Effect of alkaline pre treatment on solids recovery delignification of Prosopis juliflora

摘要

Prosopis juliora, a thorny shrub and common vegetation of semi-arid region of Indian subcontinent and considered to be as a problematic weed has been suggested recently to use as one of the alternative lignocellulosic biomass materials for long and sustainable production of cellulosic ethanol. However, recalcitrant structure of lignocellulosic material necessitates a pretreatment step to break it up, thus making cellulose and hemicellulose more accessible to hydrolytic enzymes for fermentable sugar production which then fermented to bioethanol. Among all the pretreatment methods, alkaline pretreatment has received greater attention because it is relatively inexpensive and less energy intensive. In the present study, the effect of sodium hydroxide pretreatment on recovery of solids and lignin reduction of Prosopis juliflora was investigated at different temperatures with various concentrations of sodium hydroxide for different residence times. It was observed that, as the severity of pretreatment increased, the more solids were lost in the pretreated sample. The corresponding maximum lignin reductions of 48.39, 67.01 and 74.79 per cent were obtained respectively at 100, 120 and 140 °C, for 1 h, 3.0% NaOH concentrations. Maximum lignin reductions at different temperatures were all obtained at the combinations of highest NaOH concentrations and longest residence times, which indicated a close relationship between pretreatment severity and lignin reduction.