Enzymatic hydrolysis of wheat straw under pretreatment by combining ionic liquid dissolution with alkali extraction

Combining with ionic liquid 1-butyl-3-methylimidazolium chloride([BMIM]Cl) and alkali on pretreatment of wheat straw,the effect of different pretreatment processon the enzymatic hydrolysis of wheat straw was studied. The results show that when 3 gram of primary wheat straw without alkali treatment is dissolved at 130℃ in [BMIM]Cl,the processing time is 15h; when 4 gram of wheat straw pretreated with alkali is dissolved in [BMIM]Cl,the processing time is 10 h only,with the dissolution time greatly reduced. Solubility of primary wheat straw without alkali treatment is 4.50% in ionic liquid [BMIM]Cl after 15 hours; solubility of wheat straw pretreated with alkali is 6.01% after 10 h. The experiment for enzymatic hydrolysis shows that different pretreatment process has a great effect on enzymatic hydrolysis rate,the enzymatic hydrolysis rate of wheat straw pretreated with alkali alone being 70.7%,while the enzymatic hydrolysis rate of wheat straw pretreated by alkali extraction and ionic liquid being 95.3%,the latter is much greater than the former. Furthermore the enzymatic hydrolysis rate of wheat straw pretreated by ionic liquid was only 26.9%,showing a lowest enzymatic hydrolysis rate. A conclusion was summarized that the alkali pretreatment play a role in partly delignification,reducing crystallinity and increasing fi ber surface-area,so as to increase the following enzymatic hydrolysis rate of wheat straw.