Highly efficient absorption of HCl in deep eutectic solvents and their corresponding ethylene glycol blends

Effective separation of by-product HCl is of great importance for its recovery and high-value utilization. Herein, a novel strategy for highly efficient and reversible absorption of HCl using deep eutectic solvents (DESs) and their corresponding ethylene glycol blends (DES/EG blends) was reported. HCl uptakes (up to 0.881 g/g) higher than that of water (0.67 g/g) were achieved. The density, viscosity, thermal decomposition temperatures, melting points and the HCl uptakes (0–1.0 bar, 293.2–328.2 K) of DESs or DES/EG blends were systematically determined. Almost pure HCl (greater than99.5 %) could be easily stripped out at elevated temperature and reduced pressure. Spectroscopic characterizations paired with theoretical calculations were applied to characterize the interaction mechanism of HCl in DESs or DES/EG blends. It is the densified hydrogen bond networks in DESs or DES/EG blends that can lower the energy level of systems and induce the superior absorption of HCl. This work provides novel insights into high-performance DESs or DES/EG blends for the absorption of HCl.