Ionic liquids, deep eutectic solvents and liquid polymers as green solvents in carbon capture technologies: a review

Global warming is a critical issue resulting partly from increasing carbon dioxide emissions. Technologies have been developed to capture carbon dioxide followed by storage or utilization, yet techniques are limited by the use of toxic solvents and the generation of harmful by-products. Research in green chemistry has designed green solvents which are non-toxic, efficient and environmentally friendly. Here we review green solvents employed for carbon capture, with emphasis on ionic liquids, deep eutectic solvents and liquid polymers. Solvent performance depends on temperature, density and viscosity. Deep eutectic solvents appear as the most advanced solvents with capacities reaching up to 4.292 g CO 2 per g of solvent. Ionic liquids have shown CO 2 uptakes of 4.72 mol of CO 2 /mol of solvent, but are less efficient on average. Liquid polymers display capacities of up to 1.357 mol of CO 2 /mol of solvent.