Deep eutectic solvents for lignin isolation

Deep eutectic solvents (DESs) are recently developed green solvents displaying characteristics, including simple production, reliability, chemical stability, low volatility, and biocompatibility that has caught the eye of researchers recently. This book chapter makes an in-depth review of the recent study on deep eutectic solvents, including its classifications, preparation methods, physicochemical characteristics, factors affecting DES pretreatment, and their applications. Based on the type of DES, molar ratio, type of biomass, reaction time, and reaction temperature, DESs can modify lignin characteristics and satisfy certain criteria. In addition, in this review, an investigation of the function of DESs in lignocellulose pretreatment and lignin isolation was also included. DESs dissolve lignin and provide extracted lignin with characteristics that make it suitable for further processing. This book chapter also discusses recent improvements in lignin extraction via biomass fractionation employing DESs and discusses DES-lignin valorization routes, depolymerization and functionalization.