Energy Plant Cell Wall Composition And Their Digestibility With Dilute Acid Pretreatment

Concerns about global climate and energy supply lead to seeking a non-petroleum-based fuels. Use of cellulosic-ethanol offers several benefits towards reduction of the greenhouse gas emissions and preventing of the competition with food supplies.Ligno-cellulosic biomass is a natural complex primarily consisting of three biopolymers:cellulose, hemicelluloses and lignin. Biomass recalcitrance is the largest obstacle to emerging cellulosic ethanol biorefineries. The purpose of this study was to identify Miscanthus and rice cell wall composition that influence the effectiveness with a dilute acid pretreatment process.The results showed that cellulose and hemicelluloses contents were varied among Miscanthus tested samples, with a little change in lignin. Compared to Miscanthus, rice is greatly varied in the hemicellulose and lignin contents. With increasing H2SO4 concentrations, total sugar yields were raised in both Miscanthus and rice. Particularly, pentose released from Miscanthus is more than one in rice, and hexose in rice is more than in Miscanthus's. Pretreatment by different acid concentrations, the difference of degradation in the Miscanthus and rice were not much changed. Crystalline cellulose and lignin have a negative effect on the enzymatic hydrolysis. The hemicelluloses, acid soluble lignin and uronic acid contents have a positive effect on the enzymatic hydrolysis. The degradation of the combined acid and alkali treatments showed that hemicelluloses are the crucial factors for biomass degradation in Miscanthus. The results of scanning electronic microscopy showed that major microfibrous cellulose structures remain after acid treatment.Materials which have high rate of enzymatic hydrolysis also have a lower degree of crystallinity, and more xylose. The difference of degradation in the Miscanthus and rice by acid was consistent with pretreatment of alkali.