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

•DESs and their corresponding EG blends were applied in HCl absorption.•Robust absorption of HCl up to 0.881 g/g was successfully achieved in DES/EG-20.•The densified hydrogen bond networks induce the superior HCl absorption.•The HCl capacity is up to 0.700 g/g after ten cycles of absorption and desorption. 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.