It has been become a well-established fact that addition of surfactants to enzymatic hydrolysis of lignocelluloses can increase the conversion of polysaccharide fraction into fermentable sugars (Kumar and Wyman, 2009b). In the present study, although significant increase in hydrolysis yield was obtained for WS pretreated by dilute
acid in combination with Tween 20 (Table 3), there was considerable amount of lignin left in WIS obtained after Tweenassisted dilute acid pretreatment (Table 1), which would negatively affect enzymatic hydrolysis.
Based on the proposed mechanisms on the surfactant effect on pretreatment and enzymatic hydrolysis, enhanced enzymatic convertibility could be expectedif Tween 20 was added during enzymatic hydrolysis of Tweentreated
lignin-containing substrate. Following experiments were carried out to investigate if surfactant could improve the enzymatic conversion of surfactant-assisted dilute acid pretreated WS. Hydrolysis experiments were performed on WS pretreated at conditions enabling maximum cellulose digestibility (2% sulfuric acid combined with 1% Tween 20), which gave the highest yield of glucose and xylose (Table 3).
For comparison, the effect of surfactant on enzymatic hydrolysis of WS pretreated by individual 2% acid was also investigated.