Near-complete removal of non-cellulosic components from bamboo by 1-pentanol induced organosolv pretreatment under mild conditions for robust cellulose enzymatic hydrolysis

Abstract Based on Hildebrand solubility parameter (δ H ) theory, a novel organosolv pretreatment medium (OPM), 1-pentanol (80%, v/v)–water mixture with a δ H value of 27.4 (J/cm 3 ) −1/2 , was discovered. This OPM achieved near-complete removal of non-cellulosic components (hemicellulose 96.2% and lignin 87.8%) from bamboo under mild conditions [130 °C, 20 min, 4% (w/w) H 2 SO 4 ]. For the OPMs with similar δ H values [DMSO (80%, v/v)- and 1-pentanol (80%, v/v)-water, 30.9 vs. 27.4 (J/cm 3 ) −1/2 ] to that of bamboo lignin [28.3 (J/cm 3 ) −1/2 ] used in this study, the effect of the δ h value (contribution of hydrogen-binding force to the δ H ) on lignin removal was also discussed. After overcoming the negative effect of lignin deposits on enzymes with biocompatible soy protein (SP), a decent cellulose enzymatic conversion (EC) of 92.6% was achieved by 1-pentanol (80%, v/v)-water induced organosolv pretreatment at a low cellulase loading (5 FPU/g glucan). This cellulose EC was much higher than those of other OPMs (< 63%) with the δ H values very different from that of bamboo lignin. Integration of organosolv pretreatment with an ideal OPM and enzymatic hydrolysis using SP as an additive can be thereby viewed as a viable way to achieve the robust cellulose EC at low enzyme loading, which shows great potential for improving the economics of organosolv pretreatment-based lignocellulose biorefinery. Graphical abstract