Progress on the pre-treatment of lignocellulosic biomass employing ionic liquids

The effective pre-treatment methods are required for the destruction of the complex biomass structure to economically produce high grade fuels and valuable platform chemicals. Ionic liquids have high potential for energy efficient biomass pre-treatment due to their low vapour pressure, emission profile, recyclability and tuneable properties; some ionic liquids can even be prepared from renewable biomass feedstocks. However, a number of issues currently impede the large scale uptake of ionic liquids including their cost of production, detailed understanding the macro, micro and molecular level deconstruction mechanisms which inhibits process optimisation and modelling, and the need for techno-economic astable sessment on large scale trials. So far, laboratory to bench scale IL pre-treatments of various lignocellulosic biomasses were studied by changing various process parameters where the aims were to investigate the biomass dissolution mechanism and understand the pre-treatment performance of ILs. This review outlines current research gaps and potential applications for ionic liquids in the destruction of biomass into its components followed by separation of lignin, hemicellulose and cellulose rich fractions.