HCl removal and recovery using choline chloride-glycerol deep eutectic solvent in rotor–stator reactor: Molecular mechanism, experimental and modeling studies

Abstract

Efficient removal and recovery of HCl from off-gas are significant for environmental protection and resource utilization. In this work, the absorption process of HCl using choline chloride-glycerol (ChCl-Gly) was studied in three aspects: molecular mechanism, experimental and modeling studies. Firstly, the molecular mechanism of HCl absorption into ChCl-Gly was studied by the σ-profiles, binding models and intermolecular interaction, and it was revealed that the H atom of HCl binds with O and Cl of ChCl-Gly to form hydrogen bonds. Secondly, in view of the absorption characteristics, the process intensification of HCl absorption into ChCl-Gly was proposed by using a rotor–stator reactor (RSR). The influences of the high gravity factor, gas flowrate, ratio of gas flowrate to liquid flowrate and HCl concentration in gas inlet on the removal efficiency of HCl and overall gas-phase volumetric mass-transfer coefficient (KGa) in the removal of HCl by ChCl-Gly in the RSR were explored, and it was found that a larger high-gravity factor led to a better mass transfer effect and higher HCl removal efficiency. In addition, a mass transfer model was built to describe the process of HCl absorption into ChCl-Gly in the RSR, and the model predictions agreed well with the experimental data, and the deviations between experimental and predicted KGa were generally less than ±25 %. Finally, the prospects for industrial applications of HCl removal and recovery using deep eutectic solvents in RSR were discussed.