Abstract:

Bioconversion of fuel ethanol from lignocellulose, the most abundant renewable raw materials on earth, is significant to reduce the greenhouse effect, relieve the energy crisis and enhance the environmental quality. Kenaf is a traditional quick-growing fiber crop with high yields and is considered one of potential materials for fuel ethanol. Four different pretreatment methods for kenaf stalk were studied. Hot water (121℃, 60 min), dilute H2SO4 (3% v/v, 121℃, 60 min), aqueous sodium hydroxide (1.5% w/v, 121℃, 60 min) and microbial pretreatment in solid state cultivation by the white-rot fungus P. sajor-caju were employed in this study to determine how each method affected the digestibility of kenaf stalk during subsequent enzymatic hydrolysis. The results showed that the average conversion rate of NaOH pretreated kenaf sample to fermentable reducing sugar was 82.24 %, and alkaline pretreatment was considered more suitable for kenaf stalk, compared to other three methods. Although efficient delignification and considerable improvement of cellulose digestibility had been reported from kenaf lignocellulose pretreated by the white-rot fungus P. sajor-caju, long pretreatment time and loss of holocellulose still remained as the major weakness of microbial pretreatment, used as an auxiliary pretreatment process for kenaf stalk.