Enhancement of enzymatic hydrolysis of kapok [Ceiba pentandra (L.) gaertn.] seed fibers with potassium hydroxide pretreatment
Abstract
© Rushing Water Publishers Ltd. 2016. Seed fibers from Cambodian kapok [Ceiba pentandra (L.) Gaertn., Bombacaceae] were investigated as a raw material for bioethanol production. Due to their hydrophobic properties, kapok fibers are resistant to wetting, which hinders enzymatic saccharification by commercial enzyme cocktails. Since the xylan is one of the major sources of the hydrophobicity of the kapok fibers, thus, xylan was selectively removed by potassium hydroxide pretreatment. This pretreatment resulted in significant improvement in enzymatic saccharification of the kapok fibers. Cellulose to glucose conversion by cellulase was 10.3% (30 FPU cellulase/g substrate) only for untreated kapok fibers. In contrast, the conversion rate of the pretreated kapok fibers was 83.2% (30 FPU cellulase/g substrate) and 64.5% (10 FPU cellulase/g substrate) at 48 h hydrolysis. More than 80% of glucose was converted to ethanol at 24 h by Saccharomyces cerevisiae fermentation. These results show that the potassium hydroxide pretreatment for the kapok seed fibers could successfully increase the saccharification and finally, the ethanol conversion yields of the treated samples could reach above 80%.