ABSTRACT
Our ecosystem is endangered by the increasing demand of resources and emission of pollutants, which requires urgent and innovative solutions such as fuels and chemicals produced from renewable sources and/or via more sustainable technologies. Lignocellulosic biomass is a promising candidate in bio-based energy and chemicals production because of its renewability. However, lignocellulosic biomass is recalcitrant due to its natural complex structure, and therefore, pretreatment is essential to break the interlinks between cellulose, hemicellulose, and lignin for further utilization. Emerging solvents, such as bio-based solvents, ionic liquids, deep eutectic solvents, and supercritical fluids, have been increasingly applied in biomass pretreatment. These emerging solvents are normally claimed as environmentally friendly and able to replace traditional solvents toward a sustainable chemistry, however without a holistic sustainable assessment. An incomprehensive evaluation from single perspective or failing to consider entire life cycles of solvents may lead to the environmental burden shifting. Herein, this chapter summarized typical emerging solvents in the field of biomass pretreatment, discussed criteria for solvents greenness definition, reviewed current comprehensive assessment studies on their selection, and proposed a framework incorporating USEtox model for their sustainability assessment which is a guidance for solvents design and development.
