Deep eutectic solvents as promising pretreatment agents for sustainable lignocellulosic biorefineries: A review

Increasing reliance on non-renewable fuels has shifted research attention to environmentally friendly and sus-tainable energy sources. The inherently recalcitrant nature of lignocellulosic biomass (LCB) makes downstream processing of the bioprocess challenging. Deep eutectic solvents (DESs) are popular and inexpensive green liquids found effective for LCB valorisation. DESs have negligible vapor-pressure and are non-flammable, recyclable, cost-economic, and thermochemically stable. This review provides a detailed overview on the DESs types, properties and their role in effective delignification and enzymatic digestibility of polysaccharides for cost-effective conversion of LCB into biofuels and bioproducts. The conglomeration of DESs with assistive pretreat-ment techniques can augment the process of biomass deconstruction. The current challenges in upscaling the DESs-based pretreatment technology up to commercial scale is summarized, with possible solutions and future directions. These insights would fill the knowledge-gaps to towards development of lignocellulosic biorefineries and to address the global energy crisis and environment issues.

Automated summary

This review provides a detailed overview of the role of deep eutectic solvents (DESs) in the conversion of lignocellulosic biomass into biofuels and bioproducts, as well as their combination with assistive pretreatment techniques. It also summarizes the challenges and future directions in scaling up DES-based pretreatment technology to commercial scale.