Title
Effect of different pretreatment methods of corncob on bioethanol production and enzyme recovery
Authors
NAN XIE NAN JIANGMINGJIA ZHANGWEI QI RONGXIN SU and ZHIMIN HE

Received February 3, 2013
Published Volume 48 Issue 3-4 March-April
Keywords corncob, pretreatment, cellulase, enzyme recycling, adsorption, simultaneous saccharification and fermentation

Abstract
Efficient pretreatment and reuse of cellulase are effective methods to promote the cellulosic bioethanol commercialization. Corncob was used as substrate in this study, and the effects of pretreatment methods, including dilute acid, sodium hydroxide, aqueous ammonia soaking and acid-base coupling (dilute sulfuric acid-aqueous ammonia) on glucose and ethanol concentration were analyzed during pre-hydrolysis and the simultaneous saccharification and fermentation (SSF) process. The influence of each pretreatment on the adsorption and desorption of cellulase and on the recycling effect of cellulase after re-adsorption by the fresh substrate were also discussed. The results showed that acid-base coupling pretreatment was much better than a single acid or alkali pretreatment, i.e. the cellulose content of the corncob substrate reached 73.84% after pretreatment; the desorption percent and recycling percent of cellulase after 96 h of SSF and re-adsorption in the first round was 57.7% and 62.4% respectively; ethanol concentration amounted to 62.0% of the first time in the second round of SSF after the enzyme re-adsorption.