| 1. |
- de Carvalho, Danila Morais, et al.
(författare)
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Cold alkaline extraction as a pretreatment for bioethanol production from eucalyptus, sugarcane bagasse and sugarcane straw
- 2016
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Ingår i: Energy Conversion and Management. - : Elsevier. - 0196-8904 .- 1879-2227. ; 124, s. 315-324
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Tidskriftsartikel (refereegranskat)abstract
- Optimal conditions for the cold alkaline extraction (CAE) pretreatment of eucalyptus, sugarcane bagasse and sugarcane straw are proposed in view of their subsequent bioconversion into ethanol through the semi -simultaneous saccharification and fermentation (SSSF) process (with presaccharification followed by simultaneous saccharification and fermentation, or SSF). The optimum conditions, which are identified based on an experiment with a factorial central composite design, resulted in the removal of 46%, 52% and 61% of the xylan and 15%, 37% and 45% of the lignin for eucalyptus, bagasse and straw, respectively. The formation of pseudo-extractives was observed during the CAE of eucalyptus. Despite the similar glucose concentration and yield for all biomasses after 12 h of presaccharification, the highest yield (0.065 g(ethanol)/g(biomass)), concentrations (5.74 g L-1) and volumetric productivity for ethanol (0.57 g L-1 h(-1)) were observed for the sugarcane straw. This finding was most likely related to the improved accessibility of cellulose that resulted from the removal of the largest amount of xylan and lignin.
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| 2. |
- de Carvalho, Danila Morais, et al.
(författare)
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Hydrothermal and Acid Pretreatments Improve Ethanol Production from Lignocellulosic Biomasses
- 2017
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Ingår i: BioResources. - : NORTH CAROLINA STATE UNIV DEPT WOOD & PAPER SCI. - 1930-2126. ; 12:2, s. 3088-3107
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Tidskriftsartikel (refereegranskat)abstract
- Hydrothermal and acid pretreatments using different acid charges (1.5%, 3.0%, and 4.5% H2SO4) were proposed for eucalyptus, sugarcane bagasse, and sugarcane straw prior to their bioconversion into ethanol using the semi-simultaneous saccharification and fermentation (SSSF) process. The hydrothermal and acid pretreatments were efficient for hemicelluloses removal from eucalyptus (63 to 96%), bagasse (25 to 98%), and straw (23 to 95%) and to remove a substantial amount of lignin from eucalyptus (10 to 34%) and bagasse (10 to 27%). During pretreatments, pseudo-extractives and pseudo-lignin were generated from biomasses. The SSSF was performed in pretreated biomasses using 24 h presaccharification followed by an additional 10 h of simultaneous saccharification and fermentation (SSF). With hydrothermal pretreatment, the eucalyptus presented the highest ethanol production, but only low values for SSSF parameters were obtained, as follows: ethanol yield (0.017 g(ethanol)/g(biomass)), volumetric productivity of ethanol (0.16 g L-1 h(-1)), and ethanol concentration (1.6 g L-1). On the other hand, using acid pretreatment, the straw (pretreated using 4.5% H2SO4) presented the highest ethanol production among the biomasses, assessed based on ethanol yield (0.056 g(ethanol)/g(biomass)), volumetric productivity of ethanol (0.51 g L-1 h(-1)), and ethanol concentration (5.1 g L-1).
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| 3. |
- de Souza, Gustavo B., et al.
(författare)
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Enhancement of eucalypt pulp yield through extended impregnation cooking
- 2018
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Ingår i: Nordic Pulp & Paper Research Journal. - : AB SVENSK PAPPERSTIDNING. - 0283-2631 .- 2000-0669. ; 33:2, s. 175-185
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Tidskriftsartikel (refereegranskat)abstract
- The improvement caused by eucalypt chip impregnation on kraft pulping performance was assessed for terminating the cook at kappa in the range of 15-27 and at controlled residual effective alkali (REA) of 6-8 g/L NaOH. Extended impregnation cooking of eucalypt chips (EIC) increased about 10/0 lignin- and HexA-free screen yield gains in relation to conventional cooking (CC), regardless of kappa number in the range of 15-27. The EIC technology allows for cooking eucalypt wood to kappa number up to 27, without rejects production, but without significant improvement in lignin- and HexA-free screen yield and with larger chlorine dioxide (ClO2) consume during bleaching. The optimum kappa number for both CC and EIC cooking was about 19 with similar refinability and strength properties for both technologies, CC and EIC. It was concluded that extended impregnation cooking is an attractive technique for enhancing bleached eucalypt Kraft pulp yield.
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| 4. |
- Arzami, Anis N., et al.
(författare)
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Narrow-leafed lupin (Lupinus angustifolius L.) : Characterization of emulsification and fibre properties
- 2022
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Ingår i: FUTURE FOODS. - : Elsevier BV. - 2666-8335. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Lupin is among the most promising plant-based food protein sources due to its high protein and fibre content. The fibre fraction, especially from seed coats, is often seen as low in value (discarded as waste or as animal feed) and greater knowledge on its composition and structure are crucial to increase its usefulness. However, only one model of lupin fibre structure exists in the literature. Our sample of Finnish-grown narrow-leafed lupin seed consisted of fibre (43.3%), protein (31.3%), fat (8.1%) and starch (0.2%). According to the sugar analysis, rhamnogalacturonan-I, with branches of arabinan and galactan, constituted the main pectin population in the fibre fraction. A revised model of the overall fibre structure is proposed. At concentrations of 0.75% and 1.0%, both unrefined and defatted flour of whole lupin seeds produced stable suspensions and oil-in-water emulsions, demonstrating their application as potential emulsifiers. This study presents the knowledge and opportunity to support sustainability through the utilization of whole lupin seed for future industrial applications.
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| 5. |
- Berglund, Jennie, et al.
(författare)
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Acetylation and Sugar Composition Influence the (In)Solubility of Plant beta-Mannans and Their Interaction with Cellulose Surfaces
- 2020
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Ingår i: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 8:27, s. 10027-10040
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Tidskriftsartikel (refereegranskat)abstract
- Plant beta-mannans are complex heteropolysaccharides that represent an abundant resource from lignocellulosic biomass. The influence of the molecular motifs of plant mannans on the backbone flexibility, solubility, and the interaction with cellulose was investigated by computational and experimental approaches. The regioselectivity of the acetyl substitutions at C2 and C3 distinctively influenced backbone flexibility in aqueous media, as revealed by molecular dynamic simulations. The molecular weight and degree of acetylation were tailored for two model seed mannans (galactomannan and glucomannan) and compared to spruce acetylated galactoglucomannan. The thermal stability was enhanced with increasing acetyl substitutions, independently of the type of mannan. Dynamic light scattering and atomic force microscopy revealed that the occurrence of galactosylation and a low degree of acetylation (similar to that of native acetylated galactoglucomannans) enhanced solubility/dispersibility of mannans, whereas the solubility/dispersibility decreased for higher degrees of acetylation. Mannan solubility influenced their interactions with cellulose at water-cellulose interfaces in terms of adsorbed mass and viscoelastic properties of the adsorbed mannan layers. Our results reveal that modulating the molecular motifs of plant beta-mannans influences their macromolecular conformation and physicochemical properties, with fundamental implications for their role in the plant cell wall and the design of wood-based materials.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- de Carvalho, Danila Morais, et al.
(författare)
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Comparative Study of Acid Hydrolysis of Lignin and Polysaccharides in Biomasses
- 2017
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Ingår i: BioResources. - : North Carolina State University. - 1930-2126. ; 12:4, s. 6907-6923
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Tidskriftsartikel (refereegranskat)abstract
- Effects of different acid hydrolysis conditions were studied relative to the chemical transformations of lignin in eucalyptus, sugarcane bagasse, and sugarcane straw, and on the transformations of multiple polysaccharides in eucalyptus. The acid hydrolysis using 12 mol/L sulfuric acid followed by acid hydrolysis using approximately 0.41 mol/L sulfuric acid was used as the reference for the lignin and sugar analysis. During acid hydrolysis, the relative amount of lignin increased with longer reaction times and/or greater acid concentrations for all biomasses. The overestimation of lignin in harsher acidic conditions resulted from the summation of lignocellulosic-derivatives (pseudo- lignin) together with lignin itself. Lignin reactions (dissolution/deposition) for bagasse and straw occurred in a greater extent than for eucalyptus, considering similar conditions of acid hydrolysis. The sugar transformation during acid hydrolysis was also investigated for eucalyptus. The sugar content quantified in eucalyptus decreased as the acid concentration and/or reaction time in the second hydrolysis increased. Glucose, galactose, and mannose were more resistant to harsher acidic conditions than xylose and arabinose. However, the most severe conditions (121 degrees C, 90 min, and 6.15 mol/L H2SO4) caused complete sugar degradation.
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| 10. |
- de Carvalho, Danila Morais, et al.
(författare)
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Enrichment and Identification of Lignin-Carbohydrate Complexes in Softwood Extract
- 2020
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 8:31, s. 11795-11804
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Tidskriftsartikel (refereegranskat)abstract
- Lignin-carbohydrate complexes (LCCs) are hybrid structures containing covalently linked moieties of lignin and carbohydrates. The structure and behavior of LCCs affect both industrial processes and practical applications of lignocellulosic biomass. However, the identification of phenylglycoside, benzylether, and gamma (gamma)-ester LCC bonds in lignocellulosic biomass is limited due to their relatively low abundance compared to plain carbohydrate and lignin structures. Herein, we enriched the LCC bonds in softwood galactoglucomannan (GGM)-rich extract fractionated by (1) a solvent (ethanol), (2) enzymes, and (3) physical techniques. Two-dimensional nuclear magnetic resonance (NMR) spectroscopy analysis was used to identify the LCC bonds. Phenylglycoside and benzylether bonds were concentrated in the ethanol-soluble GGM fractions. A benzylether bond was concentrated into GGM fractions containing larger molecules (>500 Da) through physical techniques. The gamma-ester bond was identified in all studied GGM fractions, which is explained by its stability and possible presence in residual xylan. In summary, we demonstrated the potential of the suggested techniques to enrich LCC bonds in softwood extract and improve LCC identification. Such techniques may also enable further studies on the structure and functionality of LCC bonds and open new prospects in the engineering of biomolecules.
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| 11. |
- de Carvalho, Danila Morais, et al.
(författare)
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Impact of birch xylan composition and structure on film formation and properties
- 2020
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Ingår i: Holzforschung. - : Walter de Gruyter. - 0018-3830 .- 1437-434X. ; 74:2, s. 184-196
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Tidskriftsartikel (refereegranskat)abstract
- Commercial birch xylan (CX) and alkali-soluble birch xylan (ASX) were subjected to controlled acetylation and used for film formation in the presence (20% and 40%) or absence of plasticizers (i.e. glycerol, sorbitol and xylitol). Although the content of Klason lignin was similar (1.2-1.4%), the acetylation process was favored by the high-purity CX (97% xylan) over the ASX (89% xylan). On the other hand, the presence of residual pectin heteropolysaccharides rather than xylan in the ASX sample was beneficial for film formation. These heteropolysaccharides seemed to act as natural plasticizers during film formation, allowing the formation of coherent films from ASX, even in the absence of an external plasticizer. The use of plasticizers favored the mechanical properties of films, especially in a dosage of 40%, when plastic behavior was created. Acetylation favored the film formation and slightly improved the mechanical properties of the films, and this improvement was in the same range as that achieved when using 20% plasticizer in non-acetylated ASX.
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| 12. |
- de Carvalho, Danila Morais, et al.
(författare)
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Impact of the chemical composition of cellulosic materials on the nanofibrillation process and nanopaper properties
- 2019
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Ingår i: Industrial crops and products (Print). - : Elsevier. - 0926-6690 .- 1872-633X. ; 127, s. 203-211
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigated the impact of the amounts of lignin and hemicelluloses on cellulose nanofibers (CNFs). Birch and spruce wood were used to prepare holocellulose and cellulose samples by classical methods. To better assess the effect of the chemical composition on the CNF performance and simplify the process for CNF preparation, no surface derivatization method was applied for CNF preparation. Increased amounts of hemicelluloses, especially mannans, improved the defibration process, the stability of the CNFs and the mechanical properties, whereas the residual lignin content had no significant effect on these factors. On the other hand, high lignin content turned spruce nanopapers yellowish and, together with hemicelluloses, reduced the strain-at-break values. Finally, when no surface derivatization was applied to holocellulose and cellulose samples before defibration, the controlled preservation of residual lignin and hemicelluloses on the CNFs indicate to be crucial for the process. This simplified method of CNF preparation presents great potential for forest-based industries as a way to use forestry waste (e.g., branches, stumps, and sawdust) to produce CNFs and, consequently, diversify the product range and reach new markets.
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| 13. |
- de Carvalho, Danila Morais, et al.
(författare)
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Improving the thermal stability of different types of xylan by acetylation
- 2019
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Ingår i: Carbohydrate Polymers. - : ELSEVIER SCI LTD. - 0144-8617 .- 1879-1344. ; 220, s. 132-140
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Tidskriftsartikel (refereegranskat)abstract
- The impact of various degrees of acetylation on improving the thermal stability of xylan isolated from different botanical source has been studied; methylglucuronoxylan from birch and eucalyptus, arabinoglucuronoxylan from spruce and glucuronoarabinoxylan from sugarcane bagasse and straw. The lower molecular weight of nonacetylated methylglucuronoxylan (17.7-23.7 kDa) and arabinoglucuronoxylan (16.8 kDa) meant that they were more soluble in water than glucuronoarabinoxylan (43.0-47.0 kDa). The temperature at the onset of degradation increased by 17-61 degrees C and by 75-145 degrees C for low and high acetylated xylans respectively, as a result of acetylation. A glass transition temperature in the range of 121-132 degrees C was observed for the samples non-acetylated and acetylated at low degree of acetylation (0.0-0.6). The acetylation to higher degrees (1.4-1.8) increased the glass transition temperature of the samples to 189-206 degrees C. Acetylation proved to be an efficient method for functionalization of the xylan to increase the thermal stability.
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| 14. |
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| 15. |
- Halysh, Vita, et al.
(författare)
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Effect of oxidative treatment on composition and properties of sorbents prepared from sugarcane residues
- 2019
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Ingår i: Industrial crops and products (Print). - : ELSEVIER. - 0926-6690 .- 1872-633X. ; 139
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Tidskriftsartikel (refereegranskat)abstract
- Efficient sorbents for the removal of cationic dye were prepared from sugarcane bagasse (stalk) and straw (leaves) by oxidative pre-treatment with hydrogen peroxide (H2O2) in acetic acid. The effects of variables, such as concentration of H2O2, temperature and time on the properties of the fiber sorbents obtained were studied according to a 2(3) full-factorial design. For comparison, an oxidative treatment of sugarcane biomass with glacial acetic acid was also used. The yields of the materials obtained and their chemical composition were characterized and compared. Fourier transform infrared spectroscopy, field-emission scanning electron microscopy and benzene vapor adsorption were used to investigate the structural properties and morphology of the initial materials and sorbents. The sorption of methylene blue dye was used to assess the efficiency of dye removal by the sorbents. The pre-treatment conditions significantly affected the sorbent yield, their chemical composition (contents of cellulose, lignin and ash) as well as their sorption properties. The cellulosic sorbent (C-sorbent) from sugarcane bagasse obtained by pre-treatment with H2O2 in acetic acid and the lignocellulosic sorbent (LC-sorbent) from sugarcane straw obtained by pre-treatment with glacial acetic acid, had the highest sorption capacity for the methylene blue dye. For both types of sorbents, the sorption capacity increased with chemical pretreatment as a result of an increase in pore volume.
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| 16. |
- Morais de Carvalho, Danila, et al.
(författare)
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Isolation and characterization of acetylated glucuronoarabinoxylan from sugarcane bagasse and straw
- 2017
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 156, s. 223-234
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Tidskriftsartikel (refereegranskat)abstract
- Sugarcane bagasse and straw are generated in large volumes as by-products of agro-industrial production. They are an emerging valuable resource for the generation of hemicellulose-based materials and products, since they contain significant quantities of xylans (often twice as much as in hardwoods). Heteroxylans (yields of ca 20% based on xylose content in sugarcane bagasse and straw) were successfully isolated and purified using mild delignification followed by dimethyl sulfoxide (DMSO) extraction. Delignification with peracetic acid (PAA) was more efficient than traditional sodium chlorite (NaClO2) delignification for xylan extraction from both biomasses, resulting in higher extraction yields and purity. We have shown that the heteroxylans isolated from sugarcane bagasse and straw are acetylated glucuronoarabinoxylans (GAX), with distinct molecular structures. Bagasse GAX had a slightly lower glycosyl substitution molar ratio of Araf to Xylp to (0.5:10) and (4-O-Me)GlpA to Xylp (0.1:10) than GAX from straw (0.8:10 and 0.1:10 respectively), but a higher degree of acetylation (0.33 and 0.10, respectively). A higher frequency of acetyl groups substitution at position α-(1 → 3) (Xyl-3Ac) than at position α-(1 → 2) (Xyl-2Ac) was confirmed for both bagasse and straw GAX, with a minor ratio of diacetylation (Xyl-2,3Ac). The size and molecular weight distributions for the acetylated GAX extracted from the sugarcane bagasse and straw were analyzed using multiple-detection size-exclusion chromatography (SEC-DRI-MALLS). Light scattering data provided absolute molar mass values for acetylated GAX with higher average values than did standard calibration. Moreover, the data highlighted differences in the molar mass distributions between the two isolation methods for both types of sugarcane GAX, which can be correlated with the different Araf and acetyl substitution patterns. We have developed an empirical model for the molecular structure of acetylated GAX extracted from sugarcane bagasse and straw with PAA/DMSO through the integration of results obtained from glycosidic linkage analysis, 1H NMR spectroscopy and acetyl quantification. This knowledge of the structure of xylans in sugarcane bagasse and straw will provide a better understanding of the isolation-structure-properties relationship of these biopolymers and, ultimately, create new possibilities for the use of sugarcane xylan in high-value applications, such as biochemicals and bio-based materials.
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| 17. |
- Yilmaz Turan, Secil, et al.
(författare)
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Bio-based films from wheat bran feruloylated arabinoxylan : Effect of extraction technique, acetylation and feruloylation
- 2020
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Ingår i: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344. ; 250
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Tidskriftsartikel (refereegranskat)abstract
- This study demonstrates the potential of feruloylated arabinoxylan (AX) from wheat bran for the preparation of bioactive barrier films with antioxidant properties. We have comprehensively evaluated the influence of the structural features and chemical acetylation of feruloylated AX extracted by subcritical water on their film properties, in comparison with alkaline extracted AX and a reference wheat endosperm AX. The degree of substitution (DS) of AX had a large influence on film formation, higher DS yielded better thermal and mechanical properties. The barrier properties of AX films were significantly enhanced by external plasticization by sorbitol. Chemical acetylation significantly improved the thermal stability but not the mechanical or barrier properties of the films. The presence of bound ferulic acid in feruloylated AX films resulted in higher antioxidant activity compared to external addition of free ferulic acid, which demonstrates their potential use in active packaging applications for the preservation of oxygen-sensitive foodstuff. © 2020 The Author(s)
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| 18. |
- Zanao, Marina, et al.
(författare)
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Evaluation of Kraft-PS Cooking for Eucalypt and Pine Wood Chip Mixtures
- 2019
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Ingår i: Journal of wood chemistry and technology. - : TAYLOR & FRANCIS INC. - 0277-3813 .- 1532-2319. ; 39:3, s. 149-165
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was evaluating polysulfides (PS) as additives in kraft cooking of wood mixtures eucalypt (E) and pine chips (P) wood mixtures, namely: 50E/50P, 70E/30P, and 90E/10P. Bleaching (O(D/A)(EP)D) and refining of pulps were also investigated. The PS addition (1.5 or 3.0%) to the kraft cooking preserved the hemicelluloses resulting increased pulp yield and reduced H-factor. The oxygen delignification was more efficient for chip mixtures containing higher proportion of pine chips, but was not largely affected by the addition of PS. The bleach chemical consumption was not significantly influenced by PS dosage or by the wood chip mixture. The burst and tear indexes were improved by increasing the proportion of pine chips to the mixture, but an opposite effect was observed for refinability, tensile index, and opacity. The kraft-PS pulps showed increased refinability, tensile, and burst strengths in relation the standard pulps, but lower opacities.
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