Duarte Neiva

Universidade de Lisboa, Departamento de Engenharia Florestal, Graduate Student

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Papers by Duarte Neiva

Encouraging Invasive Acacia Control Strategies by Repurposing Their Wood Biomass Waste for Pulp and Paper Production

Forests, May 7, 2024

Concerns on the expanding infestation of several Acacia species in the southern Mediterranean Eur... more Concerns on the expanding infestation of several Acacia species in the southern Mediterranean European countries have triggered an ever-growing requirement for costly targeted control actions. Valorizing biomass waste produced could help promote and better finance these actions. For that purpose, wood wastes from invasive control actions were tested regarding their pulp and paper potential, aiming to entice cellulose industries to partake in future conservation actions. Wood waste from the five most pervasive Acacia species was studied (Acacia dealbata Link, Acacia longifolia Willd, Acacia mearnsii De Wild, Acacia melanoxylon R.Br, and Acacia saligna Labill) regarding physical and chemical characteristics, and a central composite design was used to optimize alkali charge and reaction temperature on pulping yield and delignification. Bleached kraft pulps were produced with each species' optimized conditions and for an equitable mixture of all species. Optimized pulp yields (52.6%-53.5%) and pulp polymerization degree (2867-3690) of Acacia species were higher than those of Eucalyptus globulus Labill (used as reference). Optimized bleached pulps were refined and fiber, pulp, and handsheet properties determined. Acacia dealbata and A. longifolia presented high specific wood consumption and lower handsheet strength properties, pointing to overall lower pulping potential, while A. melanoxylon and A. mearnsii characteristics were equal to or higher than those of E. globulus. A. saligna pulp and handsheet characteristics appear more suited for tissue paper. The Acacia mixture achieved acceptable characteristics, enabling the indiscriminate use of Acacia wood regardless of the species. As a shortcoming, the Acacia pulps showed the worst optical characteristics, with brightness dropping substantially with beating (64%-76%) when compared to E. globulus (81%).

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$Research paper thumbnail of Proximate and ultimate analysis (in % o.d. mass) and high heating value (MJ/kg) of the industrial bark (IB) of Picea abies, the wood (W) and bark-only (B) fractions, as well as of three granulometric fractions obtained after grinding and sieving of bark (B1, < 0.180 mm, B3<...$

Proximate and ultimate analysis (in % o.d. mass) and high heating value (MJ/kg) of the industrial bark (IB) of Picea abies, the wood (W) and bark-only (B) fractions, as well as of three granulometric fractions obtained after grinding and sieving of bark (B1, < 0.180 mm, B3<...

Proximate and ultimate analysis (in % o.d. mass) and high heating value (MJ/kg) of the i... more Proximate and ultimate analysis (in % o.d. mass) and high heating value (MJ/kg) of the industrial bark (IB) of Picea abies, the wood (W) and bark-only (B) fractions, as well as of three granulometric fractions obtained after grinding and sieving of bark (B1, < 0.180 mm, B3 (0.25<Φ<0.45 mm) and B6 (2.00<Φ<10.00 mm).</p

$Research paper thumbnail of Chemical composition (total phenolics, flavonoids, condensed tannins) and antioxidant properties (FRAP and DPPH) of the ethanol and water extracts of the industrial bark (IB) of Picea abies, the wood (W) and bark-only (B) fractions, as well as of three granulometric fractions obtained afte...$

Chemical composition (total phenolics, flavonoids, condensed tannins) and antioxidant properties (FRAP and DPPH) of the ethanol and water extracts of the industrial bark (IB) of Picea abies, the wood (W) and bark-only (B) fractions, as well as of three granulometric fractions obtained afte...

Determinations on standards are included for FRAP (ascorbic acid, catechin and gallic ac... more

$Research paper thumbnail of Example of possible fractionation sequence for Picea abies industrial bark biorefinery$

Example of possible fractionation sequence for Picea abies industrial bark biorefinery

Example of possible fractionation sequence for Picea abies industrial bark biorefinery.&... more

Characterisation of the Phenolic Profile of Acacia retinodes and Acacia mearnsii Flowers’ Extracts

Plants

Acacia spp. is an invasive species that is widespread throughout the Portuguese territory. Thus, ... more Acacia spp. is an invasive species that is widespread throughout the Portuguese territory. Thus, it is pertinent to better understand this species in order to find different applications that will value its use. To evaluate the phenolic profile in Acacia flowers, ethanolic extracts obtained through an energized guided dispersive extraction were analysed, focusing on two species, Acacia retinodes and Acacia mearnsii, at two flowering stages. The phytochemical profile of each extract was determined by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and high-performance liquid chromatography coupled with diode array detector. The FTIR-ATR technique was used to distinguish the different samples’ compositions. The results showed the presence of high concentrations of phenolic compounds (>300 mg GAE/g extract), among which are flavonoids (>136 mg QE/g extract), for all combinations of species/flowering stages. The phytochemical p...

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$Research paper thumbnail of Mineral composition (in % o.d. mass or ppm) of the industrial bark (IB) of Picea abies, the wood (W) and bark-only (B) fractions, as well as of three granulometric fractions obtained after grinding and sieving of bark (B1, < 0.180 mm, B3 (0.25<Φ<0.45 mm) and B6</...$

Mineral composition (in % o.d. mass or ppm) of the industrial bark (IB) of Picea abies, the wood (W) and bark-only (B) fractions, as well as of three granulometric fractions obtained after grinding and sieving of bark (B1, < 0.180 mm, B3 (0.25<Φ<0.45 mm) and B6</...

Mineral composition (in % o.d. mass or ppm) of the industrial bark (IB) of Pice... more Mineral composition (in % o.d. mass or ppm) of the industrial bark (IB) of Picea abies, the wood (W) and bark-only (B) fractions, as well as of three granulometric fractions obtained after grinding and sieving of bark (B1, < 0.180 mm, B3 (0.25<Φ<0.45 mm) and B6 (2.00<Φ<10.00 mm).</p

Bio-Refinery Potential of Enset/Ensete ventricosum/Fiber Bundle Using Non-catalyzed and Alkali Catalyzed Hydrothermal Pretreatment

Waste and Biomass Valorization, 2020

Purpose The overall aim of this work is to evaluate bio-refinery potential of Enset fiber. The ef... more Purpose The overall aim of this work is to evaluate bio-refinery potential of Enset fiber. The effect of non-catalyzed and alkali-catalyzed hydrothermal processes was investigated to fractionate Enset fiber bundle. Methods The treatments were made at 130 °C, 150 °C, 180 °C, and 200 °C and the composition of the solids regarding lignin and monomeric sugar and of the liquid phase were evaluated. The treated solid was further delignified by using ethanol alkali pulping at 40% ethanol concentration, 15% alkali concentration, 140 °C, 60 min. Results Temperature-dependent mass loss was observed in both non-catalyzed and catalyzed treatment. The liquor was rich in oligosaccharides with a maximum recovery achieved with the alkali-catalyzed hydrothermal treatment at 130 °C for GOS (12.4 g/100 g of original dry sample) and at 180 °C for XOS (3.4 g/100 g of original dry sample). The fibrous nature of the material was preserved after the treatment. The maximum pulp yield of treated Enset fiber was found to be 61.0% per original sample which is comparable to pulping of original sample 69.1%. Conclusion Therefore, the hydrothermal treatments can be applied as a first fractionation step in the valorization of Enset fibers, allowing the subsequent use of the solid as a fiber source for pulping.

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Hydroxystilbene Glucosides Are Incorporated into Norway Spruce Bark Lignin

Plant Physiology, 2019

Recent investigations have revealed that, in addition to monolignols, some phenolic compounds der... more Recent investigations have revealed that, in addition to monolignols, some phenolic compounds derived from the flavonoid and hydroxystilbene biosynthetic pathways can also function as true lignin monomers in some plants. In this study, we found that the hydroxystilbene glucosides isorhapontin (isorhapontigenin-O-glucoside) and, at lower levels, astringin (piceatannol-O-glucoside) and piceid (resveratrol-O-glucoside) are incorporated into the lignin polymer in Norway spruce (Picea abies) bark. The corresponding aglycones isorhapontigenin, piceatannol, and resveratrol, along with glucose, were released by derivatization followed by reductive cleavage, a chemical degradative method that cleaves b-ether bonds in lignin, indicating that the hydroxystilbene glucosides are (partially) incorporated into the lignin structure through b-ether bonds. Twodimensional NMR analysis confirmed the occurrence of hydroxystilbene glucosides in this lignin, and provided additional information regarding their modes of incorporation into the polymer. The hydroxystilbene glucosides, particularly isorhapontin and astringin, can therefore be considered genuine lignin monomers that participate in coupling and crosscoupling reactions during lignification in Norway spruce bark.

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The effect of different pre-treatments to improve delignification of eucalypt stumps in a biorefinery context

Bioresource Technology Reports

Abstract E. globulus stumps are recently considered as feedstock for pulp industries. Pre-treatme... more Abstract E. globulus stumps are recently considered as feedstock for pulp industries. Pre-treatments may improve delignification, increase pulp quality and promote other cellulosic applications. Five environmentally friendly pre-treatments were studied: liquid hot water (LHW), oxalic acid (OA), alkaline peroxide (AHP), sodium xylenesulfonate (SXS) and iron (III) chloride (FeCl3). The pre-treatments presented different yields: 94.7% (LHW), 92.7% (OA), 79.0% (AHP), 74.8% (SXS) and 78.9% (FeCl3). The chemical composition and FTIR analysis, including infrared structural ratios, of the pre-treated solids showed changes in cell wall structure. OA, SXS and FeCl3 pre-treatments were more selective for hemicelluloses extraction. Mass loss and pulp yield occurred considerably with AHP (21.0%; 53.9%), SXS (25.2%; 46.0%) and FeCl3 (21.1%; 30.7%). The pre-treated material was delignified by the kraft process, bleached using an ECF sequence (D0E1D1E2D2), and the pulp properties were evaluated. LHW improved the pulp physical properties while OA, AHP and SXS showed potential for production of dissolving pulps.

Optimization of ethanol-alkali delignification of false banana (Ensete ventricosum) fibers for pulp production using response surface methodology

Industrial Crops and Products

Abstract The present study investigated the delignification of false banana (Ensete ventricosum) ... more Abstract The present study investigated the delignification of false banana (Ensete ventricosum) fibers obtained as a crop residual material using sulfur-free ethanol-alkali pulping. Response surface methodology with central composite experimental design was used to evaluate the effects of four independent process variables (pulping temperature, time, ethanol concentration and alkali concentration) on pulp yield, kappa number, brightness, whiteness and yellowness of pulp. The major parameters influencing pulp yield and kappa number were found to be the alkali concentration followed by temperature. For the predicted optimal pulping conditions, the pulp yield was 69.9% with 4.9 kappa number and 64.5% brightness. The ethanol-alkali pulp obtained at center conditions was characterized by viscosity and strength properties and compared with Kraft pulp, showing comparable burst, tensile strength and tear strength. Results suggest that the valorization of the Enset fibers for production of well delignified, high yield and resistant pulp is a promising approach.

Characterization of Cynara Cardunculus L. Lignin by Py- GC/MS(Fid)

Four outstanding Cynara cardunculus L. plants were selected from two field experiments located in... more Four outstanding Cynara cardunculus L. plants were selected from two field experiments located in Sesimbra (Portugal) and Alcalá de Henares (Spain), and used for vegetative propagation, producing four clones. In this work, two plants from each clone were collected. The plant stalks were separated in depithed stalks (Stalks DP) and pith (P) samples, for lignin characterization by Py-GC/MS(FID). The lignin derivative compounds with more expression were: 4-vinylsyringol (with values from 1.8% to 5.7%), 4-propenylsyringol (1.7% to 2.5%), syringol (0.63% to 1.9%), 4-methylguaiacol (0.56% to 1.7%), 4-vinylguaiacol (0.21% to 1.1%). The total lignin represented in average 23.9% in depithed stalks, slightly higher than in the pith samples (21.8%). The syringyl-units were predominating in both depithed stalks and pith, with average values of respectively, 12.6% and 13.9%. The depithed stalks samples presented more guaiacyl-units (11.1%), while in pith samples only 7.9% was attained. The p-hyd...

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Kraft Pulping and Wood Chemical Composition for 12 Eucalyptus Species

ABSTRACT There are more than 700 species of eucalypts worldwide although only a few are suited an... more ABSTRACT There are more than 700 species of eucalypts worldwide although only a few are suited and used as pulpwood. In this work we compared the delignification yield and Kappa number of pulps obtained from 12 eucalypt species. We also conducted and compared the chemical analysis regarding ash, extractives, lignin and holocellulose contents, as well as carbohydrate composition. Samples of and E. ovata, with six years of age, were collected from an eucalypt arboretum in Portugal. In terms of yield and kappa number the highest and lowest results were obtained for E. globulus (η=49%, K=12) and E. camaldulensis (η=38%, K=23), respectively. The chemical analysis showed significant variation among species, which in some cases reached differences in the order of magnitude of six to seven times. The overall results suggest that E. globulus is the best species among the 12 in terms of the pulping characteristics studied. E. ovata, and E. saligna also showed good results.

Lignin Characterization of Teak Wood from Mature Trees from East Timor by Py-GC/MS (Fid)

Tectona grandis trees with 70-years of age were collected in East Timor. The heartwood and sapwoo... more Tectona grandis trees with 70-years of age were collected in East Timor. The heartwood and sapwood were characterized by analytical pyrolysis (Py-GC-MS/FID). Heartwood and sapwood presented similar lignin content (37.3% vs. 35.4%). Regarding lignin composition both presented a high values for guaiacyl-units (in average 20.3%), while syringyl-units represented 16.4% in heartwood and 14.4% of total area in sapwood. The phydroxyphenyl-units only amounted to 0.7%. Teakwood is characterized by a GS type of lignin, with a S/G ratio of 0.8. The major lignin derivative compounds found in the pyrograms were: 4-vinylsyringol, trans-coniferyl alcohol, coniferaldehyde, 4-vinylguaiacol, 4-methylguaiacol, vanillin, and sinapinaldehyde, with respectively, 6.6%, 4.5%, 2.0%, 1.6%, 1.6%, 1.5% and 1.2%. The high content of lignin and its composition, with a predominance of guaiacyl-units, leading to a lignin with a more condensed structure, may explain the wood stiffness and resistance to biological attack.

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Chemical composition and kraft pulping potential of 12 eucalypt species

Industrial Crops and Products, 2015

Eucalypts are among the most important short-rotation hardwoods, planted worldwide for the pulp a... more Eucalypts are among the most important short-rotation hardwoods, planted worldwide for the pulp and paper industry. Even though the genus comprises over 700 species, only about a dozen species are used for pulping purposes, therefore, showing the potential for diversification. Six-year-old eucalypt trees from 12 species (Eucalyptus botryoides, Eucalyptus camaldulensis, Eucalyptus globulus, Eucalyptus grandis, Corymbia maculata, Eucalyptus ovata, Eucalyptus propinqua, Eucalyptus resinifera, Eucalyptus rudis, Eucalyptus saligna, Eucalyptus sideroxylon, and Eucalyptus viminalis) were analyzed for chemical composition, fiber morphological, pulping and handsheet paper properties to determine their kraft pulping suitability. The 12 species showed substantial differences regarding extractives (6.1-18.9%), lignin (21.6-30.8%) and holocellulose content (55.4-70.1%). The high inter-species variation in chemical composition produced pulps with different yields (between 38.9 and 49.8%) and degree of delignification (kappa number between 11.6 and 24.2). The combination of these results with the morphological and handsheet properties suggests that E. globulus, E. ovata, E. grandis, E. saligna and E. botryoides have the best overall characteristics for kraft pulping.

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Pulping potential of young eucalypts : a comparative study of wood and pulp properties of 12 eucalypt species

The Eucalyptus genus includes over 700 species and hybrids, of which a few are among the most imp... more The Eucalyptus genus includes over 700 species and hybrids, of which a few are among the most important hardwoods used worldwide for the pulp and paper industry. The large biological variety of the genus suggests a very strong possibility for diversification, which meets a present goal for forests and natural resources. Wood from 6-year-old trees of Eucalyptus botryoides, E. camaldulensis, E. globulus, E. grandis, E. maculata, E. ovata, E. propinqua, E. resinifera, E. rudis, E. saligna, E. sideroxylon and E. viminalis, was used for chemical and pulping experiments. The summative chemical composition showed substantial differences between species: extractives content varied from 6% (E. viminalis, E. globulus and E. ovata) to 19% (E. camaldulensis), lignin content from 22% (E. maculata) to 31% (E. resinifera), and holocellulose content from 55% (E. camaldulensis) to 70% (E. globulus). Kraft pulping was conducted in microdigestors. E. globulus showed the highest yield (50%) and residua...

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Tree bark characterization envisioning an integrated use in a biorefinery

Biomass Conversion and Biorefinery

Lignin from Tree Barks: Chemical Structure and Valorization

ChemSusChem

Abstract Lignins from different tree barks, including Norway spruce (Picea abies), eucalyptus (Eu... more Abstract Lignins from different tree barks, including Norway spruce (Picea abies), eucalyptus (Eucalyptus globulus), mimosa (Acacia dealbata) and blackwood acacia (A. melanoxylon), are thoroughly characterized. The lignin from E. globulus bark is found to be enriched in syringyl (S) units, with lower amounts of guaiacyl (G) and p‐hydroxyphenyl (H) units (H/G/S ratio of 1:26:73), which produces a lignin that is highly enriched in β‐ether linkages (83 %), whereas those from the two Acacia barks have similar compositions (H/G/S ratio of ≈5:50:45), with a predominance of β‐ethers (73–75 %) and lower amounts of condensed carbon–carbon linkages; the lignin from A. dealbata bark also includes some resorcinol‐related compounds, that appear to be incorporated or intimately associated to the polymer. The lignin from P. abies bark is enriched in G units, with lower amounts of H units (H/G ratio of 14:86); this lignin is thus depleted in β‐O‐4′ alkyl–aryl ether linkages (44 %) and enriched in condensed linkages. Interestingly, this lignin contains large amounts of hydroxystilbene glucosides that seem to be integrally incorporated into the lignin structure. This study indicates that lignins from tree barks can be seen as an interesting source of valuable phenolic compounds. Moreover, this study is useful for tailoring conversion technologies for bark deconstruction and valorization.

Fractionation and valorization of industrial bark residues by autohydrolysis and enzymatic saccharification

Bioresource Technology Reports

Potential of Mild Torrefaction for Upgrading the Wood Energy Value of Different Eucalyptus Species

Forests

Torrefaction is a promising pre-treatment for improving the fuel quality of biomass. This study e... more Torrefaction is a promising pre-treatment for improving the fuel quality of biomass. This study examined the effect of a mild torrefaction (from 160 to 230 °C) on the heating value, elemental composition, and thermogravimetric analysis of wood from eight Eucalyptus species (E. botryoides Sm., E. globulus Labill., E. grandis W.Hill ex Maiden, E. maculata (Hook.) K.D. Hill & L.A.S.Johnson, E. propinqua Maiden Deane, E. rudis Endl., E. saligna Sm., and E. viminalis Labill.). The higher heating values (HHV) increased from the initial average of 19 MJ kg−1 to 21 MJ kg−1 in the torrefied samples. The carbon content increased from 48.2% to 53.3% and the C/O ratio from 1.08 to 1.35. The torrefied wood samples showed more thermal stability with a shift of the mass loss peaks to higher temperatures and a higher residual mass at 450 °C of 36%, in comparison to 30% of the untreated samples. Torrefaction concentrated the biomass samples in the more energetic and thermal resistant components and ...

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Bark residues valorization potential regarding antioxidant and antimicrobial extracts

Wood Science and Technology

Bark residual side streams from industries ( Eucalyptus globulus —Eg and Picea abies —Pa) or from... more Bark residual side streams from industries ( Eucalyptus globulus —Eg and Picea abies —Pa) or from control of invasive species in Mediterranean countries ( Acacia melanoxylon —Am and Acacia dealbata —Ad) are burned for energy production, although their high content of extractable compounds points to a possible valorization as sources of phytochemicals with antioxidant and antimicrobial activities. Non-polar and polar extracts were obtained, and their phenolic contents, antioxidant activity, antiquorum sensing and antimicrobial potential against several human pathogenic microbes (nine bacteria and two yeasts) were determined. Extraction yield ranged from 0.5 to 37% of barks dry weight varying with species and solvent used, and both water and ethanol extracts presented strong or very strong scavenging antioxidant ability. Eg and Pa non-polar extracts showed the lowest minimum inhibitory concentration for gram-positive bacteria (0.04–1.25 mg/mL), while Ad presented the best results among polar extracts regarding bacteria (0.16 mg/mL for K. pneumoniae ) and yeast strains (0.02–0.04 mg/mL). Non-polar extracts showed great response against both Candida species (MIC = 0.04–0.63 mg/mL). Each extract had different antimicrobial activity showing that species and solvents can be used to tailor compounds to target specific pathogens. Information regarding these bioactive extracts from residual forest side streams can provide possible utilization routes for natural compounds recovery prior to combustion.

Duarte Neiva

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