Pyro-assisted deep eutectic solvents pretreatment of lignocellulosic biomass: A review

Deep eutectic solvents (DESs) are recognized as promising environmentally friendly solvents for lignocellulosic biomass (LCB) pretreatment, especially considering their excellent solubility for lignin and easy fabrication. In general, the traditional heating approaches provide limited energy in the DESs pretreatment process, resulting in long treatment time and incomplete removal of lignin. Instead, advances in the development of pyro-assisted DESs technology highlight the remarkable synergy of DESs with microwave, ultrasonic, and hydrothermal treatment to endow the integrated processes with superior performance for corresponding pretreatment systems. This review presents the combination of DESs and pyro-assisted pretreatment technology to enhance the LCB deconstruction efficiency, and the state-of-the-art protocols developed for the pretreatment of LCB are showcased. In addition, the unique properties and preparation methods of DESs, and the mechanisms of LCB pretreated with pyro-assisted DESs are also discussed. Efforts are further made to clarify the technical/economic impact of this integrated multi-technology strategy.