Alkaline Pretreatment Toward Sustainable Biorefinery

Renewable and sustainable bioresource and energy are increasingly becoming the popular mainstream in modern society and economic development. Lignocellulosic biomass with great abundance, functionality, and eco-friendliness has captured extensive attention over the past few decades, especially stimulated by the ever-growing energy crisis and environmental deterioration. Alkaline pretreatment of lignocellulosic biomass is crucial for the efficient and consecutive conversion of biomass, which can not only dissociate lignocellulose into single components with excellent properties but also facilitate its targeted valorization toward green fuels, chemicals, and bio-based functional materials. Nowadays, a variety of alkaline pretreatment technologies have been proposed and developed based on a green and sustainable model, which significantly promotes the evolution of biorefinery. Herein, this chapter overviews the recent progress of four mainstream alkaline pretreatment technologies for lignocelluloses, i.e., alkaline pulping, alkaline hydrogen peroxide (H2O2), ammonia-based pretreatment, and alkaline deep eutectic solvent (DES) pretreatment. Their processing features, adaptability, potentials, and further directions are illustrated. On account of the high value-added conversion and utilization of lignocellulosic biomass in biorefinery, lignin valorization by fabricating bio-based versatile materials is also generalized from the point of emerging application materials, e.g., lignin-based hydrogel, advanced composite materials, and environmental remediation materials. Furthermore, the further prospects and development of alkaline pretreatment of lignocellulose and industrial lignin-derived materials are also briefly outlined. It is believed that myriad attention and efforts for alkaline pretreatment of lignocelluloses will accelerate undoubtedly the boom of lignocellulose biorefinery.