Study on the effect of phenoxyethanol–citric acid pretreatment for the enzymatic hydrolysis of bamboo residues

This study investigated the biphasic phenoxyethanol-citric acid (PECA) pretreatment for bamboo residues (BRs) and its corresponding effects on the enzymatic hydrolysis performance. It is found that increasing the concentration of citric acid in the pretreatment system from 2.5% to 15% greatly enhanced the delignification and xylan removal for BRs. Consequently, the enzymatic hydrolysis yield of pretreated BRs significantly enhanced, increasing from 12.4% to 58.2% and 28.0%72.4% when the concentration of citric acid was increased from 2.5% to 15.0% at 160°C and 170°C, respectively. The characterization results from cellulose crystallinity, accessibility, and hydrophobicity of pretreated bamboo residues indicated that their changes possessed a beneficial performance on the enzymatic hydrolysis yield, which could result from the synergistic removal of lignin and xylan. The Chrastil model analysis showed that pretreatment at higher conditions resulted in the pretreated BRs possessing weaker diffusion resistance for cellulase, which is attributed to its higher enzymatic hydrolysis yield.