Deep eutectic solvents composed of bio-phenol-derived superbase ionic liquids and ethylene glycol for CO 2 capture.

Deep eutectic solvents (DESs) formed by bio-phenol-derived superbase ionic liquids (ILs) and ethylene glycol (EG) exhibit a high CO 2 capacity, up to 1.0 mol CO 2 /mol DESs, which is much better than those of the parent ILs. Surprisingly, mechanism results indicate that CO 2 reacts with EG, but doesn't react with phenolic anions in the solvent, which is different from other DESs formed by superbase ILs and EG. The reaction pathway between CO 2 and DESs used in this work may include two steps. The first step is the acid-base reaction between the phenolic anion and EG, which forms HO-CH 2 -CH 2 -O - , and then CO 2 is attached to the anion HO-CH 2 -CH 2 -O - to form a carbonate species.