| 1. |
- 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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| 2. |
- de Carvalho, Danila Morais, et al.
(författare)
-
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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