Recent advances in green pre-treatment methods of lignocellulosic biomass for enhanced biofuel production

Increasing global energy demands requires a versatile approach, prompting many researchers to focus on renewable biofuel from sustainable resources, especially second-generation lignocellulosic biomass. The utilization of lignocellulosic biomass for biofuel production requires proper pre-treatment in biorefinery to increase the reaction rate in the subsequent enzymatic hydrolysis step. Consequently, operational cost, enzymes and other chemical agents consumed and amount of waste produced are reduced. In this review, the latest trends in green pre-treatment methods of lignocellulosic biomass are presented and discussed, spanning the years from 2018 to 2021 and every terrestrial biomass type. Green pre-treatment methods such as ozonolysis, ionic liquids, deep eutectic solvents (DES), organosolv and steam explosion are scrutinized for their optimal process parameters that maximize lignin degradation, hydrolysis sugar yield, as well as minimize reaction time, reagent consumption and energy consumption. The potential of green biofuel production by applying green pre-treatment methods are elaborated, and future perspectives for the utilization of green pre-treatment technology at industrial scale are also presented.