Ionic liquid-assisted bioconversion of lignocellulosic biomass for the development of value-added products

Lignocellulosic biomass is the most abundant inexpensive renewable source for obtaining biofuels and bioproducts. One of the greatest problems faced in valorizing biomass arises from the recalcitrance of the lignin–carbohydrate complex resulting in inefficient conversion into value-added products. Some ionic liquids (ILs) have proved effective solvents for deconstructing lignocellulosic biomass, however. In fact, ILs provide uniquely “green” alternatives to hazardous conventional volatile organic solvents. Progress in IL-based pretreatment methods can lead to increased productivity in the conversion of lignocellulosic materials. This review discusses the potential of the most prominent types of ILs for lignocellulosic biomass conversion and the influence of their cation–anion combination on their physicochemical properties. Also, it describes existing approaches to the dissolution and fractionation of the three major components of lignocellulosic biomass with ILs and classifies them according to target. Finally, the optimum operating conditions for the dissolution process are commented on and the challenges to be overcome in using ILs for biomass pretreatment and processing on an industrial level are considered, especially as regards synthesis costs and economic hurdles. The high potential of ILs for this purpose is expected to boost research into the topic and lead to substantial industrial progress in this area.