Optimized conditions for saccharification of cotton stalk by alkali pretreatment

Cotton stalk resources are rich in Xinjiang. After pretreating, the cotton stalk can be efficiently hydrolyzed by cellulase. The treatment conditions for the pretreatment of cotton stalk by alkali and alkali/microwave were investigated for comprehensive utilization of cotton stalk waste. The contents of lignin and hemicellulose of cotton stalk were decreased by 60.42% and 35.05% at the following conditions: concentration of NaOH(2%), solid to liquid ratio(1:20), temperature(120℃), time(75 min). And they decreased by 61.31% and 44.78% after alkali/microwave pretreated for 15 min at 700 W. Microwave power has less influence on concentration of cellulose in cotton stalk and reclaim rate of carbohydrate (cellulose + hemicellulose). But it has greater influence on pretreatment time, higher power needs shorter time. Hydrolysis rate reached 20.01% after enzymic hydrolys is for 96 h by alkali pretreatment of cotton stalk. But it reached 20.05% for alkali/microwave pretreatment cotton stalk after 48-h hydrolysis.