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Eucalyptus globulus wood samples were subjected to hydrothermal processing according to a three-stage, crossflow scheme with intercalated washing stages. The operational conditions for each hydrothermal stage were selected based on previous experiments, as the kinetics and yields depended on the composition of the reaction media. The solid recovery yields as well as the compositions of the various solids and liquids involved in each stage were measured, in order to allow the formulation of material balances. Under the conditions selected, the various stages enabled solid recovery yields in the range 70.8–74.4 g/100 g oven-dry wood, with extensive hemicellulose removal and almost quantitative recovery of both cellulose and lignin in solid phase. The production of valuable polysaccharide-derived products (including saccharides and furans) along the process decreased owing to the different initial composition of the various reaction media. In turn, the generation of monosaccharides from soluble saccharides of oligomeric or polymeric nature was promoted in the second and third stages. The experimental data provided in this study allow a quantitative assessment on the considered process, a basic information for simulation and economic evaluation. [ABSTRACT FROM AUTHOR]

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Pinus pinaster wood was pulped in ethanol/water medium catalyzed with sulfuric acid, and lignin was recovered from the liquid phase by precipitation upon water addition. Lignin samples were characterized for composition and thermal properties. Lignin samples were reacted with selected esterification agents (butyric, isobutyric, or crotonic anhydrides) under experimental conditions leading to extensive conversion of the available hydroxyl groups, and the esterified lignins were assessed for composition and thermal properties. Samples made up of crude polylactic acid or its blends with lignins (raw or esterified) were assayed for mechanical properties. The blends of polylactic acid with lignin modified with butyric anhydride presented higher Young's modulus and elongation at break than neat polylactic acid. [ABSTRACT FROM AUTHOR]

Xylose solutions have been produced from Eucalyptus globulus wood by autohydrolysis (with hot, compressed water) and post-hydrolysis (in presence of sulfuric acid). This two-stage process led to solids enriched in cellulose and lignin (suitable as a substrate for pulping) and liquors containing xylose as the major component. The liquid phase from post-hydrolysis also contained other sugars (glucose, arabinose) and acetic acid. Neutralized liquors (as obtained, or after membrane concentration), were employed (directly or after detoxification by ion exchange) as fermentation media for the production of hemicelluosic bioethanol with the yeast Pichia stipitis CECT 1922T. Under the best conditions assayed (fermentation of neutralized, concentrated and detoxified two-stage hydrolysis liquors), bioconversion took place at nearly stoichiometric yield, with a volumetric productivity of 0.37 g l-1·h-1. [ABSTRACT FROM AUTHOR]

Summary Orange peel waste (OPW) was evaluated as a raw material for the enzymatic production of pectic oligosaccharides. In a preliminary step, free sugars and other water-soluble compounds were extracted from OPW to obtain a substrate for enzymatic hydrolysis (EHS), to achieve two objectives: (i) removal of sugars and impurities, and (ii) production of a sugar-rich stream suitable for further utilisation, according to the 'biorefinery' philosophy. EHS was treated with hydrolytic enzymes (pectinases and cellulases), and the effects of selected operational variables (enzyme charges and reaction time) on selected dependent variables (measuring the conversions of polysaccharides into mono- and oligosaccharides, and liquor recovery) were assessed. Mathematical models were developed for this purpose. Under selected conditions, the models predicted that 100 kg of EHS yielded 7.5 kg of gluco-oligosaccharides, 4.5 kg of galacto-oligosaccharides, 6.3 kg of arabino-oligosaccharides and 13 kg of oligogalacturonides (contained in 991.6 kg of liquor). [ABSTRACT FROM AUTHOR]

Rice hulls are potential low-cost feedstocks for fuel ethanol production in many countries. Most of the relevant publications are devoted to homogenous (high quality) hulls generated in industrial mills. On the other hand, small-scale mills give rise to hulls containing grain fragments and bran. In the present work, the dilute-acid pretreatment of such heterogeneous rice hulls was investigated based on a central composite rotatable experimental design. The variables were: temperature (140-210°C), biomass load (5-20%), and sulfuric acid concentration (0.5-1.5% based on reaction mixture). A total of 16 experimental runs were carried out, including a 23-plan, two replicates at the central point and six star points. Low temperatures were found to be favorable for the hydrolysis of xylan and of the easily hydrolyzable glucan fraction. High glucose formation (up to 15.3% of the raw material dry weight), attributable to starch hydrolysis, was detected in the hydrolysates obtained under the least severe pretreatment conditions. Several models were developed for predicting the effect of the operational conditions on the yield of pretreated solids, xylan and glucan conversion upon pretreatment, and on enzymatic convertibility of cellulose. The pretreatment temperature exerted the most significant effect on the conversion of the polysaccharides. Optimum results were predicted for the conversion of easily-hydrolyzable glucan in the material pretreated at 140.7°C, and for the enzymatic saccharification of cellulose in the material pretreated at 169°C. These results are interpreted that a two-step acid hydrolysis may be the best pretreatment strategy for heterogeneous rice hulls produced in small mills. [ABSTRACT FROM AUTHOR]