductions below USD 1000, highlighting that contemporary handheld NIR devices achieve analytical performance... Read more
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Handheld near-infrared spectrometers: Where are we heading?
by Justyna Grabska

2021, NIR news

Key finding: Analyzed the degrees of miniaturization achieved in NIR devices, emphasizing the trade-offs between size reduction and performance, especially sensor sensitivity and chemical specificity. Highlighted the technology’s... Read more
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Handheld Near-Infrared Spectroscopy: State-of-the-Art Instrumentation and Applications in Material Identification, Food Authentication, and Environmental Investigations
by Isao Noda

2023, Chemosensors

Key finding: Discussed the underlying chemical information captured in NIR spectra (combination and overtone bands of C-H, O-H, N-H, etc.), noting their lower intensity relative to fundamental MIR bands but practical advantages such as... Read more
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3. How can coherent mid-infrared frequency comb generation using silicon waveguides advance sensitive molecular spectroscopy?

This theme covers recent advancements in integrated photonics for mid-infrared (mid-IR) spectroscopy, focusing on silicon-on-sapphire nanophotonic waveguide designs engineered to produce coherent, broadband frequency combs spanning key molecular absorption bands. It addresses leveraging precise geometrical dispersion control for tailored spectral shaping, noise characterization, and demonstration of functional dual-comb spectroscopy for gas sensing applications.

Versatile silicon-waveguide supercontinuum for coherent mid-infrared spectroscopy
by Henry Timmers

2023, APL Photonics

Key finding: Developed offset-free mid-IR frequency combs through supercontinuum generation using silicon-on-sapphire waveguides with tailored dispersion profiles, achieving coherently broadened spectra spanning 2.5 to 6.2 µm with low... Read more
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All papers in Infrared Spectrometry

Polyethylene characterization by FTIR
by Paulo Roberto Janissek

2002, Polymer Testing

Important experimental parameters for FTIR spectra acquisition were studied: apodization, beam aperture, number of scans and spectral resolution, using polyethylene samples. The optimum conditions for the analyses were established and... more
Fig. 1. (A) reference acquisition under atmospheric conditions. (B) reference acquisition under reduced pressure (<4 hPa). (C) sample acquisition under reduced pressure (<4 hPa).
Fig. 2. Doublet in the region 1473-1463 cm~! for LDPE showing the effect of resolution.
Fig. 3. Influence of resolution on band intensity, for Bartlet apodization (triangular) for de doublet 1473-1463 cm~!.
Fig. 4. Base line spectrum used for the analysis of signal to noise ratio. Range correspondent to LDPE bands at 1473-1463 cm7!.
Fig. 5. Noise amplitude in the 1473-1463 cm7! range, for the different apodizations.
Fig. 8. LDPE spectra acquired by transmission (film) (A) and by ATR (sheet) (B), showing antioxidant absorptions (circled regions). Fig. 7. LDPE spectra acquired by different FTIR techniques: (A) transmission — film; (B) transmission — KBr disk and (C) ATE obtained with ZnSe and 45° incidence beam.
Fig. 9. Polyethylene spectra (film form). (a) Full range; (b) magnification of the 1300-1400 cm~! range.
Characteristics of the diverse techniques for polyethylene analysis by FTIR Table 1
Main absorptions of polyethylene in the IR region and their assignment upon the absorption bands within the measured spectra. In order to measure the influence of the available apodiz- ation types in the software, the noise amplitudes were estimated, taking the most intense minimum and maximum points of the baseline (without sample), in the regions where the PE bands are located and taking the difference between them, as shown in Fig. 4. In Fig. 5 the results from calculations made for each of the four apodization types are shown. It was noted that Bartlet apodization (triangular) afforded the lowest noise level, and was thus adopted in all the analyses. Table 2
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Synthesis, spectral characterization, in vitro antibacterial, antifungal and cytotoxic activities of Co (II), Ni (II) and Cu (II) complexes with 1, 2, 4-triazole Schiff bases
by Gangadhar B Bagihalli

2008, European journal of …

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Chemical and mechanistic aspects of the selective catalytic reduction of NO x by ammonia over oxide catalysts: A review
by Guido Busca

1998, Applied Catalysis B-environmental

The open literature concerning chemical and mechanistic aspects of the selective catalytic reduction of NO by ammonia (SCR process) on metal oxide catalysts is reviewed. Catalytic systems based on supported V 2 O 5 (including the... more
Scheme 1. Proposed structures for monomeric vanadyl species [46-49] and polymeric metavanadate species [51] in their dehydrated forms on the surface of VO5-TiO> catalysts.
Fig. 1. NO conversion versus temperature over: (a) WO3(9)/TiO3; (b) V205(0.78)/TiO2; (c) V205(1.4)/TiO2; (d) V205(0.78)-WO3(9)/TiO2; (e) V205(1.4)-WO3(9)/TiO>. Experimental conditions: catalyst weight, 160 mg (60-100 mesh); P=1 atm; flow rate=60 Ncc/min; feed: He+800 ppm NH3+800 ppm NO +1% O32. Reprinted with permission from [14].
Fig. 2. (A) Concentration profiles of NO, NH3, N2 and N2O over the V20s;-WO3-TiO; catalyst at a space velocity of 7.41 g! h—!. The inlet concentration of NO and NH; are 500 Vppm; balance He with 2% O>. (B) Concentration profiles of NO, NH3, Nz and NO over the Fe,03— SiO, catalyst at a space velocity of 1601 g~' h”!. The inlet concentration of NO and NH; are 500 Vppm; balance He with 2% O5. Reprinted with permission from [91]. tract the reactant NH; (the case of reactions (7) and
Fig. 3. Comparison of the conversion of NO in copper samples (%%wt CuO) on various oxide supports. Reprinted with permission from [95]. Several kinetic studies, mostly obtained under “real’’ conditions, have been reported for the SCR reaction. These are based on both merely empirical expressions (e.g. power-law kinetics) and/or mechan- istic approaches (e.g. Langmuir—Hinshelwood or The same features have been reported on catalysts with different active cations [12] like, e.g. on Mn- based catalysts (MnO,—AlO3, MnO,-WO3-AlLO3 [26,96] and MnO,-TiO>, [79]), on a number of Cu- expressions (e.g. power-law kinetics) and/or mechan- Parallel behaviors, with a temperature range with maximum NO conversion upon SCR and the competi- tion of SCR and ammonia oxidation reactions, have been found on any vanadia-based catalyst, like for V,05-ZrO, catalysts [93]. However, very similar behavior has also been reported for catalysts with very different formulations. In Fig. 2, a comparison is shown between the behavior of a V30;-WO3-TiO, catalyst and a Fe.O3—SiO, catalyst [91]. Again, this behavior can be found for supported CuO-based catalysts [12,21,94,95], as shown in Fig. 3.
Fig. 4. FT-IR spectra of the adsorbed species arising from adsorp- tion of ammonia over a V,0;-WO;/TiO2 sample (WO3=9% (w/w) and V,0; =1.47% (w/w)) and subsequent outgassing at RT (a), 400 K (b), 523 K (c), and 623 K (d). The spectra of the activated catalyst have been subtracted. Reprinted with permission from [133]. The thermal stability of NH3 adsorbed species has also been investigated by FTIR: it has been found that Lewis bonded molecular species are thermally more stable than ammonium ions (Fig. 4) [122]. It has also been reported that water competes with ammonia on
Scheme 2. Schemes of the generation of the Brgénsted acid sites from surface vanadyl centers.
Scheme 3. Proposed structures for ammonia adsorbed on V,0;—TiO3: (a) Lewis-bonded NH; at Ti sites; (b) H-bonded NH; on oxide sites; (c) Lewis-bonded NH3 at vanadyl sites; (d) ammonium ions bonded at V Br¢gnsted acid sites.
Fig. 5. FT-IR spectra of the adsorbed species arising from NH; adsorption (20 torr) over CuO-TiO, at (a) r.t. and subsequent outgassing at (b) 373 K, (c) 423 K, (d) 523 K, and (e) 623 K. Reprinted with permission from [19]. G. Busca et al./Applied Catalysis B: Environmental 18 (1998) 1-36
Fig. 6. FT-IR spectra of the adsorbed species arising from the interaction of NO (10 torr) with adsorbed ammonia on a model V205;-WO3-— TiO, catalyst, at different temperatures: (a) 300 K; (b) 373 K; (c) 403 K; (d) 423 K; (e) 453 K; (f) 523 K.
Fig. 7. Results of transient response experiments performed at 493 K over a V20s;-WO;/TiO> sample (WO3=9% (w/w) and V205=1.47% (w/ w)). Section (A): outlet reactor concentration following a step addition of NO (700 ppm) in He+1% Op, (squares) and of NH; (700 ppm) in He+1% Op (triangles). The theoretical inlet step is also reported (dashed line). Section (B): outlet reactor concentrations following a step addition of NH3 (700 ppm) in He+NO (700 ppm)-+O, 1%. The N, and H,O concentrations have not been reported. Section (C): outlet reactor concentrations following a step addition of NO (700 ppm) in He+NHs3 (700 ppm)+O, 1%. The Nz and HO concentrations have not been reported.
Fig. 8. Mechanism of the NO—NH; reaction on vanadium oxide catalysts proposed by Inomata et al. [68] in the presence of oxygen. Reprinted with permission from [68](c).
Fig. 9. Mechanism of the NO-—NH; reaction on supported vanadium oxide catalysts proposed by Janssen et al. [71](b) in the presence of oxygen. Reprinted with permission from [71](b).
Fig. 10. Mechanism of the NO—NH3 reaction on vanadium oxide catalysts proposed by Ozkan et al. [73](b) in the presence of oxygen.
Fig. 11. Mechanism of the NO-—NH; reaction on supported vanadium oxide catalysts proposed by Ramis et al. [123] in the presence of oxygen.
Fig. 12. Scheme illustrating the catalytic cycle of the SCR reaction over vanadia/titania catalyst in the presence of oxygen proposed by Topsge et al. [173]. Reprinted with permission from [173](c).
Fig. 13. Scheme illustrating the catalytic cycle of the SCR reaction over Cu-ZSM5 catalyst in the presence of oxygen proposed by Komatsu et al. [29]. Reprinted with permission from [29].
Fig. 14. Scheme illustrating the mechanism of the NO—NHs3 reaction over Cu-based catalyst in the presence of oxygen proposed by Centi et : [21]. Reprinted with permission from [21]. where NH species are produced by NH; dissociation. This mechanism is, however, only tentative since it is
Proposed reactant species, intermediates and active sites in different mechanisms and/or kinetic schemes for SCR on vanadia-based catalysts Table |
Proposed reactant species, intermediates and active sites in different mechanisms and/or kinetic schemes for SCR on vanadia-based catalysts Table 2
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Asymmetric least squares for multiple spectra baseline correction
by Silong Peng

2010, Analytica Chimica Acta

In this paper, based on asymmetric least squares smoothing, a new algorithm for multiple spectra baseline correction is proposed. By means of the similarity among the multiple spectra, the algorithm estimates the baselines by penalizing... more
The above framework shows certain relations with multipli- cation scattering correction (MSC). From the first term on the right side of Eq. (2), it can be seen that each corrected spectrum must be close to the mean corrected spectrum. MSC also corrects each spectrum according to the mean spectrum. While MSC does scatter correction on original spectrum, and our algorithm can simultaneously correct scatter effects and eliminate baselines (or trends). Up to aconstant factor m, the optimization problem (1) is equiv- alent to the following problem (see the proof in Appendix): The first term on the right side of Eq. (1) reflects the pairwise differences between the corrected spectra, while the second term measures the fitting error to the data as an asymmetric way and the last term is smoothness constraint of the baselines. When all regularization matrices Q; are chosen as the identity matrix (or p=0.5) in Eq. (1), the optimization framework (1) is actually a joint Hodrick-Prescott filtering algorithm which can extract the trends of multiple NIR spectra.
where Dis the second order differential matrix, each Q; is a diagonal matrix with diagonal elements w;,(j) = p ify;(j) > z;(j) and w;(j)=1—p otherwise, and A, jz; are regularization parameters. The goal of multiple spectra baseline correction algorithm is to learn baselines that perform well on the corresponding spectra, and then “co-regularize” the choices by penalizing disagreements among the baseline corrected spectra based on asymmetric least squares. Assume that m spectra yj, y2, ..., Ym are column vectors of length n, and zj, Z>, ..., Zm are the corresponding baselines to be estimated. The multiple spectra regularization solves the following optimization problem for k=1,...,m:
where a, is a relaxation factor, which reflects the similarity between the corresponding corrected spectrum and the mean cor- rected spectrum. Unlike Eq. (2), however, each corrected spectrum needs to be close to the mean corrected spectrum in the sense of a scale factor. to the following form:
Fig. 1. (a) Original spectrum; (b) two synthetic spectra with different baselines. Fig. 2. (a) Two true baselines (solid lines) and estimated baselines (dotted lines); (b) two relaxation factors.
With a simulation, the performance of multiple spectra base- line correction algorithm in a situation where there are two spectra with known baselines is presented. Assume original spectrum be of 8 Gaussian peaks with different widths, and two synthetic base- lines are added to it, yielding two drifted spectra shown in Fig. 1, The programs are written in house in Matlab Version R2008a (The MathWorks, Inc.) and run in a personal computer with an
Fig. 3. (a) Two spectra (solid lines) and estimated baselines (dashed lines); (b) two corrected spectra. Multiple spectra baseline correction algorithm on two real spec- tra selected from Dataset 1 is shown in Fig. 3, where parameters are selected as follows: A=100, 441 =10!°, w2=109, and p=10~. After baseline correction, two spectra are almost the same. It takes three seconds to estimate baselines of the 32 liquor spectra in Dataset 1, where each spectrum has length 3351. Fig. 4 shows the estimated baselines of 32 liquor spectra and baseline corrected spectra, where p=10~4, 4=500, and all the regularization parameters ju, are just set to be 10!! for simplicity. It can be seen from Figs. 3 and 4 that the baselines are nearly removed and the spectra scatterings around 3400 and 700cm~! are almost removed at the same time. INIViVUL — V 2 {NONE TT RVE]] AO RMILIPULOU, VWVLIRIR LGM ae CAI Loli” mated baseline and true baseline respectively. After coarse tuning in the first step, parameters (p, {1) corresponding to the minimum RMSE are chosen, then fine tuning is performed around p and jZ. Finally, parameters are chosen as follows: p=10~4, w=4 x 10° for spectrum y;, and p=10~4, =9 x 10° for spectrum yp. The fitting errors are shown in Table 1, where RMSE1 (RMSE2) is the error between the estimated baseline z; (z2) and true baseline b; (b2), and RMSE is the error between two baseline corrected spectra. It
Fig. 4. (a) 32 spectra (gray lines) and estimated baselines (black lines); (b) corrected spectra.
Fig. 5. (a) NIR spectra of corn samples (gray line) and estimated baselines (black line); (b) corrected spectra; (c) relaxation factors
Up toa constant factor m in the regularization parameters A and jL,, the Eqs. (6) and (7) are equivalent. Thus, it proves the equivalence between the optimization framework (1) and (2). Taking the partial derivative of Sz with respect to Z,,
The error between estimate baseline and true baseline. Table 1 can be seen from the table that multiple spectra baseline correc- tion algorithm outperforms AsLS for single spectrum, and makes the differences between corrected spectra smaller. Due to the joint regularization in multiple spectra baseline correction, the newly learned baseline may provide new information for the baseline to be estimated to improve its performance. Therefore, the per- formance of multiple spectra regularization is often significantly better than that of single spectrum approach.
The values in parentheses refer to the number of latent variables. No = original spectra, DT = Detrending based on second order polynomial fitting, MSBC = multiple spectr. baseline correction. Calibration regression statistics for SNV, MSC, DT and MSBC transforms on mp5. Table 2
[he values in parentheses refer to the number of latent variables. No = original spectra, DT = Detrending based on second order polynomial fitting, MSBC = multiple spect oaseline correction. Calibration regression statistics for SNV, MSC, DT and MSBC transforms on mp6. Table 3
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Chemical composition of the essential oil of marjoram (Origanum majorana L.) from Reunion Island
by J. Chane-Ming

1999, Food Chemistry

Capillary gas chromatography, mass and FTIR spectrometry were used to analyse the composition of the water-distilled essential oil of marjoram (Origanum majorana L.) grown in Reunion Island located in Indian Ocean (21 S 55 E). Among 45... more
Percentage composition of the essential oil of Origanum majorana L. * Tentative identification from mass spectra data; tr, trace (<0.02%); R.I., retention indices. Table 1
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Amide modes and protein conformation.
by Jagdeesh Bandekar

1992, Biochimica et biophysica acta

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FTIR study of polycaprolactone chain organization at interfaces
by Tamara Elzein

2004, Journal of Colloid and Interface Science

Polycaprolactone (PCL), extensively known as a biomaterial, is the subject of this paper. Knowing well that some biomaterial applications exhibit specific chain organization, we focused our study on the orientation of PCL chains when this... more
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Analytical strategies for the quality assessment of recycled high-impact polystyrene: A combination of thermal analysis, vibrational spectroscopy, and chromatography
by Francisco Vilaplana

2007, Analytica Chimica Acta

Oxidation temperature (T,x) and oxidation induction time (OIT) for high-im- pact polystyrene subjected to multiple processing and thermo-oxidative ageing at 90 °C
Figure 1.9. Proposed reactions for the oxidation of the PB-PS grafting sites scission of the PB-PS graft [45, 47, 54]. Further oxidation of the PS phase in PB-modified styrenic polymers is promoted by the free radicals formed during degradation of the rubber phase, compared to the oxidation of pure PS [47]. It is well known that the initiation of PS oxidation takes place by the oxygen attack to the a-hydrogens found on the backbone of the PS chain, leading to the formation of hydroperoxides as the initiation products [60, 61]. Aromatic and aliphatic ketones, peroxyesters, carboxylic acids, and anhydrides are some of the oxidised structures that can be found in PS subjected to thermo- and photo-oxidation; molecular compounds as benzoic acid, benzophenone, acetophenone, benzaldehyde, benzoic anhydride, and dibenzoylmethane are also formed as degradation products [60, 62, 63].
Figure 1.10. Chemical structures of the different families of brominated flame retardants The increasing environmental concern about BFRs is based on their persistence,
Figure 1.1. Plastic demand by end-use application sector in Western Europe, 2004 applicability of polymeric materials in wide markets [1]. Polymer demand in Western Europe has been continuously growing during the past decade, reaching a total demand volume of 43,50 million tonnes in 2004. In terms of end-use applications, packaging is by far the sector with highest polymer demand (37%), followed by building and construction applications (20%), automotive industry (7,5%) and electric and electronic equipment (7,5%); these results prove the versatility and applicability of polymeric materials in wide markets [1].
Figure 3.1 Procedure for modelling the life cycle of recycled plastics: a) modelling processing processing, service life and mechanical recycling by multiple processing and thermo- and mechanical recycling by multiple processing; b) modelling service life by thermo-oxidation.
Figure 1.7. Reaction mechanisms proposed for the PB phase during the thermo-and photo-
Glass transition temperatures (T,) of the polybutadiene (PB) and the polysty- rene (PS) phases of the high-impact polystyrene thermo-oxidised samples Table 2 related to the height of a reference peak at 1601 cm ', in order to make their results comparable and to eliminate the effect of the thickness of the films [6].
* Parameters calculated from the Fuoss—Kirkwood plot at a frequency of 1 Hz. Influence of multiple processing on the viscoelastic parameters related to the glass transition relaxations of PB and PS phases in HIP‘ according to the free-volume theory Table 1
Figure 1.8. Crosslinked gel structures after prolonged exposure of PB-modified styrenic polymer ether gel, and saturated gel structures [45, 54].
Figure 1.2. Plastic waste management options in terms of the life cycle of polymeric products The current environmental policy considers the material efficiency during service life and the reduction o f the environmental impact throughout their entire life cycle. Suitable waste management recovery options for plastic waste streams therefore contribute to the sustainable deve closing the mate opment of our societies taking into account a life cycle perspective, by rial and energetic life cycle loop and enhancing the conversion of waste materials into va uable resources (Fig. 1.2). The current environmental policy considers the material efficiency during service life and 1e dirrerent avaliable Options ror plastic waste recovery, 1n contraposition to lanadril sposal, include material recycling and energy recovery procedures. As a whole, recycling ocesses (mechanical and feedstock recycling) involve material recovery from plastic iste streams, whereas combustion procedures for heat production with controllec uissions are included into energy recovery options. Mechanical recycling consist: sically on the re-melting of plastic waste into new plastic products; this process can be tformed on homogeneous waste streams of on waste streams consisting on a mixture different plastic materials (mixed waste streams). By feedstock recycling, plastic waste: e cracked and depolymerised by chemical means into a series of petrochemica oducts or monomers, which can be later transformed again into new polymeri oducts by synthesis. Finally, energy recovery employs polymeric waste streams as fue ft energy production, since 1 tonne of plastic offers approximately the same amount o: ergy as 1 tonne of crude oil in the combustion process.
Figure 1.3. Evolution of plastic recovery options and total post-consumer plastic waste volume The rate of plastic waste recovery has been continuously increasing since the mid-90’s due to the implantation of mechanical recycling and energy recovery facilities all over Europe; feedstock recycling remains still as a minor alternative. As a result of thes developments and despite the increasing post-use plastic waste volumes, the amount o: residual waste sent to landfill disposal seems to have stabilised. Decoupling between th« volume of plastic consumption and the associated amount of residue generation i currently being achieved in the countries with a developed waste managemen infrastructure [1]. Figure 1.3 proves this progressive decoupling between the plastic wast growth and the volume sent to disposal, due to enhanced plastic waste recovery options. erowth and the volume sent to disposal, due to enhanced plastic waste recovery options. Analysing plastic recovery by end-use applications [3], the largest volume of recoverec plastic waste corresponds to municipal solid waste, with a total volume of 5.45 MTonne: in 2002. Sectors like agricultural applications exhibit the highest recovery rates (ove: 50%), though with lower waste volumes. However, the automotive sector and electrica and electronic equipment showed lower plastic recovery rates in 2002; this situation i: expected to be continuously improving due to the implementation of the corresponding European Directive 2000/53/EC on end-of-life vehicles ( 2002/96/EC on waste of electrical and electronic equipment (W/ ELV) and European Directiv Gb F) E). es es Analysing plastic recovery by end-use applications [3], the largest volume of recovered
Figure 1.4. Key properties for quality assessment of recycled plastics S a a“ * has lead to the identification of three key properties for the quality assessment of recycled plastics: the degree of mixing (composition), the degree of degradation and the presence of low molecular weight compounds (additives, degradation products, and contaminants) (Fig.1.4) [17]. These key properties are necessary to fully guarantee the applicability of recyclates for the manufacture of new products. The degree of mixing (composition) is related to the presence of polymeric impurities in the recycled polymers resulting from impure plastic waste streams and poor separation in the recycling plant. The degree of degradation of recyclates considers the degradation processes to which polymeric materials are subjected during their processing, service life, and further recovery. Finally, the identification of low molecular weight compounds (contaminants, additives, and degradation products) present in recycled polymers is essential to verify that the products are compliant with legislation on the presence of hazardous substances. that the products are compliant with legislation on the presence of hazardous substances.
Figure 1.5. Analytical strategies for degradation studies in polymers (drawn after [22]) degradation processes in polymers [22-24]. Different strategies can be considered to investigate the degree of polymer degradation, depending on the changes at a macroscopic or microscopic scale (Fig. 1.5) [22]. Common approaches to determine degradation effects include analysis of the alterations in chemical functional groups (using vibrational spectroscopy or nuclear magnetic resonance), crystallinity and thermal properties (using thermal analysis), morphology (using electron microscopy), mechanical properties (mechanical testing), and molecular weight distribution and composition (using size exclusion chromatography and mass spectroscopic techniques). Additionally, investigation of degradation products and additives using chromatographic tools have proved to be useful for monitoring ongoing degradation processes in polymers [22-24].
Figure 1.6. Microstructural isomeric units of polybutadiene The resulting material can be structurally defined as a multiphase system in which PE rubber granules are dispersed in a continuous rigid polystyrene (PS) matrix. The rubbe: phase contains the three typical microstructural isomeric units of PB: vinyl-1,2, cis-1,4 and trans-1,4 (Fig. 1.6). This multiphase structure confers HIPS its improved fracture resistance properties (impact strength, elongation at break, and fracture toughness together with a reduction in transparency, modulus and tensile strength if compared witk unmodified PS [43]. The introduction of a rubbery phase alters, however, the stability of the polymer blends towards degradation, enhancing the sensitivity of the material to the degradative agents. Degradation processes ate complex phenomena that usually involve different mechanisms and initiating agents, such as temperature, chemical agents, mechanical stress, or radiation. In this chapter a brief review on the degradation aspects related to HIPS and other rubber-modified styrenic polymers will be given, with special focus on photo-oxidative, thermo-oxidative and thermo-mechanical degradation.
II. Reactions of cis-1,4 and trans-1,4 isomers nvolves the creation of free radicals and the formation of hydroperoxides; the second stage includes the decomposition of the hydroperoxides and the formation of different oroducts containing oxidised groups. Further reactions are responsible for the formation of stable crosslinked structures, extensive damage in the polymeric chains by chain scission and the disunification of the polymer graft between butadiene and styrene units. Different reaction mechanisms have been proposed by several authors for the thermo- and photo-oxidation of PB-modified styrenic polymers (Fig. 1.7) [44, 45, 47, 52, 59].
Figure 3.2 Sampling of the HIPS materials through the large-scale mechanical recycling process 3.1.3 Reference HIPS samples containing brominated flame retardants
Figure 4.1. Influence of reprocessing on the melt mass-flow rate (MFR) of HIPS.
Figure 4.2. Tensile properties of the virgin HIPS subjected to multiple processing: a) tensile properties at break: (@) elongation at break; (9) stress at break; b) Young’s modulus. Figure 4.2. Tensile properties of the virgin HIPS subjected to multiple processing: a) tensile properties at break: (@) elongation at break; (©) stress at break; b) Young’s modulus. slightly more brittle material with lower ductility. The influence of reprocessing and thermo-oxidation on the mechanical properties (elastic modulus, elongation at break and stress at break) was analysed by tensile testing. Figure 4.2 shows the evolution of tensile properties during consecutive extrusion cycles. The elastic modulus remains practically unaffected; the stress and elongation at break are on the other hand clearly influenced by the successive processing steps, with a progressive diminution of the elongation at break and an increase of the stress at break. Each processing step induces the thermo-mechanical degradation of the HIPS materials, which may introduce alterations in the chemical structure of the polymeric chains, resulting in a slightly more brittle material with lower ductility.
detail from the results of vibrational spectroscopy and dynamic-mechanical analysis. As a conclusion, HIPS seems to be a promising material for mechanical recycling, sinc the processability of the recyclates is guaranteed by the small variation of the MFR after. large number of recycling steps. On the other hand, elongation at break appears as th mechanical property that should determine the second market application for HIP‘ recyclates. Reprocessing up to nine cycles does not affect to high extent the mechanica properties of HIPS, while thermo-oxidation at 90°C may be considered to be quite sever for the mechanical nronerties of HIPS As a conclusion, HIPS seems to be a promising material for mechanical recycling, since for the mechanical properties of HIPS.
Figure 4.4. Curve fitting of the virgin HIPS Raman spectra to 5 individual bands for the determination of the three individual PB conformers: 1550-1700cm-1 region.
Figure 4.5. Chemical changes induced by reprocessing on the structure of HIPS by vibrationa
carbonyl regions. Figure 4.6 shows the FTIR spectra for the HIPS samples subjected to thermo-oxidative ageing at 90°C through the hydroxyl region (between 3600 and 3100cm'), carbonyl region (between 1800 and 1620cm'), and the double bond region (between 1000 and 880cm"'). Thermo-oxidation induces, in contrast with the heterogeneous effects reported by reprocessing, quite progressive changes in the analyzed functional group indexes; a marked decrease in the unsaturated groups (trans-1,4 and vinyl-1,2 groups) can be observed employing FTIR, while broad bands appear both in the hydroxyl and the catbonyl regions.
Figure 4.7. Chemical changes induced by thermo-oxidation at 90°C on the structure of HIPS:
Figure 4.8. Isocronal representation of the storage modulus E’ (lower plot) and loss modulus maximum of the loss modulus, which is usually assumed as the glass transition where FE”, is the maximum of the loss modulus; ~ is the Fuoss-Kirkwood parameter;
Figure 4.10. SEM micrographs of HIPS samples: a) virgin HIPS: b) reprocessed HIPS (9 cycles); which show the evident deterioration of the morphology under thermo-oxidation. he complex effects of multiple processing and thermo-oxidation on the microstructure od morphology of HIPS can be verified in the micrograms obtained by scannin P sy 8 y 2 lectron microscopy (S| FM). The typical double phase distribution in HIPS can be bserved in virgin HIPS microgram (Fig. 4.10a) where the PB granules are dispersed in 1e PS matrix. The PB granules exhibit heterogeneous shapes with a particle size in the rder of 5-10 um. After multiple processing (Fig. 4.10b), shrinkage in the shape of the B granules can be observed together with a clear modification in the surface of the ranules; cracks, channels and wrinkles are also appreciated in the PS matrix. The rogressive effect of thermo-oxidation on the morphology of HIPS can be followed with 1e exposure time. For shorter exposure times (Fig. 4.10c), the PB granules seem tc rease and contract, showing a rough outer surface; for longer exposure times, however. B phase appears to have partially lost the granular microstructure, though smallet article can still be detected (Figure 4.10d). Cracks can be also observed in the PS matrix. ee
Figure 4.11. Total ion chromatogram (TIC) from the MAE extracts of virgin HIPS, HIPS
polypropylene contaminations, respectively, in these materials. The presence of mixed polymeric fractions as impurities in recycled polymeric material: clearly affects the macroscopic performance of recyclates. The employment of therma analysis is suitable for the characterisation of the properties of the material in the bulk Polymeric contaminations in the recycled materials were detected by DSC. Figure 4.12 shows the thermograms corresponding to the second heating segment for the differen HIPS samples, where it can be observed that all the samples exhibit the slope chang corresponding to the glass transition of the polystyrene phase at around 90°C. Smal melting peaks at temperatures of 120°C and/or 160°C can be observed, however, fo: samples HIPS2 and HIPS7, which indicate the presence of polyethylene anc polypropylene contaminations, respectively, in these materials.
Figure 4.13. FTIR spectra of the HIPS samples: a) hydroxyl region (3100-3600cm); b) carbonyl the vinyl-1,2 and trans-1,4 peaks in the recycled materials can be qualitatively observed. The regions corresponding to the hydroxyl group, the carbonyl groups, and the double bond groups from the PB phase corresponding to the peak of trans-1,4 and vinyl-1,2 groups were analyzed in detail employing FTIR. Figure 4.13 represents the absorbance spectra of the HIPS samples in the hydroxyl, carbonyl, and unsaturated regions. The recycled samples show, in general, higher absorbance in the hydroxyl and carbonyl regions than the virgin material, because of the presence of humidity and other oxidative moieties. Considering the unsaturated region from the PB phase, a general decrease of the vinyl-1,2 and trans-1,4 peaks in the recycled materials can be qualitatively observed.
Figure 4.14. FTIR functional group indexes (hydroxyl; carbonyl; trans-1,4; vinyl-1,2) figure 4.14 represents the FTIR hydroxyl, carbonyl, trans-1,4, and vinyl-1,2, functiona rroup indexes for the analysed HIPS samples. The diminution of the unsaturatec unctional groups (vinyl-1,2 and trans-1,4) and the increase of the hydroxyl and carbony rroups in the real recycling samples, compared to the virgin material, may prove th« »ccurrence of PB oxidation during previous life and recycling of HIPS, resulting in < wide variety of oxidised structures in the polymeric chains [44, 45, 53]. The calculation o: he hydroxyl, carbonyl, vinyl-1,2 and trans-1,4 indexes could therefore be employed tc verify the degree of degradation in recycled plastics and to assess the content o: insaturated groups in recycled HIPS. samples from the large-scale mechanical recycling process. Conventional Raman
Figure 4.15. Raman functional group indexes (vinyl-1,2; cis-1,4; trans-1,4) for the HIPS samples.
The presence of low molecular weight compounds in recycled HIPS was assessed by microwave-assisted extraction followed by analysis of the extracts using GC-MS. Figure 4.16 presents a total ion chromatogram (TIC) from the extract of recycled HIPS as ar example of the resulting chromatograms for the analysed materials. At a glance, differen zones can be observed: A first zone until approximately 800s where the volatile organic compounds (VOCs) appear; a second zone around 900s where styrene dimers (residue: from polymerisation) elute; a third zone around 1400s where different peaks from the styrene trimers (residues of polymerisation) appear; and, finally, a fourth zone at longer: elution times where different aliphatic compounds can be found. elution times where different aliphatic compounds can be found. Figure 4.16. Total lon Chromatogram (TIC) of the low molecular weight compounds extracted
The optimisation of the MS sensitivity was per formed by direct infusion of the standard analytes in acetonitrile into the APCI mass spectrometer. Figure 4.17 shows the full scan mass spectra of TBBPA, HBCD, and Deca-BDE. According to these fragmentation results, the MRM signals corresponding to m/z 543-79 and m/z 543-481 for TBBPA, m/z 641—+79 and m/z 641-81 for the three HBCD congeners, and m/z 487-79 and m/z 487-81 for Deca-BDE, were selected and compared in terms of LOD, LOQ and linearity, to detect and quantify the flame retard ant content in the extracts. linearity, to detect and quantify the flame retardant content in the extracts.
Figure 4.17. Full scan mass spectra of the BFRs acquired in the APCI negative mode by direct infusion of standard solutions in acetonitrile: a) TBBPA; b) HBCD; c) Deca-BDE.
Figure 4.18. Chromatogram for the superposed MRM signals corresponding to TBBPA
Figure 4.19. Comparison of the extraction yield of PLE, MAE, and PLE for the different BFRs
Figure 4.20 shows the chro The sample ABS-GVL2-07 BDE (tg=20.6 min), other minor peaks that may correspond with other PBDI es matograms of the extracts for the standard WEEE samples. shows, in addition to the main peak corresponding to Deca- UI congeners with lower bromination degree at tp=20.0 min, tg=19.4 min, and tg=18.9 min, either originally contained in the technical Deca-BDE grade used in the manufacture of the plastic component, or due to the debromination of the BFR during service life and further recycling (Figure 4.20a). Sample ABS-GVL2-11 shows a single clear peak corresponding with TBBPA at tz=11.1 min, proving that the flame retardant has been successfully extracted from the polymeric matrix (Figure 4.20b). Finally, different peaks can be observed in the chromatogram corresponding to sample SB-GVL2-07; the main peak assigned to Deca-BD] EH at tg=20.6 min and other peaks that may be attributed to other PBDE congeners at tp=19.9 min, tg=18.9 min, and tg=18.4 min (Figure 4.20c). other PBDE congeners at tg=19.9 min, tp=18.9 min, and th=18.4 min (Figure 4.20c).
Scheme 1. Procedure employed for the modelling of the second life for plastics, (a) modelling of processing and mechanical recycling; (b) modelling of service life.
Fig. 1. Influence of reprocessing on the melt mass-flow rate (MFR) of HIPS. From a recycling point of view, HIPS seems to be a prom- ising material for mechanical recycling, since the MFR values only increase approximately 2% in the first reprocessing step and a total of 45% after nine extrusion cycles. This small var- iation of the MFR with a large number of recycling steps would guarantee the processability of the recyclates during the mechanical recycling processes.
Fig. 2. Tensile properties of the virgin HIPS subjected to multiple processing, (a) tensile properties at break: (@) elongation at break; (O) stress at break; (t Young’s modulus.
Fig. 3. Tensile properties of the virgin HIPS subjected to thermo-oxidative ageing at 90 °C, (a) tensile properties at break: (@) elongation at break; (©) stress at break; (b) Young’s modulus. The absorbance spectra of the surface of the HIPS samples subjected to multiple processing and thermo-oxidative ageing at 90 °C were recorded and studied. In particular, the regions corresponding to the hydroxyl groups (between 3100 and 3600 cm—'), carbonyl groups (between 1620 and 1780 cm~'), and the unsaturated groups from the polybutadi- ene phase of HIPS corresponding to the peak of trans-1,4 (966 cm!) and vinyl-1,2 (911 cm ') were analyzed in detail. The peak corresponding to the cis-1,4 double bond group from the polybutadiene phase (around 730 cm ') could not be stud- ied because of the overlapping peak from the C—H out- of-plane vibration of the styrene units in polystyrene at 754 cm! [13]. Moreover, in order to obtain a quantitative pic- ture of the structural changes caused by reprocessing and age- ing, the relative absorbance ratios of the peaks corresponding to the maximum of the hydroxyl region (3287 cm™'), the max- imum of the carbonyl region (1729 cm™'), trans-1,4 group (965 cm_'), and vinyl-1,2 group (907 cm’) were determined, As a conclusion, the elongation at break appears to be the mechanical property that should determine the recycling pos- sibilities and the second-market application for high-impact polystyrene recyclates. It was observed that reprocessing up to nine cycles does not affect to any high extent the mechanical properties of HIPS, with a decrease of 15% in elongation at break after three extrusion steps, and a total decrease of around 38% in the elongation at break after nine cycles. On the other hand, the thermo-oxidative ageing at 90 °C may be considered to be quite severe for the mechanical properties of HIPS, since it remarkably affects the elongation at break values of HIPS, with a decrease of 85% after only 4 days of exposure.
Fig. 4. FTIR absorbance spectra at the region between 1800 and 1400 cm! for HIPS samples subjected to different steps of multiple processing. Fig. 5 represents the spectroscopic results of the analyzed functional group indexes as a function of the reprocessing steps. It can be observed that repeated processing steps induce
Fig. 5. Evolution of the (©) vinyl-1,2 ratio, (MB) trans-1,4 ratio, (A) carbonyl ratio and (@) hydroxyl ratio, with the reprocessing steps for HIPS. Pigs. O snOWS We WNTarea speCuld LOT UI FAIS sdliples suD- jected to thermo-oxidative ageing at 90 °C through the hy- droxyl region (between 3600 and 3100 cm’), carbonyl region (between 1800 and 1620 cm’!), and the double bond region (between 1000 and 880 cm7'). In addition, a quantita- tive study of the selected functional groups was performed and the evolution of their indexes with the ageing time was then plotted in Fig. 7. Figs. 6 and 7 demonstrate that thermo-oxida- tive ageing induces, in contrast with the heterogeneous effects reported by reprocessing, quite progressive changes in the an- alyzed functional group indexes. As a whole, thermo-oxidative ageing caused a marked decrease in the unsaturated groups (trans-1,4 and vinyl-1,2 groups), while broad bands appear both in the hydroxyl and the carbonyl regions. These results are in agreement with previous studies performed on the photo- and thermo-oxidation of HIPS and other styrene/buta- diene copolymers by FTIR spectroscopy [14—16]. The trans-1,4 group index showed a slight decrease at the initial ageing time due to the protective effect of the antioxidants, but after the fourth day of thermo-oxidative ageing, the reduc- tion was considerable. This phenomenon is in accordance with the results of Israeli et al. [14], which reported that the thermal oxidation of HIPS shows an induction period, followed by 9 fast oxidation of nolvbutadiene and then bv a slow oxidation
Fig. 7. Evolution of the (©) vinyl-1,2 ratio, (MB) trans-1,4 ratio, (A) carbonyl ratio and (@) hydroxy] ratio, with the time for HIPS subjected to thermo-ox- idative ageing at 90 °C.
Scheme 1. Polybutadiene microstructures: trans-1,4; cis-1,4; vinyl-1,2 groups.
Fig. 1. Curve-fitting of the virgin HIPS Raman spectra to five individual bands for the determination of the three individual PB conformers: 1550-1700 cm™! region.
Fig. 2. Raman spectra of the PB microstructure region of selected HIPS samples subjected to multiple processing. Fig. 2 shows the effect of multiple processing on polybutadiene microstructure in selected HIPS sam- ples; PB microstructure is, to some extent, affected by the repeated extrusion cycles, since the intensities of the bands slightly decrease with the successive reprocessing steps. The influence of multiple pro- cessing on the Raman indexes can be observed in Fig. 3; in general, the normalised areas for the three microstructures decrease slightly under the consecu- tive extrusion cycles. The thermo-mechanical degra- dation produced by the processing steps may induce chemical reactions in polybutadiene that could cause crosslinking of the rubber phase and alter
Fig. 4. Raman spectra of the PB microstructure region of selected HIPS samples subjected to thermo-oxidation.
Fig. 3. Raman functional group indexes for the PB microstruc- ture of HIPS subjected to multiple processing: (Ml) trans-1,4; (O) cis-1,4; (@) vinyl-1,2.
Fig. 5. Evolution of the Raman functional group indexes with exposure time for the PB microstructure of HIPS subjected to thermo-oxidation at 90 °C: (Ml) trans-1,4; (O) cis-1,4; (@) vinyl- 1,2.
Fig. 6. Isocronal representation of the storage modulus E’ (lower plot) and loss modulus E’ (upper plot) for virgin HIPS: (¥) 0.1 Hz; (x) 0.25Hz; (MM) 1Hz; (©) 3.98 Hz; (@) 10 Hz; (8) 39.81 Hz.
Fig. 7. Viscoelastic properties as a function of temperature for selected HIPS samples subjected to multiple processing; (a) storage modulus (£’) and (b) loss modulus (£’): (@) virgin HIPS; (CO) HIPSr1; (©) HIPSr4; (p>) HIPSr6; (Ml) HIPSr9.
Fig. 8. Viscoelastic properties as a function of temperature for selected HIPS samples subjected to thermo-oxidation at 90 °C; (a) storage modulus (£’) and (b) loss modulus (£’’): (@) virgin HIPS, (C4) aged 2 days, (©) aged 4 days, (p>) aged 8 days, (O) aged 12 days, (Ml) aged 16 days.
Fig. 9. Arrhenius maps for the PB and PS glass transition relaxations for selected HIPS samples subjected to multiple processing: (@ virgin HIPS; (4) HIPSr1; (©) HIPSr4; (p>) HIPSr6; (Ml) HIPSr9.
Fig. 10. Arrhenius maps for the PB and PS glass transition relaxations for selected HIPS samples subjected to thermo-oxidation: (@) virgin HIPS, (LC) aged 2 days, (©) aged 4 days, (p>) aged 8 days, (O) aged 12 days, (I) aged 16 days.
Fig. 11. SEM micrographs of HIPS samples: (a) virgin HIPS (low magnification); (b) virgin HIPS (high magnification); (c) reprocessed HIPS (9 cycles); (d) thermo-oxidated HIPS (4 days); (e) thermo-oxidated HIPS (8 days) and (f) thermo-oxidated HIPS (16 days). peratures with increasing exposure time to thermo- oxidation, and is especially noticeable for longer exposure times (Fig. 10). The chemical reactions induced by oxidation are associated with an increase in the glass transition temperature of polybutadiene [8,28], which can be related to the changes in the PB microstructure. On one hand, oxidation causes extensive crosslinking in the PB phase, which restricts the mobility of the polymeric chains. On the other hand, as confirmed by Raman spectros- copy, oxidation affects the cis-1,4 and trans-1,4 con- formers more severely than it does that of vinyl-1,2; this leads to oxidised HIPS samples with higher vinyl content than the original ones, which exhibit higher glass transition temperatures. The free-vol- ume parameter, however, shows a slight decrease This contrasting behaviour for short and long exposure times to thermo-oxidation becomes more evident for the PS phase. The Arrhenius plots for the PS glass transition shift to higher temperatures for shorter exposure times, but drastically shift to lower temperatures for longer times; similarly, the
Scheme 1 - Key parameters for the quality assessment of recycled plastics.
Scheme 2 - Sampling of the different HIPS materials through the mechanical recycling process Polymeric materials suffer degradation processes in each step of their life cycle, mostly in processing and service life, which modify their mechanical properties and long-term stability [2]. An experimental approach entailing multiple pro- cessing and thermo-oxidation has been proposed, to model the degradation processes undergone by recycled polymers during their life cycle [5]. Different strategies can be employed for the characterisation of polymer degradation: analysing the changes in the chemical, physical and mechanical proper- ties; studying the variations in molar mass and composition; or determining the degradation products [6]. An integrated analytical approach considering the macroscopic properties, HIPS samples were collected for analysis at different points of the mechanical recycling process (Acteco, Spain). Scheme 2 shows the mechanical recycling flow diagram and the points at which the different samples were taken: Scrap HIPS employed as raw material in the recycling process, intermediate samples
Fig. 1 - Determination of polymeric impurities in the HIPS samples by DSC: thermograms of the second melting ramp.
Fig. 2- TGA mass-loss thermograms resulting from the thermal decomposition of the HIPS samples.
Fig. 3 - FTIR spectra of the HIPS samples: (a) hydroxyl region (3100-3600 cm~‘); (b) carbonyl region (1620-1800 cm-~*); (c) unsaturated region (880-1000 cm~*).
Fig. 4 -— FTIR functional group indexes (hydroxyl; carbonyl; trans-1,4; vinyl-1,2) for the HIPS samples.
Fig. 5 - Curve fitting of the Raman spectra for the determination of the three individual PB conformers in the 1550-1700 cm-? region: (a) virgin HIPS; (b) HIPS1; (c) HIPS3; (d) HIPS5; (e) HIPS6.
Fig. 6 - Raman functional group indexes (vinyl-1,2; cis-1,4; trans-1,4) for different HIPS samples.
Fig. 7 - Total ion chromatogram (TIC) of the low molecular weight compounds extracted from virgin HIPS.
Figure 2
Figure 3
Figure 2. Schematic drawing of microenvironment chamber for accelerated ageing tests. Wallstrom et al., Microbiological growth testing of polymeric materials: an evaluation of new methods, Polym. Test. 24, 5,557, Copyright Elsevier (2005); Printed with permission.
Figure 3. Procedure for modelling the life cycle of recycled plas- tics: a) multiple processing; b) thermo-oxidation. Vilaplana et al., Degradation of recycled high-impact polystyrene. Simulation by reprocessing and thermo-oxidation, Polym. Degrad. Stab. 91, 9, 2163, Copyright Elsevier (2006); Printed with permission.
Recent research carried out by our group on the char- acterisation of recycled polymers has lead to the identi- fication of three key properties for the quality assessment Figure 4. Key properties for quality assessment of recycled plas- tics. Vilaplana et al., Analytical strategies for the quality assess- ment of recycled high-impact polystyrene: A combination of thermal analysis, vibrational spectroscopy, and chromatography, Anal. Chim. Acta 604, 1, 18, Copyright Elsevier (2007); Printed with permission.
Figure 7. DSC analysis of oxidative stability of reprocessed and recycled HIPS using OIT measurements at 160 °C.
Figure 8. Monitoring the FTIR functional group indexes in waste HIPS samples throughout the mechanical recycling process.
Figure 9. Comparison of the efficiency of brominated flame retardant extraction using different extraction procedures.
the sample materials employed in the analyses. HIPS samples were collected for analysis at different points of the mechanical recycling process (Acteco, Spain). Figure 3.2 shows the mechanical recycling flow diagram and the points at which the different samples were taken: Scrap HIPS employed as raw material in the recycling process, intermediate samples after grinding and washing, and different grades of final recycled HIPS material. Virgin HIPS, commercial grade Polystyrol 486M (BASF Espafila S.A., Spain), was employed as reference material. Table 3.1 describes the sample materials employed in the analyses. Table 3.1 Description of the HIPS materials sampled from the large-scale
Table 3.2 Composition of the standard polymeric samples from waste electrical and electronic 3.2 CHARACTERISATION TECHNIQUES
xidative stability of reprocessed and thermo-oxidated HIPS samples was assessed b ie determination of the oxidation induction time (OIT) and the oxidation temperatur "4): Table 4.1 presents the OIT and the T., average data obtained by the DS(¢ leasurements for the HIPS samples. As it can be observed, the stabilising syster nployed in the material is clearly affected by the reprocessing cycles and by therma xidative degradation, while the largest changes are observed in the aged samples. Eac! processing step caused a progressive consumption of the stabilisers in the materia ainly during the first three extrusion cycles. In the case of the thermo-oxidated samples ie decrease in the stabilising activity is even more fast and dramatic, with a decrease a ie 57% in the value of the OIT after 1 day of exposure at 90°C and a total decrease a 9% of the OIT value after 16 days of ageing. Table 4.1. Oxidation temperature (Tox) and oxidation induction time (OIT) for high-impact polystyrene subjected to multiple processing and thermo-oxidation at 90°C.
reprocessing and thermo-oxidation, respectively. Table 4.2. Influence of multiple processing on the viscoelastic parameters related to the glass transition relaxations of PB and PS phases in HIPS according to the free volume theory
Table 4.3. Influence of thermo-oxidation at 90°C on the viscoelastic parameters related to the properties reported in other works [67, 69, 110]. glass transition relaxations of PB and PS phases in HIPS according to the free volume theory.
Table 4.4. Relative abundance and chromatographic properties of identified low molecular weight compounds in reprocessed HIPS samples.
* Identification by injection of standard substances; > Proposed identification by comparison to the NIST database; ¢ Proposed identification through bibliographic reference [127]; ¢ Proposed identification through bibliographic reference [124]; ¢ Relative quantification respect 4-methylstyrene (LS.); f Relative quantification respect o-terpheny] (LS.) Styrene (peak 1) shows a dramatic reduction in its relative abundance during short time
which indicates that the morphology of the samples seems to be similar. DSC was employed to calculate the glass transition temperature of the PS matrix and to assess the oxidative stability of the different HIPS samples (Table 4.6). In polymeric materials, the glass transition temperature (T’,) is particularly related to the mobility of the polymeric chains and determines the transition between the glassy and the rubbery polymeric state. Variances in the glass transition temperature may be due to several structural effects of the polymers, such as molar mass, degree of crosslinking, chain branching, or physical ageing phenomena [128]. The different samples present comparable T, values between 90 and 95°C for the polystyrene (PS) phase of HIPS, which indicates that the morphology of the samples seems to be similar. Table 4.6. Thermal parameters of differential scanning calorimetry (DSC): Glass transition temperature of the polystyrene phase (T,), oxidation induction time (OIT), and oxidation
Table 4.7. Results from thermogravimetric analysis: Onset temperature of thermal degradation han the virgin material, with HIPS2 and HIPS7 showing the highest residue levels. (Tonset), decomposition temperature range, temperature of maximum decomposition rate (Tmax)
«Proposed identification by comparison to the NIST database; > Proposed identification through bibliography [121]; * Proposed identification through bibliography [124]
The optimisation of the spectrometric detection was achieved by injection of standard solutions of the analytes in tetrahydrofurane in the range 1 — 1000 ug/ml into the HPLC- UV. The initial chromatographic parameters (column, mobile phase, mobile flow, temperature) were first directly chosen from previous bibliographic results [85], and further adjustments were performed to satisfy the requirements for successful se and detection. Different wavelengths for the DAD detection were tested and wavelength of 220 nm was selected. The retention times, limit of detection (LO paration finally a D), limit of quantification (LOQ), and the linearity range for TBBPA and Deca-BDE have been calculated for the developed HPLC-UV method and are presented in Table 4.9. calculated for the developed HPLC-UV method and are presented in Table 4.9. Table 4.9. Limit of detection (LOD), limit of quantification (LOQ) and linearity of the analytical
Che limit of detection (LOD) and limit of quantification (LOQ) for the studied flame etardants were calculated from the reference solutions for each compound and juantification MRM ion pairs (Table 4.10). HBCD has a relatively higher LOD and LOQ compared to TBBPA and Deca-BD! EF, due to the relatively low ionisation efficiency in \PCI. Other studies have pointed out the idoneity of electrospray ionisation (ESI) for he analysis of more polar flame retardants such as TBBPA and HBCD [129-132] olybrominated diphenyl et , but hers generally cannot be analysed using | ESI, which is why \PCI was selected. The linearity range of each analyte is also shown in Table 3.8; the lynamic range of Deca-BD! E, was lower compared to the other compounds. Regardless of these differences, the quantification of the extracts was performed adjusting the ‘oncentration to the linearity range of the flame retardants in the HPLC-MS/MS nethod. In general, the MRM signals obtained from both Br, and Br,, isotopes at the hird quadrupole (Q3), can be used for the determination of the selected BFRs, with imilar LOD, LOQ, and line arity conditions. Table 4.10. Limit of detection (LOD), limit of quantification (LOQ) and linearity of the
Table 4.11. Calculated accumulative concentration of BFRs in the standard HIPS samples usin:
Table 4.12. Calculated accumulative concentration of BFRs in the standard HIPS samples using ultrasound-assisted extraction under different conditions.
Table 4.13. Calculated accumulative concentration of BFRs in the standard HIPS samples usin, the three HBCD congeners. MAE offers almost complete recovery of TBBPA and HBCD using isopropanol/n- hexane as solvents at 130°C for 60 minutes, with calculated concentrations similar to the initial BFR composition of the standard HIPS samples, whereas lower calculated concentrations are obtained for Deca-BDE (Table 4.13). The effect of microwaves and high temperatures may cause isomerisation of the B- and y-HBCD congeners into the more thermally stable a-HBCD, as shown by the anomalous concentration results for the three HBCD conoenets. microwave-assisted extraction under different conditions.
* Parameters calculated from the Fuoss—Kirkwood plot at a frequency of 1 Hz. Influence of thermo-oxidation on the viscoelastic parameters related to the glass transition relaxations of PB and PS phases in HIPS according to the free-volume theory Table 2
* Identification by injection of standard substances; ” Proposed identification by comparison to the NIST database; ° Proposed identification through bibliographic reference [24]; ‘ Proposed identification through bibliographic reference [27]; ° Relative quantification respect 4-methylstyrene (I.S.); ‘ Relative quantification respect o-terpheny] (1.S.)
~ 1aenutication Dy injection Of Standard substances; § rroposed 1aenulicauon Dy CoOMparison to the Niol database; ° Proposed identification through bibliographic reference [24]; * Proposed identification through bibliographic reference [27]; ° Relative quantification respect 4-methylstyrene (I.S.); ' Relative quantification respect o-terpheny] (1.S.)
were carried out in a Mettler-Toledo SDTA/TGA851 (Columbus, OH). Approximately 10 mg of sample was heated from 40°C to 700°C at a heating rate of 10°C min“, under a nitrogen gas flow of 50mLmin-}. after grinding and washing, and different grades of final recy- cled HIPS material. Virgin HIPS, commercial grade Polystyrol 486M (BASF Espanola S.A., Spain), was employed as reference material. Table 1 describes the sample materials employed in the analyses.
Table 2 - Thermal parameters of differential scanning calorimetry: glass transition temperature of the polystyrene phase (Tg), oxidation induction time (OIT), and oxidation temperature (Tox) lene and polypropylene contaminations, respectively, in these materials.
able 3 - Results from thermogravimetric analysis: onset temperature of thermal degradation (Tonset), decomposition >mperature range, temperature of maximum decomposition rate (Tmax), and residue percentage
Liquid Chromatography
Calculated BFR accumulative concentration (mg/g)
Table 1. Continued.
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Qualitative and quantitative analysis of wood samples by Fourier transform infrared spectroscopy and multivariate analysis
by Emilia Bramanti

2010, Carbohydrate Polymers

Fourier transform infrared (FTIR) spectroscopy, in combination with multivariate analysis, enable the analysis of wood samples without time-consuming sample preparation. The aim of our work was to analysis the wood samples qualitatively... more
Fig. 1. The 1900-800 cm—' region of the FTIR spectra of (A) softwood, (B) hardwood and (C) mixture species.
Fig. 2. PCA of the first derivative FTIR spectra of 12 wood samples (1900-800 cm-'): (A) scores scatter of PC1 (91.0%) vs PC2 (5.7%) and (B) loadings profile of PC2. PCA was also performed on the first derivative FTIR spectre (1900-800 cm—!) of 12 wood samples and different detergent fibers (DNSF, ADSF, and SASF) obtained by chemical processing of the same woods (see Section 2). Wood and NDSF differ only for neu- tral detergent soluble fraction. Hemicellulose, cellulose and lignin are intact in NDSF. NDSF and ADSF differ because of hemicellulose content: indeed, ADS solubilizes hemicellulose component. SASF
Fig.4. HCA of FTIR spectra of 12 wood samples (1900-800 cm~'). Spectral data were classified into classes according to their spectral heterogeneity. The first derivation and vector normalization was utilized as pretreatment method of the spectra.
Fig. 3. PCA of the first derivative FTIR spectra (1900-800 cm~! region) of 12 wood samples and NDSF, ADSF and SASF extracted by the Van Soest method: (A) scores scatter of PC1 (71.5%) vs PC2 (14.9%), (B) scores scatter of PC1 (71.5%) vs PC5 (1.5%) and (C) loadings profile of PC2 (bold line) and PC5 (dotted line).
Fig. 6. Scatter plots of analytically determined vs predicted values for content of (A) lignin, (B) cellulose and (C) hemicellulose by PLS.
4 Short rotation coppice. Compositional analysis of biomass based on the Van Soest method. Table 2
Summary of papers concerning wood chemical analysis employing FTIR approach. Table 1 J) (Table 2). The wood samples were ground to a particle size of 200 pm. The wood sampling and preparing procedure is provided in TAPPI T 257 cm (1985).
Assignment of bands in the infrared spectra of wood samples. Table 3 known composition (three-fourths of softwoods and one-fourth of hardwood). and ADSF differ for cellulose component. The scores scatter plot of the first two PCs (Fig. 3A) account for 86.4% of the total vari- ability. As expected, the SASF group, which contains only lignin and insoluble minerals, is separated from the others with positive PC2 scores. Fig. 3B shows the scores plot of PC1 and PC5 which describe 71.5 and 1.5% of the total variability, respectively. PC5 is mainly responsible for the separation of wood samples, NDSF and ADSF, from ADSF showing more negative scores than NDSF and NDSF more negative than wood samples (Fig. 3B). Wood samples and NDSF show a reasonable overlap, but the two groups were still discernable. In the PC2 loadings profile (Fig. 3C), positive values are found for broader signals corresponding to lignin (1595, 1270, and 1160 cm7!) and cellulose (1440, 1135, and 997 cm~'), indicat- ing that lignin and cellulose predominate in SASF group and the other groups, respectively (with positive PC2 scores). PC5 loadings (Fig. 3C) may be used to interpret the separation of ADSF group as their scores are strongly negative in the PC5 axis. Negative load- ings are found at absorption bands characteristic of C=O stretch on conjugated p-substituted aryl ketones (1670cm~') in lignin and C=O and C=C stretching and CH2 rocking (1100 and 1030 cm7~!) in cellulose (Adler, 1977; Dokken, Davis, & Marinkovic, 2005).
Statistical data obtained in connection with calibration of the PLS model. Details are given of the explained variation of the Y matrix RY, the predicted variation of the Y matrix Q2, the correlation coefficient for the observed value as a function of the predicted value R, the root-mean-square error of estimation RMSEE.
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Simultaneous determination of three surfactants and water in shampoo and liquid soap by ATR-FTIR
by Ivano Gutz

2005, Talanta

It is demonstrated for the first time that the principal constituents of a shampoo as well as of a liquid soap -three surfactants and water-can be determined directly, simultaneously and quickly in undiluted samples by attenuated total... more
Fig. 2. Infrared spectra of (a) sodium lauryl ether sulfate 27% (w/w), (b) cocoamidopropy! betaine 30% (w/w), (c) cocodiethanolamide 80% (w/w), (d) alkylpolyglucoside 50% (w/w), (e) water, (f) liquid soap, (g) shampoo and (h) blanked region (2515-1800 cm~!),
Fig. 3. Comparison of absolute errors resulting from the application of the CLS (A) and ILS (@) methods, for the surfactant in lowest concentration in eac formulation, expressed as % of total weight as a function of the actual values. CDEA in shampoo (left) and of APG in liquid soap (right). The normalization of the absorbance values of all spectra by using water as the “internal standard” is a concept ap- plied here to help to compensate minimum changes or fluc- tuations in instrumental and environmental conditions and assure higher accuracy. Table 6 reveals that in most cases deviations are slightly reduced after normalization to unity. For the narrow range of water bracketed here, there is no need to refine the normalization by taking into account the water content found in the first calculation (last column of As it is, the method can be applied directly in the pro- duction process of shampoo and liquid soap, just before the final addition of fragrance. The presence of colorants in such
Table 2
Levels of the surfactants present in the standard samples @ The water concentration was considered the sum of the water content in each added surfactant plus the added water in the formulation. For the CLS quantification method, data at 200 wavenum- bers of the spectrum was used. A comparison was made se- ecting one contiguous region or selecting four blocks of 50 wavenumbers as given in Table 3. The second procedure was found more satisfactory. For the ILS method, data at the 10 wavenumbers given in Table 4 was used. The wavenumbers were carefully chosen looking for the best compromise of high molar absortivity of the minor components (CAPB and CDEA in shampoo and CAPB and APG in liquid soap) and ow relative interference of the other components. A171 a... be Li. '....] £.... lL. Cee] 1° 2) ee ee (TLIC OY Table 3 Table 1
Wavenumber regions selected for the CLS method and corresponding sur. factant(s) with highest absortivity
Absorption regions of the analytes and attributions [32-36] Wavenumber regions selected for the ILS method and corresponding surfac- tant(s) with highest absortivity
Average, lower and higher relative errors (RE) of the values found by FTIR-ATR forthe components in shampoo and liquid soap formulations by both calculatic methods methods. All results are within 0.07% of the expected val- ues, the mean deviations for CDEA being 0.02% by CLS and 0.03% by ILS, and for APG, 0.02% by CLS and 0.02% by ILS. There is also no perceptible change of the random dispersion along the surfactant concentration axis. Table 6), although this may be necessary in samples where the “intemal standard” can vary in a wider range.
\verage relative error results of the different normalization procedures
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Geopolymeric materials prepared using Class F fly ash and elevated temperature curing
by Semesta Alam

2005, Cement and Concrete Research

This paper reports the results of the study of the influence of elevated temperature curing on phase composition, microstructure and strength development in geopolymer materials prepared using Class F fly ash and sodium silicate and... more
Fig. 1. XRD traces of fly ash. Q=quartz, M=mullite, H=hematite.
Fig. 2. Compressive strength development in fly ash activated by sodium hydroxide and cured at 75 °C after 2 h precuring at room temperature (Case 1 75C). Strength of materials was increased in Case II 75C and Case II 95C as compared to Case III 75C due to longer period of elevated temperature treatment (Figs. 3 and 4), 24 vs. 6 h. For both types of activators, materials formed at 95 °C had higher strength than materials formed at 75 °C if 24 h heat treatment was employed. However, this trend was inversed for materials formed with sodium hydroxide when 6 h heat treatment was employed (Case III 95C and Case II 75C). Materials cured at 75 °C (Case III 75C) had higher strength than materials cured at 95 °C (Case III 95C). An
Fig. 4. Compressive strength development in fly ash activated by sodium hydroxide and cured as in Case II 95C, Case II 75C, Case III 95C and Case Ill 75C. The specimens were held at room temperature in tap water after the heat treatment. When stored at room temperature in air, Case II 95C samples prepared with sodium silicate had up to 20% loss of strength, as shown in Fig. 5. These samples were stored covered by hydrophobic film and by thin plastic. Materials
Fig. 3. Compressive strength development in fly ash activated by sodium silicate and cured at 75 °C after 2 h precuring at room temperature (Case I 75C).
Fig. 6. Compressive strength development in fly ash activated by sodium silicate and cured as in Case II 95C, Case II 75C and Case III 95C. The specimens were held at room temperature in tap water after the heat treatment. Figs. 7 and 8 present XRD traces of the samples prepared with sodium silicate and sodium hydroxide solutions, respectively. It was found that the main phases formed in the samples are amorphous, and only in the case of materials prepared with sodium hydroxide solution were semicrystal- line zeolitic phases present after 1 month of storage. The zeolitic products formed depended on the curing regime. In materials with 2 h precuring at room temperature and
Fig. 5. Compressive strength development in fly ash activated by sodium silicate and cured as in Case II 95C, Case II 75C and Case III 95C. The samples were held at room temperature RH=70% after the heat treatment.
Fig. 8. XRD traces of (a) Class F fly ash, and Class F fly ash mixed with sodium hydroxide activator and cured; (b) as in Case III 95C, 1 month; (c) as in Case III 95C, 5 days; (d) as in Case II 75C, 1 month; (e) as in Case II 75C, 1 month; (f) as in Case I 75C, 1 month. Ch=chabazite, P=Na-P1 (gismondine), N=hydroxysodalite, A=Linde Type A, Q=quartz, M=mullite, H=hematite. Fig. 9a and b presents the IR spectra of samples prepared with sodium hydroxide and sodium silicate solutions, respectively. The FTIR spectrum of the alkali-activated fly ash samples shows some differences when compared to the
Fig. 7. XRD traces of (a) Class F fly ash, and Class F fly ash mixed with sodium silicate activator and cured; (b) as in Case III 95C, 1 month; (c) as in Case II 95C, 1 month; (d) as in Case II 75C, 1 month; (e) as in Case I 75C, 1 month. A=poorly crystalline Linde Type A precursor, G=poorly crystalline aluminosilicate gel, Q=quartz, M=mullite, H=hematite.
Fig. 9. FTIR spectra of (a) Class F fly ash mixed with sodium hydroxide activator and (b) Class F fly ash mixed with sodium silicate activator: A=initial material fly ash, and materials cured 1 month, B as in Case III 95C, C as in Case II 75C, D as in Case II 95C.
Fig. 10. SEI of geopolymer materials formed by reaction of Class F fly ash with (a) sodium hydroxide solution, and (b) sodium silicate solution and cured as ir Case II, 95 °C.
Fig. 11. SEI of geopolymer materials formed by reaction of Class F fly ash with (a) sodium hydroxide solution, and (b) sodium silicate solution and cured as i1 Case II, 75 °C. Fig. 1 3a and b shows plots of the (Nat+K+Ca)/Al vs. Si/ Al ratios for the specimens prepared using sodium hydroxid I 95C. inear re e activator, and cured as in Case II 75C and Case There was a linear relationship between the two ratios for the specimen cured as at 95 °C, while no clear ationship was observed in the case of the fly ash activated by sodium hydroxide and cured at 75 °C, where data points fall in a circular area. Fig. 14a—-c presents the plots of t prepared he (Na+K+Ca)/Al vs. Si/AI ratios for the specimens using sodium silicate activator, and cured as in Case 75C, Case II 75C and Case II 95C. For specimens cured at 75 °C, the linear relationships were not well defined. The relationships are consistent with the view that the analyses Some of the microanalyses were of residue of fly ash particles, which were defined as “fly ash”; most were of the materials present in the matrix, which were described as “gel”. The microanalyses confirmed that the major hydration product was aluminosilicate gel in all samples. In addition to Al, Si, amounts of Fe, Na, Ca, K, Mg, P and Cl were found
Fig. 13. Results of X-ray microanalysis plotted in the axis (Na+K+Ca)/Al vs. Si/Al, atomic ratios, for specimens prepared using sodium hydroxide solution, 8% Na, and cured (a) 24 h at room temperature, and 24 h at 75 °C (Case II 75C), and (b) 24 h at room temperature, and 24 h at 95 °C (Case II 95C). are of aluminosilicate gel with variable composition. Table 3 summarises the observations of the Si/Al ratios of the analyses presented in Figs. 13a and b and 14a-c.
Fig. 12. SEI of geopolymer materials formed by reaction of Class F fly ash with (a) sodium hydroxide solution, and (b) sodium silicate solution and cured as in Case III, 95 °C.
Fig. 14. Results of X-ray microanalysis plotted in the axis (Na+K+Ca)/Al vs. Si/Al, atomic ratios, for specimens prepared using sodium silicate solution, 8% Na, and cured (a) 2 h at room temperature and | month at 75 °C (Case 175 °C), (b) 24 h at room temperature, and 24 h at 75 °C (Case II 75C), and (c) 24 h at room temperature, and 24 h at 95 °C (Case II 95C).
Composition of fly ash (mass%) by XRF Table 1
Summary of experimental programme
Summary of X-ray microanalysis Table 3
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Identification of reaction compounds in micrometric layers from gothic paintings using combined SR-XRD and SR-FTIR
by Trinitat Pradell and 
1 more
Nati Salvadó

2009, Talanta

Synchrotron radiation X-ray diffraction (-SR-XRD) and Fourier transform infrared spectroscopy (-SR-FTIR) are used in the non-destructive identification of reaction and aging compounds from micrometric ancient painting layers. The... more
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Further Understanding of the Adsorption Mechanism of N719 Sensitizer on Anatase TiO 2 Films for DSSC Applications Using Vibrational Spectroscopy and Confocal Raman Imaging
by George Demopoulos and 
2 more
Mario A Gomez
Samir Elouatik

2010, Langmuir

Vibrational spectroscopic studies of N719 dye-adsorbed TiO 2 films have been carried out by using SERRS, ATR-FTIR, and confocal Raman imaging. The high wavenumber region (3000-4000 cm -1 ) of dye adsorbed TiO 2 is analyzed via Raman and... more
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Characterization and quantitation of aprepitant drug substance polymorphs by attenuated total reflectance fourier transform infrared spectroscopy
by Robert Wenslow

2003, Analytical Chemistry

In this study, we report the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT-IR) for the identification and quantitation of two polymorphs of Aprepitant, a substance P antagonist for... more
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Interactions between Acidic Crude Oil and Alkali and Their Effects on Enhanced Oil Recovery
by Abhijit Samanta

2011, Energy & Fuels

Alkaline flooding is a method of enhanced oil recovery, in which alkali reacts with acidic components in the crude oil to form surface-active substances. In the present study, the interaction between alkali and crude oil was studied by... more
Figure 1. Schematic of the experimental setup for alkali flooding in sand packs.
Figure 3. Surface tension of the alkali/aqueous phase of crude oil after alkali treatment at different concentrations of NaOH. Figure 2. Schematic flow diagram of alkali flooding.
Figure 5. Schematic diagram of the alkali—petroleum acid interaction. Figure 4. pH of the alkali/aqueous phase of crude oil after alkali treatment at different concentrations of NaOH.
because of the dissociation in the aqueous phase, giving rise to hydroxide ions. This hydroxide ion must react with petroleum acids from the crude oil to form a surfactant. A mechanism is shown in Figure 5. Table 1. Functional Group in the IR Spectra of the Crude Oil
Figure 7. FTIR spectrum of crude oil after the interaction with 1.0% alkali.
Figure 8. FTIR spectrum of the aqueous phase after the interaction of oil with 1.0% alkali.
Figure 9. Production performance of 0.5% NaOH flooding.
Figure 10. Production performance of 0.7% NaOH flooding.
Figure 11. Production performance of 1.0% NaOH flooding.
Figure 12. Production performance of NaOH flooding. above 95%, it Figures 9—11. PEeLIMeADUILy, LUTE Wall MOOI IS, ds UlE Waler CUL Teaches was subsequently flooded with alkali slugs, followed by chase water. The recovery of oil and water cut with PV injected for three different systems is presented in The parameter “A” represents the volume of alkali slug (in PV) injected. It has been found that water begins to break through when the injected volume of water reaches 0.15 PV, and then water cut sharply increases above 90% for each case. During injection of alkali slug, the water cut declines gradually and then reaches 100% at the end of flooding. When alkali is injected, the in situ surfactant is formed along with emulsification of the trapped cure oil in the sand pack, which leads to the formation of an oil bank and consequent drop in the injection rate, and thus, a sudden drop in water cut occurs. To compare the efficiency of three systems, the same volume (0.5 PV) of slugs having differen t concentrations was injected. Figure 12 shows that the cumulative oil recovery by alkaline flooding is higher in the case of a higher concentration of alkali solution because o significant changes in physicochemical and petrophysical proper- ties. The alkali significantly reduces the IFT between oil and water. If the IFT is low enough, residual oil in a water-wet core could be emu results in a red and areal swee water flooding 1.0% alkali slug oil is increased volume of injec sified and move downstream. The mechanism uced water mobility that improves both vertica! p efficiency. The additional recovery of oil over is 13.88, 14.77, and 15.27% when 0.5, 0.7, and was used, respectively. An additional recovery o with an increased concentration of alkali and ted alkali slug. However, the proper design of the alkali slug shou the operating c d be performed by feasibility analysis, considering osts and market value of the crude.
because most of the acidic components of oil react with alkali to form the surfactant, according to eq 1.
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The effects of mechanical and chemical modification of TiO2 nanoparticles on the surface chemistry, structure and fouling performance of PES ultrafiltration membranes
by jaleh mansouri

2011, Journal of Membrane Science

Recently, TiO 2 nanoparticles blended within polymeric membranes have shown to provide improvements in fouling performance. However, agglomeration of nanoparticles remains as one of the major obstacles for generating a uniform surface,... more
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use.
Fig. 1. FTIR spectra of unmodified P25, Chemically modified TiO2 with APTES and Pure APTES: (a) from 2300cm~! to 3550cm~! and (b) from 650cm~! to 1700cm-!. where, Jr is the BSA filtration flux which is set at 50L/m2h in our experiment (TMP was considered after 2 h filtration). Jer and Jar are the pure water flux of membrane before and after fouling, respectively. Fouling behavior can be demonstrated by esti- mation of resistance of membrane as shown below:
Flux recovery and final TMP within 3 cycles of fouling-cleaning experiments for control and 2 wt.% mechanically and chemically modified TiO2 blend membranes.
Fig. 3. A typical TGA for a 2 wt.% unmodified TiO flat sheet blend membrane (10cm x 20cm) TGA and EDAX. The presence of TiO) was investigated by EDAX analysis which confirms the existence of TiO2 on the top surface The results in Table 1 show that the TiO2 average particles size decreased from around 380nm down to below 100nm after mechanical and chemical modifications. To investigate that the chemically modification of TiO2 nanoparticles with APTES has been done successfully, the infrared adsorption of TiO2 nanoparticles was measured. This provides some information about the chemical bonding to the modified TiO, particles. The modification of TiO with APTES is expected to occur by the reaction of surface hydroxyl groups of TiO with the APTES functionalities of silane. The forma- tion of covalent bonds in this reaction can be observed by FTIR. Fig. 1 shows the spectra of unmodified, chemically modified TiO2 with APTES and pure APTES. In the spectral of original unmodified TiOz the sharp band at around 1600 cm! and the broad band at around 3300cm~! are due to absorbed water on TiO2 surface [32-34]. The comparison between the spectral of modified and unmodified TiOz exhibits some new characteristics absorption peaks of APTES, which means the particles were successfully modified by APTES. In the spectra of modified TiO2 with APTES, the bands at around 2926 and 2973 cm—! being to alkyl groups [-(CH),-] [35,36]. Also, the bands at around 1600cm7! are assigned to vibration of pri- mary amine groups and the other vibration amine bands are around 3471 cm! which overlapped with the strong water band at around 3300 cm~![35-37]. In addition to the alkyl and amine groups, the Si-O-C group appeared as a double peak in the spectrum; at around
Fig. 2. Top surface EDS spectra of control and TiO blend membrane (2 wt.%). A. Razmjou et al. / Journal of Membrane Science 378 (2011) 73-84
Fig. 4. The effect of various TiO2 concentrations on the initial weight loss.
Fig. 5. The effect of unmodified and different modified TiO, concentrations on PES membrane structure (300-500).
Fig. 6. The effect of different modified TiO2 concentration on PES membrane structure (1-1.5 K).
Fig. 7. The average contact angles on the top surface of the PES membranes with different modified and unmodified TiO content.
Fig. 9. Control PES membrane prepared from DMAC as solvent by coagulation into mixtures of water and isopropanol (concentration of isopropanol indicated, wt.%) Differential scanning calorimetry (DSC). Glass transition temper- ature (Tg) is very sensitive to chain mobility and may be related to quality of dispersion. The quality of interaction between the nanoparticles and polymer molecules could affect the chain mobil- ity and region of free volume which consequently resulted in reduction or increase in Tg [39,40]. Since the TiOz nanoparticles are highly hydrophilic and PES molecules are hydrophobic, there is a repulsive interaction resulted in a higher chain mobility and region of free volume. Therefore, the T, would be expected to decrease specially after the mechanical modification of particles (Table 3). However, the result for chemical modification shows a significant increase in Tg, which is perhaps due to changing the nature of interaction between inorganic nanoparticles and polymer molecule Fig. 8. Molecular weighs cut-off for modified (mechanically and chemically), unmodified and control membrane.
Average value of glass transition temperature for each type of membrane measured by DSC.
Fig. 10. Absorbed protein by Lowry method for control, unmodified TiO2 and modified (chemically and mechanically) blend membranes (2 wt.%) on the base of nominal surface area.
Fig. 12. Three dimensional AFM images for un/modified blend membrane as well as control membrane. Contact angle. In order to investigate the effect of TiO2 nanoparti- cles on the hydrophilicity or hydrophobicity of the membranes, the angle between a small droplet of water and the flat horizontal sur- face of the membrane was measured by Contact Angle Goniometric Instrument. Results shown in Fig. 7 indicate that the addition of Surface pore size: molecular weight cut-off and cross-section micro- structure. Molecular weight cut-off curves for unmodified and modified TiOz blend membrane as well as control membrane were
Fig. 11. Surface free energy of the membranes calculated by acid-base (van Oss approach.
Fig. 14. Fouling behavior for modified, unmodified and control membrane (0.5 wt.% BSA solution was filtered at constant flux at 5 L/m? h for 2h).
Fig. 13. Effect of modification of TiO2 nanoparticles on the pure water flux of mem- branes.
Effect of modifications on average particle size and polydispersity of TiO2 dispersec in DMAC.
Expected and experimental residual values (wt.%) for different concentrations of TiO2. Table 2 Fig. 4 shows the TGA for control and different blend mem- branes. Higher weight loss below 400°C may be an indication of higher percentage of volatile residues including water, sol- vent, isopropanol and glycerol. Higher absorption may be due to larger pore size or higher porosity. In Fig. 4, the 2 wt.% mechan- ically and chemically modified TiOz loaded membrane lost 74% of its weight which is around 14% greater than the control and 20% greater than the other blend membranes, in average. SEM images (Figs. 5-6) was used to investigate the porosity in the matrix. of the nanocomposite membrane (Fig. 2). A peak observed around 4.5 keV belongs to Ti and the peak around 2.5 keV belongs to sul- fur which comes from PES. To examine if TiO2 is well dispersed in the membrane matrix, thermogravimetric analysis (TGA) test was done on control membrane and different three pieces of a flat sheet membrane with 2wt.% TiO2 (10cm x 20cm). The TGA results were summarised in showing that the residue for all three different samples is 3%. This indicates that the TiO2 nanoparticles were well dispersed throughout the membrane. The casting solu- tion contained 2 g TiOz, 16 g PES and 4g PVP, thus the final amount of TiOz in the membrane should be between 10% and 12.5%, tak- ing into account the fact that part or all of the PVP may leach out during the fabrication process. The decomposition temperature of PES membrane reported between 350°C and 480°C [15,38], with the weight loss between 350°C and 480°C around 25-27%, which includes PES and at least part of the PVP. The ratio of the residual weight (3%) to the organic content of 25-27% yields an estimate of 11-12 wt.% TiO2 in original membrane which is in the expected range. This confirms not only the good dispersion of TiO2 is but also shows that the loss of TiOz2 during fabrication processes was insignificant. However, the ratio of average residual for unmodi- fied TiO2 blend membrane (5%) to 24-29% organic content gives 17-20% which is not in the expected range (10-12.5%), see Fig. 3. This suggests inhomogeneity of membrane in regard to TiO? disper- sion. The same sets of experiments were done for 4 wt.% and 6 wt.% TiO loaded membrane (see Table 2). The results indicate that the modification of particles could provide a good dispersion of TiO in membranes regardless of its concentration. However, there are some differences in the weight loss prior to polymer degradation.
Filtration resistances of control and unmodified TiO2-blend membranes (the experiment repeated three times and the average was reported). Table 4
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Slow pyrolysis of pistachio shell
by Esin Apaydin Varol

2007, Fuel

In this study, pistachio shell is taken as the biomass sample to investigate the effects of pyrolysis temperature on the product yields and composition when slow pyrolysis is applied in a fixed-bed reactor at atmospheric pressure to the... more
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Fractional separation and physico-chemical analysis of lignins from the black liquor of oil palm trunk fibre pulping
by john tomkinson

2001, Separation and Purification Technology

A continuing study of the lignin fractions, separated by a two step precipitation method instead of the traditional one step precipitation method from the black liquor of oil palm trunk fibre pulping (OPTFP), was carried out. The degraded... more
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Methods for lipase detection and assay: a critical review
by Ali Tiss

2000, European Journal of Lipid Science and Technology

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Preparation, Solid-State Characterization, and Surface Chemistry of High Surface Area NixAl2-2xO3-2x Mixed Oxides
by Guido Busca

1992, Chemistry of Materials

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Adsorption properties of HKUST-1 toward hydrogen and other small molecules monitored by IR
by Elena Groppo

2007, Physical Chemistry Chemical Physics

E r l a n g e n -Nü r n b e r g ) , a n d Ad r i a n o Z e c c h i n a ( Un i v e r s i t y o f T o r i n o ) , a n d p u b l i s h e d i n s e l e c t e d 2 0 0 7 p r i n t i s s u e s o f P CCP , a l l p a p e r s a r e c o l l e c t e... more
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Byzantine wall paintings from Mani (Greece): microanalytical investigation of pigments and plasters
by Dionysis Mourelatos

2009, Analytical and Bioanalytical Chemistry

The present case study concerns the technology of Byzantine wall paintings from the Mani Peninsula, Greece. An assemblage of 12 Byzantine churches, constructed in the tenth to fifteenth century, was included in an initial analytical... more
The initial samples were studied under the stereo- microscope in order to describe their surface structure and colour impression. Furthermore, the polished sections were examined under the polarising microscope. This examina-
Ochre The majority of the collected samples presented colours in a spectrum from yellowish brown to orange red.
Fig. 3 SEM micrograph in back-scattered mode of a cinnabar layer in Sample CH02_S2
Blue pigments The FTIR analysis of the blue sample from the Church Aghios Philippos (Fig. 5: CH10_S2) presented a spectrum of low degree of resolution for blue chromo- phores. However, this is something already emerged in FTIR analysis of blue pigments [14]. The evaluation of the spectrum revealed the presence of four peaks at 924, ,030, 1,085 and 1,153 cm !, which are indicative for the presence of lapis lazuli [15]. Moreover, the presence of a weak peak at 540 cm ', which increases its intensity in the first derivative plot, is also characteristic for the stretching vibration of the S-S bond and therefore the presence of ultramarine [14, 16]. The ability of FTIR to identify sulphate compounds is of great importance for wall paintings surveys and highlights the complimentary character of IR with other portable spectroscopic techniques, such as LIBS and EDXRF, since they appear limitations for the identifica- tion of sulphur and light elements in air atmosphere.
Fig. 5 Representative infrared spectra of different inorganic pigment samples from the wall paintings of Mani
Fig. 6 Diffraction patterns of the binding medium from different wall paintings, along with these of the external crust formations (JM illite montmorillonite, Cc calcite, Q quartz, G gypsum and HM hydromagnesite)
layers were analysed by Fourier-transformed infrared spec- troscopy (FTIR). The FTIR analysis was performed in a Bruker, Equinox 55/S spectrometer. Transmittance spectra were collected in the region of 4,000 to 400 cm’, with 4 cm | resolution. The samples were mixed with KBr and scanned 40 times, in order to reduce the signal to noise ratio. tion was mainly focussed on the stratigraphy and thickness of paint layers and preparatory layers. Another aspect was the microstructure of plaster and paint layers, in terms of characteristics such as coherence, inclusions, porosity or size of pigments.
Table 2. Summary of the analytical results: The groups in the last column correspond to the plaster types described in the text
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Detection of Hazelnut Oil Adulteration Using FT-IR Spectroscopy
by Banu Ozen

2002, Journal of Agricultural and Food Chemistry

Figure 1. FT-IR spectra of hazelnut and other oils (canola, soybean, corn, sunflower, walnut, and peanut). The 1400-4387 and 1133-876 cm regions were used for DA and PLS analysis.
Figure 2. Cooman plot for the classification of (a) hazelnut and other oils, and (b) hazelnut oil and sunflower-oil-adulterated hazelnut oil (vertical and horizontal lines show 95% confidence interval).
Figure 3. (a) Calibration curve for sunflower-oil-adulterated hazelnut oil, and (b) cross-validation of the PLS model.
Figure 5. Cooman plot for the classification of (a) extra-virgin olive oil and hazelnut oil, and (b) extra-virgin olive oil and hazelnut-oil-adulterated olive oil (vertical and horizontal lines show 95% confidence interval). Figure 4. FT-IR spectra of hazelnut and extra-virgin olive oils.
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Synthesis, characterization and swelling behaviour of poly(methacrylic acid) brushes synthesized using atom transfer radical polymerization
by Jonathan Howse

2009, Polymer

Poly(methacrylic acid) brushes have been prepared utilizing the “grafting from” technique and a living radical synthesis route using a two stage process. Firstly a poly(1-ethoxyethyl methacrylate) brush was synthesized by atom transfer... more
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Microencapsulated n-octacosane as phase change material for thermal energy storage
by ali karaipekli

2009, Solar Energy

This study deals with preparation and characterization of polymethylmetracrylate (PMMA) microcapsules containing n-octacosane as phase change material for thermal energy storage. The surface morphology, particle size and particle size... more
Fig. 1. SEM image of PMMA/octacosane microcapsules. Surface morphology of obtained microcapsules was studied by a scanning electron microscope (SEM). Fig. 1 shows the SEM particle profiles of PMMA/octacosane microcapsules. Particle size and shape can dramatically alter the physical properties of a substance. The solubility, stability, chemical reactivity, opacity, flowability, and material strength of the materials are affected by the size and characteristics of the microcapsules. The PMMA/octa- cosane microcapsules have spherical shape with a fairly uniform structure and compact surfaces. The particles are smooth without edges or sharp dents. The similar appear- ance was coincided in different microcapsules prepared by using different core and shell material (Fan et al., 2005; Sarier and Onder, 2007; Su et al., 2005). PSD in Fig. 2 rep-
Fig. 2. Particle size distribution of PMMA/octacosane microcapsules. DSC curves of n-octacosane and PMMA/octacosane microcapsules were shown in Figs. 4 and 5, respectively. Thermal properties evaluated from the curves indicate that PMMA/octacosane microcapsules melt at 50.6 °C, freezes at 53.2 °C when pure octacosane has a melting point of
Fig. 4. DSC thermogram of n-octacosane. Fig. 3. FT-IR spectra for octacosane, PMMA and PMMA/octacosane microcapsules.
Fig. 5. DSC thermogram for PMMA/octacosane microcapsules.
The chemical stability of PMMA/octacosane microcap- sules after repeated thermal cycling was also investigated by FT-IR analysis as shown in Fig. 9. The peak positions Fig. 6. TGA analysis of n-octacosane.
Fig. 8. DSC thermogram for PMMA/octacosane microcapsules after thermal cycling. Fig. 7. TGA analysis of PMMA/octacosane microcapsules.
Fig. 9. FT-IR Spectra for PMMA/octacosane microcapsules before and after thermal cycling.
TGA data for PMMA/octacosane microcapsules.
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Extraction and characterisation of pepsin-solubilised collagen from the skin of unicorn leatherjacket ( Aluterus monocerous)
by Ahmad Mehraj

2010, Food Chemistry

Pepsin-solubilised collagen (PSC) was extracted from the skin of unicorn leatherjacket (Aluterus monocerous), using 0.5 M acetic acid in the presence of pepsin from albacore tuna, yellowfin tuna or porcine pepsin at a level of 20 units/g... more
Fig. 1. SDS-PAGE pattern of pepsin-solubilised collagen from the skin of unicorn leatherjacket under reducing and non-reducing conditions. M: high molecular weight markers, I: Type I calf skin collagen, ASC: acid-solubilised collagen, A: pepsin-solubilised collagen using albacore tuna pepsin, Y: pepsin-solubilised collagen using yellowfin tuna pepsin and P: pepsin-solubilised collagen using porcine pepsin. Protein patterns of PSC from the skin of unicorn leatherjacket determined under reducing and non-reducing conditions are illus- trated in Fig. 1. All PSCs consisted of two o-chains and one o- chain. High molecular weight components, including B-, y-compo- nents as well as the cross-linked constituents were also observed in all PSCs. PSCs isolated from the skin of unicorn leatherjacket were most likely classified as Type I collagen, which consisted of a heterotrimer of two identical o,-chains and one o-chain (Muyonga et al., 2004). A slight difference in the protein pattern was noticeable in YPSC, compared with APSC and PPSC. Slight deg- radation of major proteins with the concomitant formation of low molecular weight peptides was noticeable when pepsin from yel- lowfin tuna stomach was used. It was suggested that pepsin from yellowfin tuna stomach was able to hydrolyse tropocollagen, as indicated by the decreased band intensity of B- and o-chains. It was noted that molecular weights of o-chains of all collagens were slightly lower than that of ASC. The results are in accordance with Nalinanon et al. (2007a) who reported that molecular weights of a- chains of collagen from bigeye snapper skin extracted with the aid of pepsin from the same fish species decreased slightly when com- pared with ASC. Hence, it can be inferred that pepsin most likely cleaved some peptides in the telopeptide region. As a consequence, a slight decrease in molecular weight of PSC was noticeable, in comparison with that of ASC. Generally, the higher molecular weight components including y-chain were found at a lower con- tent in PSC, compared with those of ASC. This result indicated that pepsin used in this study could cleave inter-molecular cross-links
Fig. 2. Peptide maps of pepsin-solubilised collagens from the skin of unicorn leatherjacket digested by V8 protease and lysyl endopeptidase. M: high molecular weight markers, A: pepsin-solubilised collagen using albacore tuna pepsin, Y: pepsin-solubilised collagen using yellowfin pepsin and P: pepsin-solubilised collagen using porcine pepsin. The differences in peptide maps between the different PSCs generated by lysyl endopeptidase or V8 protease digestion sug- gested that there might be some differences in their primary struc- tures, especially the o-helix strand, in terms of sequence as well as amino acid composition (Jongjareonrak et al., 2005). Thus the de- gree of hydrolysis by protease might be different, due to variation
Fig. 3. DSC thermogram of pepsin-solubilised collagen from the skin of unicorn leatherjacket dispersed in 0.05 M acetic acid (a) and in deionised water (b). APSC: pepsin-solubilised collagen using albacore tuna pepsin, YPSC: pepsin-solubilised collagen using yellowfin pepsin and PPSC: pepsin-solubilised collagen using porcine pepsin.
Fig. 4. Fourier-transform infrared spectra of pepsin-solubilised collagen from the skin of unicorn leatherjacket. APSC: pepsin-solubilised collagen using albacore tuna pepsin, YPSC: pepsin-solubilised collagen using yellowfin pepsin and PPSC: pepsin- solubilised collagen using porcine pepsin. FTIR spectra of PSCs from the skin of unicorn leatherjacket are depicted in Fig. 4. The absorption bands in the spectra of all PSC samples were situated in the amide band region such as amide | (1600-1700 cm~'), amide II (1500-1600cm7!) and amide III (1200-1300 cm~') as previously reported by Muyonga et al. (2004). For the spectrum of APSC, the characteristic absorption bands at wave numbers of 3293.06, 3079.61, 1631.76, 1546.71 and 1235.36cm7! were observed, whereas YPSC showed main absorption bands at wave numbers of 3294.37, 3079.74, 1639.71,
Fig. 5. Relative viscosity of the solution of pepsin-solubilised collagen from the skin of unicorn leatherjacket at different temperatures. APSC: pepsin-solubilised colla- gen using albacore tuna pepsin, YPSC: pepsin-solubilised collagen using yellowfin pepsin and PPSC: pepsin-solubilised collagen using porcine pepsin. Relative viscosities of PSCs in 0.1 M acetic acid subjected to heat-treatment at different temperatures are depicted in Fig. 5. Collagen solutions are highly structured systems associated with the high viscosity. The collagen is irreversibly destroyed as a result of thermal denaturation. Viscosity of APSC and YPSC decreased continuously when heated up to 32 °C. Rate of decrease was re- tarded in the temperature range of 36-52 °C. The relative decrease of viscosity up to 32 °C might be due to continuous disruption of hydrogen bonds, which stabilised the structure of collagen. Never- theless, PPSC had the marked decrease at temperature above 32 °C.
Fig. 6. Relative solubility (%) of pepsin-solubilised collagen from the skin of unicorn leatherjacket as affected by different pH (a) and NaCl (b) concentrations. APSC: pepsin-solubilised collagen using albacore tuna pepsin, YPSC: pepsin-solubilised collagen using yellowfin pepsin and PPSC: pepsin-solubilised collagen using porcine pepsin. 4. Conclusion Fig. 6 shows the effect of pH and NaCl on the solubility of PSC from the skin of unicorn leatherjacket. All PSCs were solubilised in the pH range of 1-6, with the highest solubility at pH 2 (p < 0.05). The decrease in solubility was observed in the pH range of 7-8 (p < 0.05). The dissolved protein was found to precipitate in this pH range. The observation of precipitation and aggregation at a particular pH can be attributed to hydrophobic interaction among
Amino acid composition of the pepsin-solubilised collagen from the skin of unicorn leatherjacket (expressed as residues/1000 residues). APSC: pepsin solubilised collagen using albacore tuna pepsin, YPSC: pepsin solu- bilised collagen using yellowfin pepsin and PPSC: pepsin solubilised collagen using porcine pepsin. Table 1
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Vibrational spectroscopy of seaweed galactans
by Betty Matsuhiro

1996, Hydrobiologia

Information from classical infrared spectroscopy studies has been of significance for characterizing seaweed galactans . The development of Fourier transform infrared spectroscopy and of Fourier transform laser Raman spectroscopy has... more
Figure 1. FT-IR spectra in the region 4000-400 cm7! of A: agarose and B: methy! 3,6-anhydro-a-methyl-D-galactopyranoside. FT-Raman spectra in the region 3500-10 cm~! of C: agarose and D: methyl] 3,6-anhydro-a-D-galactopyranoside.
Figure 2. FT-Raman spectra in the region 3500-50 cm! of A: «-Catrageenan, B: e-carrageenan, C: A-carrageenan and D: polysac- charide from tetrasporic Iridaea obovata. five bands. According to the literature (Table 2), the signal at 986.9 cm7! is assigned to the vibrational mode of a-glycosidic links coupled to CC and CO vibrations. The spectrum presents a signal at 892.7
Figure 3. FT-IR spectra in the region 4000-400 cm~ ! of A: agar from Gracilaria chilensis, B: polysaccharide from cystocarpic Iridaea obovata. Second-derivative FT-IR spectra in the region 2000-400 cm7! of C: agar from Gracilaria chilensis, D: polysaccharide from cystocarpic [ridaea obovata.
Figure 4, Second-derivative FT-IR spectra in the region 2000— 400 cm~! of A: methyl 3,6-anhydro-a-D-galactopyranoside, B: D-galactose 4-sulfate, C: agar from tetrasporic Gelidium rex and D: polysaccharide from tetrasporic Iridaea obovata.
Figure 5. Second-derivative FT-IR spectra in the region 2000-400 cm! of algal samples. A: Gelidium chilense, B: Gracilaria chilen- sis, C: tetrasporic Chondrus crispus and D: tetrasporic Iridaea obo- vata.
Table 1. Characteristic frequencies in the infrared spectra of sea- weed galactans.
Table 2. Frequencies of interest in seaweed galactans. butions of CC and CO modes (Table 2) is observed at 965.5 cm—!,
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Synthesis, spectral characterization, in-vitro microbiological evaluation and cytotoxic activities of novel macrocyclic bis hydrazone
by Vinod Nagaraju

2009, European Journal of Medicinal Chemistry

A macrocyclic hydrazone Schiff base was synthesized by reacting 1,4-dicarbonyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol and a series of metal complexes with this new Schiff base were synthesized by reaction with Co(II), Ni(II)... more
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XPS investigation of Nafion ® membrane degradation
by Galit Levitin

2007, Journal of Power Sources

After treatment in different Fenton's reagents, chemical changes in Nafion ® membranes were analyzed by X-ray photoelectron spectroscopy (XPS) and clear evidence of polymer degradation was observed. Exposure of the membrane to 2 h of... more
Fig. 1. Effect of Fe* concentration on membrane degradation. Fig. 2 shows membrane degradation rates at different temper- atures for the Fenton’s test. Clearly, degradation rates increase with temperature; FER increased by approximately a factor of 2 after a temperature increase of 10°C. These results suggest that the lifetime of Nafion® membranes will be greatly diminished when operating above 100°C. Therefore, identifying the mem- brane degradation mechanism is crucial to the improvement of membrane durability and can serve as a guide to the development of novel high temperature membranes.
Fig. 2. Degradation rates under different temperatures (Fe?* fixed at 30 ppm).
Fig. 3. XPS spectra changes with X-ray exposure time. Pretreated Nafion® membrane samples were exposed to X- ray radiation in the XPS chamber and XPS spectra were recorded (Fig. 3) as a function of exposure time. X-ray radiation did not cause a discernable change in the chemical structure of the membrane, even after 2h of exposure. Since the typical XPS analysis time for these membranes is only ~20 min, these results demonstrate that there is a sufficient time window to allow Fig. 4(b) shows the O Is spectrum for different membrane samples. Oxygen in Nafion® membranes has two different
Fig. 4. XPS spectra of different membrane samples.
Fig. 5. FTIR spectra of initial, pretreated and tested membrane samples: a (. ) initial membrane sample, b (- - - - - ) pretreated membrane sample, c(- +--+ +++ ++ ++) 300 ppm Fe** treated membrane sample, d (- - - -) 3 ppm Fe** treated membrane sample.
Fig. 6. FTIR spectra of membrane samples in 1900cm~! and 1500cm7! short range: a ( ) initial membrane sample, b (- - - -) pretreated membrane sample, c (-+++++++++++) 300 ppm Fe** treated membrane sample, d (----) 3 ppm Fe** treated membrane sample.
Fig. 7. XPS spectra of fresh and degraded MEAs.
XPS results for different samples in Fenton’s test (H2O2 concentration is fixed at 10 wt.%) Table | tions. At low Fe** concentrations, the main degradation product would be fluoride ion and a very small number of polymer fragments in this mild environment. As the Fe?* concentra- tion increases, t he radicals may attack less active bonds such as C—O in the polymer. For example, Healy et al. [13] found a degradation product in a Fenton’s test bath water with the struc- ture HOOC-—CEF(CF3 )—O-—CF2—-CF2-S0O3H. Therefore, polymer fragments may have been a dominant degradation product, but are not detectab e by ion chromatography. Although the XPS spectra discussed below show a large loss of fluorine from the membrane after tion, the low F— Fenton’s test with the highest Fe?* concentra- emission rate cannot account for this large loss. Nevertheless, Fenton’s test under aggressive conditions may provide sufficient degradation products for further study by NMR and mass spectroscopy; these studies are underway in our laboratory.
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Byzantine wall paintings from Mani (Greece): microanalytical investigation of pigments and plasters
by Ioannis Karatasios and 
1 more
Anno Hein

2009, Analytical and Bioanalytical …

The present case study concerns the technology of Byzantine wall paintings from the Mani Peninsula, Greece. An assemblage of 12 Byzantine churches, constructed in the tenth to fifteenth century, was included in an initial analytical... more
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Vis/NIR estimation at harvest of pre- and post-storage quality indices for ‘Royal Gala’ apple
by Andrew McGlone and 
1 more
Paul Martinsen

2002, Postharvest Biology and Technology

Visible/Near Infrared (Vis/NIR) spectrometric measurements, made with a fast low cost polychromatic spectrometer operating over the range 500-1100 nm, have been made on 'Royal Gala' apples (Malus domestica Borkh.). The spectral... more
The abbreviations for the quality indices are as described in Table 1. QS linearised for regression by taking positive square root—se text. Modelling and regression statistics for Vis/NIR models generated on the harvest and quantitative data sets Table 2
The abbreviations for the quality indices are as described in Table 1. Summary statistics for the fruit quality measurements in the storage data set Table 3
Fig. 1. The Vis/NIR measurement system (not to scale).
Fig. 2. Typical absorbance spectra for ‘Royal Gala’ apples from early harvest (A), mid-harvest (B) and late harvest (C). The prediction models were significant in re- gression terms for all quality indices (Table 2; R’s between 0.63 and 0.78) but poor in prediction terms (Tab e 2; SDRs <2.5). This is clearly ob- served in that the regression graphs show a large amount of scatter in the predicted values (e.g. Fig. 3, SPI). T here is good agreement between the
Fig. 3. Vis/NIR predictions of harvest-time SPI. Summary statistics for QS and TA are reported in Table 1. The raw QS measurements were dis- tributed non-normally, bunching towards value zero, and so to enable linear regression analysis they were transformed by taking positive square roots. The harvest date correlations with QS and TA were very poor (r* = 0.23, 0.14, respectively) and, again, whilst the prediction models were significant for each of the QS and TA indices
Fig. 4. Vis/NIR predictions of post-storage SSC. The fact that post-storage RMSEP results for SSC prediction are consistent with those reported from scanning monochromator instruments im- plies that the performance of non-scanning poly- chromatic systems is not a limiting factor for accuracy. This has also being confirmed in recent measurements on the ‘Pacific Rose’ and ‘Brae-
BC is background colour (scores range 0-10), SPI is starch pattern index (scores range from 0 to 6), SSC is soluble solids content, QS is quantitative starch and TA is titratable acidity. Summary statistics for the harvest time measurements in the harvest and quantitative data sets Table 1
The abbreviations for the quality indices are as described in Table 1. Regression statistics for Vis/NIR models generated on the storage data set
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Variations in Atomic Disorder in Biogenic Carbonate Hydroxyapatite Using the Infrared Spectrum Grinding Curve Method
by Yotam Asscher

2011, Advanced Functional …

Figure 1. Plot of the same enamel sample (human molar tooth 3, i.e., M3, from 23 yr old male) ground to different extents. |) Sample that was least intensively ground. Il) Sample that was most intensively ground. FWHM: full width at half maximum. The IRSF values range from 3.6 to 4.2.
Figure 3. Enamel grinding curves of molar teeth 1 (M1) obtained from 4 individual cows, in solid points, and enamel grinding curves of mola teeth 3 (M3) obtained from 4 human individuals at different ages: 16 yrs, 18 yrs, 23 yrs, and 25 yrs, in hollow points. peak shapes, and the effect of changes in atomic disorder of the material itself. This is possible because the same sample is analyzed after each repeated grinding, which reduces the overall distribution of particle sizes. It is not neces- sary to measure the particle sizes. Thus the trend line of the grinding curve reflects the particle size effect, and the loca. tion of the trend line in a plot of FWHM of the 1035 cm! vs the IRSF reflects atomic disorder effects. Furthermore, by plotting the ratios of two peaks (the 605 and 567 cm”) against the broadening of a third peak (1035 cm”}), we are sam. pling the crystal lattice in 3 different ways. As each absorption has its own coefficient, this provides an effective means of char- acterizing the overall state of order/disorder of the atoms in the
Figure 2. Grinding curves of molar tooth enamel, dentine, mandible bone and cementum from human, horse, cow and dog.
Figure 5. Plot of carbonate content measured by TGA versus the FTIR (n.a.u.: normalized arbitrary units). The linear correspondance in carbonate contents between the two methods has a correlation coefficient of R* = 0.88. Error bars are the standard deviation of triplicate TGA measurements for the same powder. It has been reported that the IRSF values for modern bone samples irrespective of their origin are 2.7 + 0.2,29 but no consistent IRSF differences between bones from different sources have been observed. We note that modern horse bone and cementum lie on different trend lines than modern dog bone and dentine (Figure 2). This may therefore be an indication that there are consistent differences in atomic disorder/crystal size between these members of the bone
Figure 4. a) Enamel grinding curves of different teeth obtained from one cow mandible. M: molar, P: premolar, |: incisor. b) Enamel grinding curves of different teeth obtained from one sheep individual mandible. M: molar, P: premolar. The error bars for each point refer to the free variable error bar calculated from each fit.
Figure 6. a) Carbonate grinding curves of molar tooth enamel from different taxa (n.a.u.- normalized arbitrary units). b) Crystallinity grinding curves of enamel from different taxa. 5. Conclusions
Table 1. Least-square fit parameters for the grinding curves of enamel, bone and dentine.
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Isolation of Anacardic Acid from Natural Cashew Nut Shell Liquid (CNSL) Using Supercritical Carbon Dioxide
by Lupituko Mkayula and 
1 more
Joseph Buchweishaija

2008, Journal of Agricultural and Food Chemistry

Solvent extracted cashew nut shell liquid (CNSL), conventionally known as natural CNSL, is a mixture of several alkenyl phenols. One of these alkenyl phenols is anacardic acid, which is present at the highest concentration. In view of... more
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Thermoregulating response of cotton fabric containing microencapsulated phase change materials
by salaün fabien

2010, Thermochimica Acta

The purpose of this work is to manufacture a thermoregulating textile fabric based on the incorporation of melamine-formaldehyde microcapsules containing a n-alkane mixture. A series of fabrics containing different mass ratios of... more
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Synthesis, Characterization, and Swelling Behavior of Alginate-G-Poly (Sodium Acrylate)/Kaolin Superabsorbent Hydrogel Composites
by ALI Pourjavadi

2007, Journal of Applied …

A novel composite hydrogel was prepared via UV irradiation copolymerization of acrylic acid and maize bran (MB) in the presence of composite initiator (2,2-dimethoxy-2-phenylacetophenone and ammonium persulfate) and cross-linker... more
Figure 1. Proposed reaction mechanism for the synthesis of MB— PAA.
Figure 2. SEM micrographs of (a) MB, (b) PAA, and (c) MB—PAA; (d) FTIR spectra of MB, PAA, and MB—PAA; (e) TG curves of MB, PAA, and MB-PAA; (f) DTG curves of MB, PAA, and MB—PAA.
figure 3. (a) Water-retaining capacity of MB—PAA centrifuged at 6000 rpm and dried at 60 °C; effect of (b) maize bran content on AA and (c) eaction time on water absorbency; water absorbency of superabsorbent hydrogel in (d) KCI, NaCl, NH,Cl, CaCl, MgCl, FeCl, and AICI, and (e) NaCl, Na,SO,, and Na;PO, aqueous solutions; (f) salt sensitivity factor of various salts at a concentration of 150 mmol L™.
Figure 4. (a) Swelling behavior of different hydrogel particle sizes in distilled water absorbency; (b) pseudo-first-order kinetic model; (c) pseudo- second-order kinetic model; (d) water diffusion behavior for different hydrogel particle sizes.
Table 1. Elemental Analysis of MB, PAA, and MB—PAA
Table 2. Effect of Salt Solutions on Water Absorption
The other two (60 mesh and 20 mesh) had similar swelling processes. Table 3. Kinetic Parameters for the Water Absorbency of MB—PAA in Distilled Water larger than that to monovalent anions at the same concentration.
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Binding of organic pollutants to humic and fulvic acids: Influence of pH and the structure of humic material
by Fabrizio De Paolis

1997, Chemosphere

In order to compare their binding capacities, humic acids (HA) and fulvic acid8 (FA) were isolated from water and extracted from sediments, and used to measure partition coefficients (163 for the model compounds benxo(a)pyrene f&P) and... more
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FT-IR Studies on Light Olefin Skeletal Isomerization Catalysis☆III. Surface Acidity and Activity of Amorphous and Crystalline Catalysts Belonging to the SiO2–Al2O3System
by Guido Busca

1998, Journal of Catalysis

The surface acidity of both amorphous and crystalline materials belonging to the SiO 2 -Al 2 O 3 system (i.e., amorphous silicas, amorphous silica-aluminas with different Al contents, HZSM5 and H-ferrierite (FER) zeolites, and silicated... more
T des = Temperature for the desorption upon outgassing; H = hydrogen bonding; P = protonation. Summary of the Data on the Catalysts Bronsted A cidity
FIG. 1. Selectivity vs conversion for FER (a) and silicated alumina ‘b) catalysts.
are shown. The spectra of pure silica samples (Fig. 2g) are just coincident, showing a single sharp band at 3745 cm~!, in agreement with a number of previous data, as reviewed some years ago (30, 31). This band is certainly dominated by the absorption due to the O-H stretching mode of a sin- gle terminal Si-OH group (Scheme 1, Species I), although it is agreed today that it also contains the O-H stretchings
FIG.2. FT-IR spectra of the catalysts HZSM5 (a), FER1 (b), FER2 (c), AS (d), SA 13 (e), SA8 (f), S2 (g) in the O-H stretching region after outgassing at 873K.
FIG.3. FT-IR spectra (4000-2100 cm!) of the catalysts HZSM5 (a), FER1(b),A S(c), SA 13(d), SA 8(e), $2 (f) at 300K in contact with acetonitrile vapour (10 Torr).
FIG. 4. FT-IR spectra (4000-2100 cm~!) of the catalysts HZSM5 (a), FER1 (b), AS (c), SA 13 (d), SA 8 (e), S2 (f) after acetonitrile adsorption at 300 K and successive outgassing at 300 K.
FIG.5. Subtraction FT-IR spectra relative to adsorption of AN onA S:(a) upon contact with A N vapor (10 Torr) with the spectrum of the activate catalyst subtracted; (b) upon contact with A N vapor (10 Torr) and the spectrum of the outgassed catalyst subtracted; and (c) after outgassing at roon temperature with the spectrum of the activated catalyst subtracted.
FIG.6. FT-IR spectra in the C=N stretching region of the adsorbed species arising from acetonitrile adsorption on the catalysts HZSM5 (a), FER1 (b), SA 13 (c), AS (d), and S (e); for each catalyst, the upper spectra are recorded at 300 K in contact with the gas, the lower after further outgassing at 300 K.
FIG. 7. FT-IR spectra of the surface species arising from adsorption of pyridine on a silica-alumina cracking catalyst (13% A 1,03, from Strem) at r.t. (a) and after outgassing at 373 K (b).
FIG. 8. FT-IR spectra of the surface hydroxy groups of a silica-alumina cracking catalyst (13% A1,03, from Strem) after activation at 623 K (a), after contact with pyridine vapor and outgassing at r.t. (b), and after outgassing at 373 K (c).
FIG.9. FT-IR spectra of the adsorbed species arising from contact of FER1 (a) and HZSM5 (b) with Py vapor (3 Torr) and successive outgassing it 473 K.
FIG.10. FT-IR spectra of the surface hydroxy groups of FER1 after activation (a) and after contact with pyridine and successive outgassing at 373 K (b) and 473 K(c). (d) is the subtraction (c - a) showing the perturbation arising from pyridine adsorbed species still existing at 473 K.
SCHEME 3. Reaction network for 2-butene skeletal isomerization based on the main product.
* LHSV = liquid hourly space velocity (liquid feed density = 0.6 g/ml). » Piot= 1 atm; dilution with isobutane. “t; and tz are the times on stream of starting and stopping product collection, respectively. 4 A} aromatics, but maily C8 aromatics. ° Nonaromatic hydrocarbons. n-Butene C onversion Data on Various Catalysts Belonging to the Si02- Al203 System
Characteristics of the Catalysts under Study The HZSM5 sample was from Engelhard (Si/A1 atomic ratio = 23).
Summary of the Data on the Catalysts Lewis A cidity
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Carbon nanotube/polyaniline composite as anode material for microbial fuel cells
by Yan Qiao

2007, Journal of Power Sources

A carbon nanotube (CNT)/polyaniline (PANI) composite is evaluated as an anode material for high-power microbial fuel cells (MFCs). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) are employed to... more
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Adsorption of organic matter at mineral/water interfaces: I. ATR-FTIR spectroscopic and quantum chemical study of oxalate adsorbed at boehmite/water and corundum/water interfaces
by Charles Musgrave

2004, Geochimica Et Cosmochimica Acta

The types and structures of adsorption complexes formed by oxalate at boehmite (␥-AlOOH)/ water and corundum (␣-Al 2 O 3 )/water interfaces were determined using in situ attenuated total reflectance fourier transform infrared (ATR-FTIR)... more
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Study of sulfur poisoning on Pd/Al2O3 and Pd/CeO2/Al2O3 methane combustion catalysts
by Guido Busca

2010, Catalysis Today

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Lignin from Sugar Cane Bagasse:  Extraction, Fabrication of Nanostructured Films, and Application
by Aldo Job and 
1 more
P. A Antunes

2007, Langmuir

Four lignin samples were extracted from sugar cane bagasse using four different alcohols (methanol, ethanol, n-propanol, and 1-butanol) via the organosolv-CO 2 supercritical pulping process. Langmuir films were characterized by surface... more
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Detection of pathogenic Staphylococcus aureus bacteria by gold based immunosensors
by Claire-marie Pradier and 
2 more
Romain Briandet
Michèle Salmain

2008, Mikrochimica Acta

We describe the elaboration of ultra-sensitive immunosensors, to detect the bacterial pathogen Staphylococcus aureus. We utilized commercially available polyclonal anti-S. aureus antibody as receptor. Immunosensors were elaborated by... more
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Determination of methyl ester contents in biodiesel blends by FTIR-ATR and FTNIR spectroscopies
by Joel Rubim

2006, Talanta

Partial last square regression (PLS) and artificial neural network (ANN) combined to FTIR-ATR and FTNIR spectroscopies have been used to design calibration models for the determination of methyl ester content (%, w/w) in biodiesel blends... more
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Application of ATR-far-infrared spectroscopy to the analysis of natural resins
by SILVIA PRATI

2011, Analytical and Bioanalytical Chemistry

This study proposes FTIR spectroscopy in the farinfrared region (FarIR) as an alternative method for the characterisation of natural resins. To this purpose, standards of natural resins belonging to four different categories and dammar)... more
Fig. 10 PC1/PC2 plot resulting from PCA of the resins FarIR spectra (minimum eight replicates for standards, four replicates for the BP sample); BP historical sample, CF colophony, CP copal, D dammar, E elemi, M mastic, SA sandarac, SH shellac, VE Venice turpentine
Table 1 Natural resins signals in the FarIR region obtained in ATR s strong, m medium, w weak, sh shoulder
Fig. 2. MidIR spectra obtained in ATR of a elemi, b shellac, ¢ colophony, d Venice turpentine, e sandarac, f copal, g dammar, h mastic of organic substances has not yet been carried out. To this purpose, standards of natural resins used as paint varnishes have been analysed by FarIR spectroscopy in ATR mode, obtaining promising results. Moreover, the discrimination between spectral data was magnified and verified using principal component analysis (PCA). Two historical samples have been examined. One (BP) was collected from a yellow area of the “La Battaglia di Cialdiran”, an oil painting on canvas dated back to the sixteenth century, the work of an unknown artist conserved in the Regional Museum of Mirto Palace, Palermo, Italy.
Fig. 1 ATR Smart Orbit™ mounted on a Thermo Nicolet Nexus 5700 spectrometer
Fig. 3. FarIR spectra obtained in ATR of a elemi, b shellac, ¢ colophony, d Venice turpentine, e sandarac, f copal, g dammar, h mastic Spectral data were processed by PCA and employing the chemometric package V-PARVUS. Matrix dataset was com- posed with intensity values of peaks as variables (columns) and spectra in the range 670-150 cm ' as objects (rows). Standard normal variate (SNV) transformation and column centering were applied as a row pre-treatment on the matrix dataset. SNV was specially applied in order to remove slope variation and to correct both baseline shifts and global intensity variations [38]. powder form by grinding the bulk resins, or in small The ATR spectra were registered by a diamond ATR Smart Orbit™ accessory (from Thermo Optec) both in the MidIR (DTGS detector with a KBr window) and in the FarIR (DTGS detector with a polyethylene window) region (Fig. 1). The diamond crystal has a refractive index of 2.4, with a single bouncing refractive infrared beam at 45° angle of incidence. Analyses were performed on samples in a powder form by grinding the bulk resins, or in small
Fig. 4 Cross-section photomicrographs under a visible and b UV light of the KBr embedded BP cross-section (/ayer 2 varnish; layer 1 pigmented layer composed by yellow ochre, lead white, calcite, siccative oil; /ayer 0 preparation composed by gypsum) Previous studies on the characterization of natural resins performed by Raman spectroscopy allowed the approxi- mate assignment of frequency values in the vibrational mode [22-31]. A comparison with the data reported in literature was made to identify possible transitions, which are active both in infrared and Raman spectroscopy. FarIR spectra are indeed different from Raman ones, but there are common absorptions. In particular the following vibrations vu cc 25 6 CCC 24-25,27 r CCO 23-27, 31 6 CCC 24, 31 6 co 31 t (CCC), t (CCO) *4 and t (CH3) ** 7” have been tentatively assigned in Table 1. The presence of vibrational modes active only in the FarlR region further confirms that the two techniques may complement each other in the characterisation of natural resins.
Fig. 5 FarlR spectra obtained in ATR of a BP sample, b dammar (D c yellow ochre (YO): C calcium carbonate Historical samples
Figure 5a shows the BP spectrum in the FarIR region obtained in macro ATR on the external surface (corresponding to layer 2 in Fig. 4). From the MidIR spectrum (not reported) the carboxylic acids band (1,716 cm ') suggests the presence of a natural resin, but its identification resulted rather difficult. The FarIR spec- trum was more informative and when comparing it with the dammar profile (Fig. 5b) different analogies can be noticed in the position and shape of the bands (i.e. bands at 638, 580, 530, 458, 351 cm’). The occurrence of dammar in this sample suggested by FarIR data was supported by analytical pyrolysis. Chromatograms in full scan obtained from off-line pyrolysis of sample BP and dammar are shown in Fig. 6a and b, respectively. A cluster of peaks with retention times and mass spectra corresponding to those of dehydrogenated sesquiterpenes C,5H»2 specific of
Fig. 7 Cross-section photomicrographs under a visible and b UV light of the KBr embedded PMB7 cross-section (/ayer 2 gold varnish, layer I Silver leaf, layer 0 leather)
Fig. 8 FarIR spectra obtained in ATR of a PMB7 sample, b colophony ¢ leather (DIT diterpenic resin without a polymerised component; L leather)
Fig. 9 PC1/PC2 plot resulting from PCA of the resins MidIR spectra (minimum nine replicates for standards, two replicates for the BP sample); BP historical sample, CF colophony, CP copal, D dammar, E elemi, M mastic, SA sandarac, SH shellac, VE Venice turpentine such as dammar, mastic, shellac and elemi, while are not effective for the d polymerised fraction. Moreover, the resins dis between the replicat with the dispersion between different standards (i.e. and Venice turpentine dispersions). Furthermore, not able to correctly identify which resin is present in the historical sample B P. Indeed, the two available re iterpenic resins with or without the persion ed spectra is in some cases comparable mastic PCA is plicates are positioned in a region far from all the analysed resins. This may suggest that the MidIR region is more infl uenced
Table 3 Fisher weights calculated as between classes variance to within class variance ratio for FarIR spectra; BP historical sample; CF colophony; CP copal, D dammar; E elemi; M mastic; SA sandarac; SH shellac; VE Venice turpentine Table 2 Fisher weights calculated as between classes variance to within class variance ratio for MidIR spectra; BP historical sample; CF colophony; CP copal, D dammar; E elemi; M mastic; SA sandarac; SH shellac; VE Venice turpentine this case, PCA is unable to identify the historical sample composition. clusters of different terpenic categories, while the FW of both PC1 and PC2 showed still significant but lower values within classes of resins belonging to the same category, except for colophony and Venice turpentine. Moreover, it was extremely interesting to find out that the low FW values (PC1, 1.1; PC2, 1.2) between the BP sample and the dammar spectra confirm the characterization of the unknown varnish as dammar.
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An FT-IR study of ammonia adsorption and oxidation over anatase-supported metal oxides
by Guido Busca

1997, Applied Catalysis B-environmental

The adsorption and the oxidation of ammonia over sub-monolayer Ti02-anatase supported chromium, manganese, iron, cobalt, nickel and copper oxides, has been investigated using FT-IR spectroscopy. These materials are models of catalysts... more
Fig, 1. FT-IR spectra of adsorbed species on TiO, (anatase) after contact with (a) ammonia (20 Torr) and outgassing at room temperature 3 min; (b) after contact with hydrazine-water vapours (10 Torr) and following outgassing at (c) room temperature, (d) 373 K, (e) 473 K.
Fig. 2. FT-IR spectra of adsorbed species arising from contact of ammonia vapor (20 Torr) with Fe2O3—TiO, (anatase) at room temperature and following outgassing at 300 K (a), 373 K (b) and 473 K (c). J.M.G. Amores et al./Applied Catalysis B: Environmental 13 (1997) 45-58
Fig. 3. FT-IR spectra of adsorbed species arising from contact of ammonia vapor (20 Torr) with CoO,—TiQ, (anatase) at room temperature and following outgassing at 300 K (a), 373 K (b), 573 K (c) and 773 K (d). Contact of ammonia with CoO,-TiO, at room temperature (Fig. 3a) causes the formation of bands These data show that also CoO,—TiO, is a medium- strength Lewis acid solid (bands at 1600 and 1150 cm~', 85,,NH3 and SsymNH3, respectively, of co-ordinated ammonia), with no detectable Brgnsted
Fig. 4. FT-IR spectra of adsorbed species arising from contact of ammonia vapor (20 Torr) with MnO,—TiO> (anatase) (a and b) and NiO,- TiO, (anatase) (c and d) at room temperature and following outgassing at 300 K (a and c), and at 473 K (b and d).
Fig. 5. FT-IR spectra of adsorbed species arising from contact of ammonia vapor (20 Torr) with CrO,—TiO, (anatase) at room temperature in contact with the gas (a) and following outgassing at 300 K (b) 373 K (c) 473 K (d) and 673 K (e). These data show that also NiO,-TiO, and MnO,— TiO, are medium-strength Lewis acids, with no detectable Bronsted acidity. We do not observe intense bands due to partial oxidation products of ammonia here, but adsorbed ammonia species are completely disappeared already after heating at so low a tempera- ture as 473 K, so at a definitely lower temperature with respect to those observed on the above catalysts. This should indicate that these oxides are even more active than the others investigated here in ammonia oxidation to nitrogen, that is per se not detectable but is revealed by the weak band at 2190cm™', assigned to Nz anions. This can be related to the highest activity found, among transition metal oxides, by MnO, in ammonia oxidation [46,47]. The spectrum obtained after evacuation at 373 K is similar to the previous one, although the maximum of
Fig. 6. Absorption bands in the FT-IR spectrum of CrO,—TiO; (anatase) after activation, assigned to Cr=O stretching modes J.M.G. Amores et al./Applied Catalysis B: Environmental 13 (1997) 45-58
Composition of catalysts investigated here 3. Results Table 1 powders, previously pre-treated by calcination in the IR cell at 673 K for 2 h and outgassing at 673 K for 30 min. Ammonia was taken from commercial cylin- ders from SIAD (Milano, Italy). Hydrazine water solution was purchased from Carlo Erba (Milano, Italy).
Wavenumbers (cm7') of the IR absorption bands spectra of hydrazine species Table 2 are nearly superimposed. However, the band due to the 5.4sNHz; of co-ordinated ammonia is found quite broad invariably in the region 1605-1595 cm! [28], while the most intense SNH mode of adsorbed hydrazine is located at or above 1610 cm", is definitely sharper and pointed, and frequently is coupled to a weak sharp peak near 1580 cm~'. Also the lower frequency strong band due to adsorbed hydrazine is sharper than the corresponding one due to co-ordinated ammonia. Finally, weak bands could be observed in between these modes only in the case of adsorbed hydrazine. The spectrum of adsorbed hydrazine in the NH stretching region is certainly more complex than that of adsorbed ammonia. However, the bands are weaker and the radiation in this region can be severely scat- tered, so that the analysis of these modes is quite difficult. In any case, our study of ammonia adsorption on TiO,-anatase do not provide evidence of the for- mation of detectable amounts of hydrazine from ammonia on this surface even at higher temperatures. 1416 cm™' is reported for hydrazinium cations [40], likely due to another deformation mode. We can mention that hydrazine is slightly less basic than ammonia (pK, NHj = 9.24; pK, NH.—NtH; = 7.49 [42]). Previous experiments showed that the co-adsorption of water and _ pyridine (pK, CsHsNH* = 5.25 [42]) on titania caused the appear- ance of pyridinium ions [43]. This is due to the Br@nsted acidity of water, than can be even increased by molecular adsorption. The same occurs with hydra- zine, which is more basic than pyridine, with the formation of hydrazinium ions in the presence of water.
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On the formation and structure of self-assembling monolayers
by Julio Gun

1986, Journal of Colloid and Interface Science

A new approach to the formation of oriented monolayers and the assembling of built-up multilayer films is presented. The new method is fundamentally different from the Langmuir-Blodgett (LB) procedure, being based on the spontaneous... more
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Processing of thin SU-8 films
by Stephan Keller

2008, Journal of Micromechanics and Microengineering

This paper summarizes the results of the process optimization for SU-8 films with thicknesses 5 μm. The influence of soft-bake conditions, exposure dose and post-exposure-bake parameters on residual film stress, structural stability and... more
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Synthesis, Characterization and Swelling Behavior of Gelatin-g-poly(sodium acrylate)/Kaolin Superabsorbent Hydrogel Composites
by Hossein Hosseinzadeh

2007, Journal of Composite Materials

A novel composite hydrogel was prepared via UV irradiation copolymerization of acrylic acid and maize bran (MB) in the presence of composite initiator (2,2-dimethoxy-2-phenylacetophenone and ammonium persulfate) and cross-linker... more
Figure 1. Proposed reaction mechanism for the synthesis of MB— PAA.
Figure 2. SEM micrographs of (a) MB, (b) PAA, and (c) MB—PAA; (d) FTIR spectra of MB, PAA, and MB—PAA; (e) TG curves of MB, PAA, and MB-PAA; (f) DTG curves of MB, PAA, and MB—PAA.
figure 3. (a) Water-retaining capacity of MB—PAA centrifuged at 6000 rpm and dried at 60 °C; effect of (b) maize bran content on AA and (c) eaction time on water absorbency; water absorbency of superabsorbent hydrogel in (d) KCI, NaCl, NH,Cl, CaCl, MgCl, FeCl, and AICI, and (e) NaCl, Na,SO,, and Na;PO, aqueous solutions; (f) salt sensitivity factor of various salts at a concentration of 150 mmol L™’.
Figure 4. (a) Swelling behavior of different hydrogel particle sizes in distilled water absorbency; (b) pseudo-first-order kinetic model; (c) pseudo- second-order kinetic model; (d) water diffusion behavior for different hydrogel particle sizes.
Table 1. Elemental Analysis of MB, PAA, and MB—PAA
Table 2. Effect of Salt Solutions on Water Absorption
The other two (60 mesh and 20 mesh) had similar swelling processes. Table 3. Kinetic Parameters for the Water Absorbency of MB—PAA in Distilled Water larger than that to monovalent anions at the same concentration.
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Gas chromatography with spectroscopic detectors
by Tania Sasaki and 
1 more
Charles Wilkins

1999, Journal of Chromatography A

In recent years, capillary gas chromatography (GC) with Fourier Transform Infrared (FT-IR) and / or mass spectral (MS) detection has become a primary analytical tool for qualitative and quantitative analysis of complex mixtures. Because... more
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Development and Use of an Attenuated Total Reflectance/Fourier Transform Infrared (ATR/FT-IR) Spectral Database To Identify Foreign Matter in Cotton
by David McAlister

2006, Journal of Agricultural and Food Chemistry

The presence of foreign matter in cotton seriously affects the cotton grade and thus the price per bale paid by the spinner to the grower, the efficiency of the spinning and ginning operations, and the quality of the final woven product.... more
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