Microwave-assisted alkali pre-treatment of wheat straw and its enzymatic hydrolysis

Microwave-assisted alkali pre-treatment of wheat straw and its enzymatic hydrolysis were investigated and compared with the conventional alkali pre-treatment process. First, the effect of microwave power and pretreatment time on the weight loss and composition of wheat straw was examined. The results show that the higher microwave power with shorter pre-treatment time and the lower microwave power with longer pretreatment time had the same effect on the weight loss and composition at the same energy consumption. The comparison was then made between the effect of the microwave-assisted alkali pre-treatment and the conventional alkali one on the weight loss and composition of wheat straw. The wheat straw had a weight loss of 48.4% and a composition of cellulose 79.6%, lignin 5.7% and hemicellulose 7.8% after 25 min microwave-assisted alkali pre-treatment at 700 W, compared with a weight loss of 44.7% and a composition of cellulose 73.5%, lignin 7-2% and hemicellulose 11.2% after 60 min conventional alkali pre-treatment. The microwave-assisted alkali pre-treatment removed more lignin and hemicellulose from wheat straw with shorter pretreatment time compared with the conventional alkali one. Finally, the enzymatic hydrolysis of pre-treated wheat straw (substrate concentration 50 gl(-1), enzyme loading 20 mg g(-1) substrate) was also investigated and the results indicate that the microwave-assisted alkali pre-treated wheat straw had higher hydrolysis rate, reducing sugar concentration and glucose content in the hydrolysate than the conventional alkali pre-treated one. Microwave-assisted alkali pre-treatment is a potential alternative of wheat straw pre-treatment for its enzymatic hydrolysis. (c) 2006 IAgrE. All rights reserved Published by Elsevier Ltd.