Optimizing monosaccharide production from liquid hot water pretreatment and enzymatic hydrolysis of grass-clover press cake.

In the present study, clover-grass press cake was treated by liquid hot water at temperatures of 180-200 °C for a reaction time of 5-10 min. Evaluation of pretreatments was based on the monosaccharide yield after enzymatic hydrolysis of the pretreated slurry and solid fraction, respectively. Extraction of up to 48% hemicellulose and 4% cellulose was observed during pretreatment. The optimal pretreatment conditions were identified as 190 °C and 10 min resulting in monosaccharide yields of 90% and 73% of the theoretical maximum by slurry and solid conversion, respectively. At optimal conditions, the C6 monosaccharide yield (83-90%) was fairly equal compared to the C5 monosaccharide yield (56-89%), which increased by slurry conversion due to near-complete monomerization of soluble xylo-oligosaccharides. In this study, we showed that clover-grass press cake possesses considerable potential as feedstock for production of fermentable sugars in a biorefinery context.

Optimizing the conditions for hydrothermal liquefaction of barley straw for bio-crude oil production using response surface methodology.

The present paper examines the conversion of barley straw to bio-crude oil (BO) via hydrothermal liquefaction. Response surface methodology based on central composite design was utilized to optimize the conditions of four independent variables including reaction temperature (factor X1, 260-340°C), reaction time (factor X2, 5-25min), catalyst dosage (factor X3, 2-18%) and biomass/water ratio (factor X4, 9-21%) for BO yield. It was found that reaction temperature, catalyst dosage and biomass/water ratio had more remarkable influence than reaction time on BO yield by analysis of variance. The predicted BO yield by the second order polynomial model was in good agreement with experimental results. A maximum BO yield of 38.72wt% was obtained at 304.8°C, 15.5min, 11.7% potassium carbonate as catalyst and 18% biomass (based on water). GC/MS analysis revealed that the major BO components were phenols and their derivatives, acids, aromatic hydrocarbon, ketones, N-contained compounds and alcohols, which makes it a promising material in the applications of either bio-fuel or as a phenol substitute in bio-phenolic resins.