NORMAL-BUTYLAMINE AND ACID-STEAM EXPLOSION PRETREATMENTS OF RICE STRAW AND HARDWOOD - EFFECTS ON SUBSTRATE STRUCTURE AND ENZYMATIC-HYDROLYSIS

Without pretreatment, ground rice straw and hardwood substrates are poorly hydrolysed by cellulase (<10%), even though untreated rice straw has a large pore volume accessible to cellulase (0.5-0.9 ml g-1), while hardwood has a much lower value (0.05 ml g-1). Hence the pore volume accessible to cellulase may be necessary but is not sufficient. Partial acid hydrolysis with explosive decompression (PAHE) removes the hemicellulose and modifies, but does not remove the lignin. PAHE increases the pore volume accessible to cellulase of the hardwood from <0.05 to 0.5-0.6 ml g-1. PAHE at 200 or 220°C removes more than 90% of hemicellulose in both substrates. Pretreatment with n-butylamine (nBA) partially removes the lignin but not the hemicellulose. The latter pretreatment was more effective on rice straw (70% hydrolysis by cellulase in 48 h) than on hardwood (about 40% in 48 h). Both pretreatments greatly increase the initial rate of cellulase hydrolysis of rice straw. © 1990.