[Pretreatment of ramie and kenaf stalk for bioethanol production]

Ramie and kenaf were traditional fiber crops in China, but their stalk after decorticating has not been used effectively. The stalk contains a lot of cellulose, and can therefore be used for the production of bioethanol. We studied the effects of different chemical pretreatment on enzymatic digestibility of ramie stalk and kenaf stalk. Ramie and kenaf stalks pretreated with alkali were chosen to produce ethanol using quasi-simultaneous saccharification and fermentation (Q-SSF) process. The results show that for the stalks pretreated with 4% NaOH and 0.02% anthraquinone-2-sulfonic acid sodium salt (AQSS) as catalyzer at 170 degrees C for 1 h, the ethanol concentration could reach 51 g/L after fermentation for 168 h at 18% of solid substrate concentration. By fed-batch to 20% of solid substrate concentration, the ethanol concentration could reach 63 g/L, 77% and 79% of the cellulose conversion could get for ramie stalk and kenaf stalk, respectively. For kenaf stalk pretreated with 5.2% NaHSO3 and 0.2% H2SO4 at 170 degrees C for 1 h, the ethanol concentration and cellulose conversion could reach to 65 g/L and 72%, respectively.