Study on the optimum process of acid-catalytic ethanol pretreatment of Chinese triploid poplar to enhance sugar recovery by hydrolysis

Abstract

Organosolv pretreatment was applied to Chinese triploid poplar using the acid-catalysis ethanol method to enhance sugar recovery in enzymatic hydrolysis. A Box-Behnken design (BBD) was used to optimize the effect of temperature, ratio of wood to liquor, ethanol concentration, and holding time on the pretreatment process. All variables except for lignin content were found to significantly affect the cellulosic yield as well as crystallinity index (CrI). Quadratic polynomial equations were used to model on the cellulosic yield, CrI, and lignin content for a regression analysis, using response surface methodology (RSM). The optimum process of organosolv pretreatment of Chinese triploid poplar was found to be: temperature: 185 °C, ratio of wood to liquor: 1 to 4.2, ethanol concentration: 45%, and holding time: 41 min. The solid pretreated under optimum process conditions was evaluated for bioconversion using enzymatic hydrolysis of the cellulose fraction to glucose. Approximately 87% of the total cellulose in the poplar was recovered as monomeric glucose after hydrolysis of the solid fraction.