In-situ lignin modification in acid-alkaline combinational pretreatment on masson pine for efficient biomass saccharification

The recalcitrance of softwood towards enzymatic hydrolysis is one of the major bottlenecks hindering its profitable use as feedstock for lignocellulosic biorefinery. This study presents double in-situ lignin modification in an acid-alkaline combinational pretreatment. Results indicated that complete delignification was not essential to achieve theoretical hydrolysis of cellulose. Alternatively, partial lignin removal accompanied by selective modification of the lignin gave rise to significantly inproved ease of enzymatic hydrolysis. Several analyses, including (GPC, 31 P NMR, 2D HSQC NMR, QCM and DLS) were performed to reveal the underlying mechanism of the double in-situ lignin modification in enhancing ease of cellulose hydrolysis. Moreover, detaching behavior of lignin during enzymatic hydrolysis was also elucidated, which provided new insights into understanding the role lignin repolymerization inhibitors and combinational pretreatments played in improving enzymatic digestibility of lignocellulosic biomass.