Deep eutectic solvents (DESs) in lignocellulosic biomass pretreatment: Mechanisms and process optimization

The urgent transition from fossil-based resources to renewable alternatives has driven extensive research into lignocellulosic biomass as a sustainable feedstock for biofuels and chemicals. Deep eutectic solvents (DESs) have emerged as an innovative pretreatment technology that enhances delignification and facilitates the fractionation of lignocellulosic biomass. This study critically evaluates recent advancements in DES formulations and the mechanisms underlying their interactions with structural components of biomass. As tunable solvents, DESs enable the selective solubilization of cellulose while preserving the structural integrity of hemicellulose and lignin. The efficiency of DES pretreatment can be further improved through the optimization of reaction parameters and the integration of various intensification technologies. This review highlights the crucial role of reaction parameters in enhancing pretreatment efficiency. Additionally, it examines how the incorporation of intensification technologies further enhances DES-based pretreatment by modifying biomass structure, thereby facilitating greater interaction between DES components and lignocellulosic substrates.