NaOH-Aided Sulfolane Pretreatment for Effective Fractionation and Utilization of Willow (<i>Salix matsudana</i> cv. Zhuliu)
Lei Zhong, Liyuan Yang, Chao Wang, Xingxiang Ji, Guihua Yang, Jiachuan Chen, Gaojin Lyu, Feng Xu, Chang Geun Yoo
Abstract
In this study, the alkaline catalyst (NaOH)-aided sulfolane organosolv pretreatment was first developed to reduce the recalcitrance of willow (Salix matsudana cv. Zhuliu) for effective saccharification and lignin valorization in subsequent processes. The pretreatment notably removed lignin, minimized cellulose loss, and increased the accessibility of cellulose. The sulfolane/water (50/50, w/w) pretreatment with 4% NaOH at 140 °C for 1.5 h increased the glucose saccharification yield by 14.2-fold of the yield from the untreated willow. The recovered lignin had high purity (∼97.0%), well-preserved molecular weight (4300–5010 g/mol), and low polydispersity (∼2.0). NMR analysis of the recovered lignin also indicated that it retained the representative linkage structures (e.g., β-O-4, β–β linkages). Based on these observations, the recovered lignin showed great potential as an intermediate in the production of functional biomaterials and/or green biofuels.