EFFECTS OF SULFITE-FORMALDEHYDE COOKING ON IMPROVING ENZYMATIC HYDROLYSIS OF RICE STRAW

The low cost agricultural residue such as rice straw is abundant in China. It is of great value to develop economic techniques on the pretreatment of rice straw for bioethanol production. Rice straw (Oryza saliva L.) was pretreated by sodium sulfite-formaldehyde (SF) at different Na2SO3 charges and temperatures. The pretreated materials were hydrolyzed with different enzyme dosages to evaluate the effects of pretreatment on sugar yield improvement. The results showed that SF pretreatment at 150 degrees C is a bit more effective than that at 160 degrees C, as a higher pulp yield can be obtained at similar residual lignin content. Increasing the Na2SO3 charge of SF also obviously enhanced enzymatic hydrolysis of cellulose and hemicellulose. A total sugar recovery of 42% on the basis of original rice straw could be obtained after rice straw was pretreated with 16% Na2SO3 charge at 150 degrees C for 1 h.