Petri Widsten

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The influence of high defibration temperature on the properties of medium-density fiberboard (MDF) made from laccase-treated softwood fibers

Wood Science and Technology, Sep 15, 2004

This study was carried out to elucidate the effect of defibration temperature in the range 171–20... more This study was carried out to elucidate the effect of defibration temperature in the range 171–202°C on the properties of 12-mm thick MDF boards made without synthetic resins from softwood fibers activated by laccase treatment for the generation of phenoxy radicals on the fiber surfaces. Laccase treatment generated radicals in the fibers. An increase in defibration temperature improved the reactivity

Enzymatic treatments for improved dyeing of solid wood

Holzforschung, Mar 7, 2022

Full penetration-dyed solid wood has the advantage that furniture or other items fabricated from ... more Full penetration-dyed solid wood has the advantage that furniture or other items fabricated from it do not require additional painting or staining. However, anatomical barriers along potential dye infiltration pathways may result in unsatisfactory dyeing in terms of depth of dye penetration or colour intensity and uniformity. Dyed wood items, even those intended for interior use, should also possess a certain degree of water fastness. In the present paper, full-thickness dyeing of radiata pine blocks was achieved with fibre-reactive and direct dyes as well as pine tannin. Leaching of the treated blocks in cold water removed excess dye but the target colours were well retained. Pectinase pre-treatment of wood blocks was shown to increase the uptake of fibre-reactive and direct dyes by tracheid cell walls and the uptake of tannin by rays, resin canals, and tracheid lumina. In the case of a direct dye and pine tannin, pectinase treatment markedly increased the intensity of the target colours. Combining tannin with laccase to achieve covalent bonding of tannin to wood lignin was associated with a small, albeit not statistically significant, shift towards the target colour.

Potential of Lignin as Antioxidant for Thermoplastics and Other Materials

The antioxidant properties of technical lignins have been extensively investigated but there are ... more The antioxidant properties of technical lignins have been extensively investigated but there are still gaps of knowledge that should be filled to facilitate the practical applications of lignins as antioxidants (AOs). In the present investigation, we compared the short-term (60 min) and long-term (48h) AO performance of lignins with different contents of functional groups and lignin model compounds (LMCs) with different aromatic ring substituents in the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*) antioxidant assay. We found some LMCs to quickly expend their AO capacity while others started off slowly but after 48h had consumed more DPPH* per phenolic hydroxyl group. Reaction time was also a factor in the relative AO performance of lignins. For softwood lignins, a higher phenolic hydroxyl content was associated with increased DPPH* reactivity. CatLignin, a thermally treated lignin rich in phenolic units and especially catechol groups, consumed more than twice as much DPPH* than any other lignin during 48h (over two mol/lignin unit of 180 g/mol). CatLignin also had the lowest 60 min half-maximal effective concentration (EC50). In polypropylene, lignins provided better UV protection than commercial primary antioxidants applied at similar loadings. Similarly, the better performance of lignin over commercial AOs was observed against thermal oxidation.

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Treatment of conventional kraft and SuperBatch pulp residual lignins with alkaline hydrogen peroxide

Journal of Pulp and Paper Science, 2004

Des echantillons de lignines residuaires isolees d'une pâte kraft conventionelle de pin et d&... more Des echantillons de lignines residuaires isolees d'une pâte kraft conventionelle de pin et d'une pâte SuperBatch de pin par l'hydrolyse enzymatique ont ete traites par du peroxyde d'hydrogene alcalin afin de comparer leur reactivites. La caracterisation des lignines traitees et non traitees a l'aide des spectroscopies 13 C resonance magnetique nucleaire et infrarouge a transformee de Fourier, ainsi que par des methodes chimiques a revele que les traitements ont entraine la fragmentation d'une partie des anneaux aromatiques des lignines, accompagnee d'une diminution de la teneur en groupes hydroxyl-phenoliques et methoxyl et d'une augmentation de la teneur en groupes carboxyles. La degradation oxydative des noyaux aromatiques a ete plus prononcee chez la lignine de la pâte kraft conventionelle que chez celle obtenue de la pâte SuperBatch. Celle-la a aussi consomme plus de peroxyde et a ete solubilisee en plus grande partie que celle-ci.

Antimicrobial and Flame-Retardant Coatings Prepared from Nano- and Microparticles of Unmodified and Nitrogen-Modified Polyphenols

Polymers, Feb 16, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more

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Tannin-Based Microbicidal Coatings for Hospital Privacy Curtains

Journal of Functional Biomaterials, Mar 27, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more

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Biocarbon from brewery residues as a counter electrode catalyst in dye solar cells

Electrochimica Acta, Feb 1, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Lignin-Based Sunscreens—State-of-the-Art, Prospects and Challenges

Cosmetics, Nov 6, 2020

This review covers the latest developments and challenges in the field of broad-spectrum sunscree... more

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Antibacterial melamine resin surfaces for wood-based furniture and flooring

Progress in Organic Coatings, Jul 1, 2009

Melamine resin coatings are commonly used for particleboard and fiberboard products for interior ... more Melamine resin coatings are commonly used for particleboard and fiberboard products for interior applications such as work surfaces, furniture, and laminated wood flooring. In certain environments such as hospitals and kitchens, high hygienic requirements are set for most surfaces. Despite the comparatively good cleanability of melamine-coated surfaces, there is a need for improving their antimicrobial properties. The present paper discusses

Ozonation of conventional kraft and SuperBatch residual lignins in methanol/water and water

Holzforschung, Jul 7, 2004

Model-free kinetic analysis of melamine–formaldehyde resin cure

Chemical Engineering Journal, Oct 15, 2009

The curing behaviour of an industrial melamine-formaldehyde (MF) resin with four different commer... more The curing behaviour of an industrial melamine-formaldehyde (MF) resin with four different commercial curing catalysts was analyzed from thermal studies using differential scanning calorimetry (DSC) and model-free kinetic (MFK) analysis. For the kinetic study, the mathematical approaches developed by Friedman, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Vyazovkin were used to calculate curing isotherms. With all kinetic approaches the apparent activation energy, E a , depended to some extent on the degree of conversion (˛). Besides being obscured by experimental errors, in some cases higher E a (˛) were calculated with higher catalyst concentrations, illustrating that E a (˛) may not be the only relevant parameter to compare different resin systems. However, E a (˛) was found to be well suited for predicting the isothermal curing behaviour of MF resin. The time required for achieving a certain conversion,˛, was calculated for different temperatures. By comparing the calculated isotherms to experimental isothermal data obtained at 80, 100, and 120 • C it was found that the Vyazovkin approach in its advanced form was best suited to predict the curing kinetics of MF with all catalyst systems tested. By applying DSC-MFK it was possible to detect and characterize the de-blocking behaviour of different catalysts for MF curing. The presented results illustrate that isoconversional methods for kinetic analysis of thermochemical data can be applied to the investigation and optimization of melamine-formaldehyde resins.

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Industrial scale evaluation of cationic tannin as a binder for hardboard

Journal of Adhesion Science and Technology, Mar 14, 2014

ABSTRACT Hardboards (HBs) (wet-process high-density fibreboards) were made in an industrial trial... more ABSTRACT Hardboards (HBs) (wet-process high-density fibreboards) were made in an industrial trial using a binder system consisting of cationic mimosa tannin and laccase or just cationic tannin without any thermosetting adhesive. The boards displayed superior mechanical strength compared to reference boards made with phenol–formaldehyde, easily exceeding the European standards for general-purpose HBs. The thickness swell of most of the boards was slightly greater than the standards would allow, so some optimisation is required in this area. The improved board properties appear to be mainly associated with ionic interactions involving quaternary amino groups in cationic tannin and negatively charged wood fibres rather than to cross-linking of fibres via laccase-assisted formation and coupling of radicals in tannin and fibre lignin.

In-mill removal of TMP whitewater contaminants by biological treatment in an aerobic biokidney used in conjunction with microfiltration and laccase treatment

Nordic Pulp & Paper Research Journal, Aug 1, 2004

The suitability of an aerobic in-mill biokidney for purification of TMP newsprint white water was... more The suitability of an aerobic in-mill biokidney for purification of TMP newsprint white water was investigated. The effects of microfiltration and laccase treatment on the quality of biologically treated white water were also studied. The biokidney showed high (71-92%) removal efficiency for COD, BOD, carbohydrates and lignans. The removal efficiency was moderate (50-66%) for TOC and TS, and low (25-35%) for lipophilic extractives and lignin-like material while the amount of suspended solids (SS) increased by 67% as some of the biomass from the biokidney went into the white water. Microfiltration of biologically treated white water removed a minor part of the remaining contaminants of TMP origin and the bulk of the biomass from the biokidney. The treatment of biologically treated white water with laccase before microfiltration gave a large improvement in removal efficiency for all contaminants originating from the TMP but the material present in the laccase solution caused an increase in COD, BOD and TS. The biomass-based SS from the biokidney and the dissolved material in the laccase solution had a more detrimental effect on the mechanical and optical properties of handsheets prepared with untreated and treated white water than the wood-based contaminants.

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Seasonal variations in the composition and behavior in biological treatment of an effluent from an integrated pulp and paper mill

Nordic Pulp & Paper Research Journal, May 1, 2003

ABSTRACT Seasonal variations in wastewater quality of a pulp and paper mill and its effect on the... more ABSTRACT Seasonal variations in wastewater quality of a pulp and paper mill and its effect on the operation of an activated sludge treatment plant (ASTP) receiving the wastewater were studied. The organic loading of the wastewater varied significantly between seasons, peaking during winter and being at its lowest in summer. The compound group responsible for the variation was carbohydrates while the content of lignin and other organic compound groups showed no season-dependence. Knowledge of the seasonal variation in wastewater carbohydrate content may prove valuable for the operation efficiency of the ASTP, particularly for the aeration section where a high carbohydrate loading may cause problems due to accumulation of filamentous sludge. During a period extending from winter to autumn, COD, BOD, carbohydrates and lignans were effectively (96-99%) removed from the wastewater in the ASTP while lignin was more persistent (73-83% removed). Attempts to further increase the plant&#39;s removal efficiency should thus focus on improving the removal of lignin. Seasonal variations in the removal efficiency were not significant. The carbohydrates were almost completely removed in the equalization basin and aeration basins of the ASTP. The degradation of lignans took place in the aeration basins while lignin was removed mainly in the aeration basins.

Modified and unmodified technical lignins as flame retardants for polypropylene

Holzforschung, Oct 29, 2020

Polyolefins used in building materials and furniture require the use of flame-retardant (FR) addi... more Polyolefins used in building materials and furniture require the use of flame-retardant (FR) additives to improve their fire safety. Such additives should be safe to humans and the environment, and preferably bio-based. In the present work, the FR performance of unmodified and chemically modified technical lignins was compared to that of the ammonium polyphosphate/pentaerythritol (APP/ PER) intumescent system in a polypropylene (PP) matrix. Micro-scale combustion calorimetry (MCC) was used to study the peak heat release rate (PHR), temperature at PHR (T PHR), total heat release (THR) and char yield upon thermal decomposition of milligram-scale specimens. The PP/lignin composites showed up to 41% lower PHR and up to 36% lower THR compared to pure PP as well as large char residues. Based on the same parameters, especially the PP/lignin composites made with modified lignins outperformed the reference PP/APP/PER system and the PP/APP/lignin composites where unmodified lignin was used with APP. The most promising PP/lignin composites were prepared with partially demethylated/demethoxylated and depolymerised kraft lignin ('CatLignin'), modified by the Mannich reaction to a nitrogen content of 13.5%.

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Production of 5-hydroxymethylfurfural and furfural from a mixed saccharide feedstock in biphasic solvent systems

Industrial Crops and Products, Sep 1, 2018

Abstract The industrial platform chemicals 5-hydroxymethylfurfural (HMF) and furfural (FF) were p... more Abstract The industrial platform chemicals 5-hydroxymethylfurfural (HMF) and furfural (FF) were produced from mixed mono- and oligosaccharides in a hydrolysate obtained from the prehydrolysis of radiata pine wood chips. The conversions were performed at high temperatures in an autoclave using either a THF/water biphasic system under both Bronsted and Lewis acid catalysis provided by NaHSO4/ZnSO4, or an acetone/water biphasic system under Bronsted acid catalysis afforded by H3PO4. Treatment in a THF/water system at 160 °C for 90 min gave the highest yields of HMF (40 molar%) and FF (58 molar%), while the best conditions for the acetone-water system were 180 °C/80 min for HMF (36 molar%) and 170 °C/30 min for FF (62% molar%). Yields for HMF and FF were based on respective hexose and pentose saccharide contents of the solids. The results show that mixed saccharide by-products of thermo-mechanical pulping can be converted into furans at moderately high yields by both catalytic systems.

A preliminary study of green production of fiberboard bonded with tannin and laccase in a wet process

Holzforschung, Jun 3, 2009

A gluing method for fiberboard based on laccaseactivated tannin and wood fibers was investigated ... more A gluing method for fiberboard based on laccaseactivated tannin and wood fibers was investigated on a laboratory scale. Oxygen consumption measurements showed that hydrolyzable tannins (tannic acid and chestnut tannin) were more reactive toward laccase than condensed tannins from mimosa and quebracho. Wetprocess hardboard prepared with laccase and the most reactive tannin, tannic acid, had superior mechanical strength compared to controls and boards made with laccase alone or laccase and other tannins. The other tannins did not improve mechanical properties more than laccase treatment alone. The addition of wax to the tannic acid-laccase formulation improved the dimensional stability of the boards enough for them to comply with industrial standards, although wax had a negative impact on the mechanical properties. The results cannot be directly applied to dry-process medium-density fiberboard (MDF) production; however, the positive effects of tannin and laccase on hardboard properties also warrant investigations on the green chemistry of MDF production.

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Using isoconversional kinetic analysis of liquid melamine-formaldehyde resin curing to predict laminate surface properties

Journal of Applied Polymer Science, Aug 15, 2009

The curing kinetics of a liquid melamineformaldehyde impregnation resin were analyzed with differ... more The curing kinetics of a liquid melamineformaldehyde impregnation resin were analyzed with differential scanning calorimetry, and the conversion-dependent activation energy for melamine-formaldehyde curing was estimated with the isoconversional model-free kinetic approach developed by Vyazovkin. The conversion-dependent activation energy was used to extend the predictive power of a response surface model describing the influence of some processing factors (press time and resin composition) in the manufacturing of particleboards coated with melamine-formaldehyde-impregnated papers. By substituting the factor ''press time'' in an RSM established for a press temperature of 170 C by the factor ''conversion'' which is accessible from thermo-chemical analysis, additional information on temperature was incorporated into the model. Model applicability for additional temperatures was evaluated with 12 validation experiments. Although chemical resistance was difficult to model, cleanability was sufficiently well described by only one factor (conversion). Surface gloss depended on both the conversion and catalyst amount and was predicted by a two-factor interaction model (R 2 ¼ 0.95). This study demonstrates that parameters derived from the isoconversional kinetic analysis of liquid resins not only are theoretical descriptors but also have direct practical relevance in the modeling of product properties derived from these liquid resins when used to supplement technological databases. V

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Tannins and Extracts of Fruit Byproducts: Antibacterial Activity against Foodborne Bacteria and Antioxidant Capacity

Journal of Agricultural and Food Chemistry, Nov 4, 2014

The shelf life of fresh fish and meat transported over long distances could be extended by using ... more The shelf life of fresh fish and meat transported over long distances could be extended by using plant-based extracts to control spoilage bacteria. The goals of the present study were to identify plant-based extracts that effectively suppress the main spoilage bacteria of chilled fish and lamb and to assess their antioxidant capacity. The phenolic compounds in woodbased tannins and extracts isolated from byproducts of the fruit processing industry were identified and/or quantified. The total phenol content, but not the flavonoid to total phenol ratio, was strongly associated with higher antibacterial activity against several fish and lamb spoilage bacteria in zone of inhibition and minimum inhibitory concentration assays as well as greater antioxidant capacity in the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical assay. The most promising compounds in both cases, and thus good candidates for antibacterial packaging or antioxidant dietary supplements, were mango seed extract and tannic acid containing mostly polygalloyl glucose type phenols.

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Impact of Wood Type and Defibration Temperature on Laccase Reactivity of Wood Fibers for Fiberboard Manufacture

Treatment of wood fibers with laccase generates phenoxy radicals in the fibers. Cross-linking rea... more Treatment of wood fibers with laccase generates phenoxy radicals in the fibers. Cross-linking reactions involving phenoxy radicals are likely to account for the improved mechanical properties observed when fibers are treated with laccase before being fabricated into fiberboards. Knowledge of the effects of raw material type and defibration conditions on the chemical structure and extent of radical formation in the fibers is therefore important. The type of wood raw material used and defibration temperature have a large impact on the number of radicals that can be formed in the fibers. Hardwood fibers are more reactive than softwood fibers produced at equal defibration temperature. The differences in reactivity between the various hardwood and softwood species, respectively, are not significant. An increase in defibration temperature brings about an increase in laccase reactivity. The magnitude of this increase is larger for hardwoods than for softwoods. The laccase reactivity of fibers depends on the chemical structure of the lignin coming into contact with the enzyme. Depolymerized lignin rich in phenolic hydroxyl groups can be extracted from the fibers with water. The water extractable fiber fraction is far more reactive toward laccase than the remaining water-extracted fibers. An increase in defibration temperature results in an increase in the degree of depolymerization of the fiber lignin. The depolymerization is more extensive for hardwood than for softwood lignin. The surface lignin coverage as determined by ESCA spectroscopy is rather similar for all the fibers studied. The results therefore indicate that the differences in radical formation in different fibers can be traced back to their content of low-molecular weight, water soluble lignin.

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