Effective Absorption of 1,2-Dichloroethane Using Low-Viscosity Deep Eutectic Solvents

Deep eutectic solvents (DESs) as relatively novel green solvents have potential spread wide applications in separation processes, especially for acid gases and volatile organic compounds (VOCs) absorption. However, the high viscosity of typical DESs can decrease the mass transfer rate and increase energy consumption for pumping, thereby limiting their overall efficiency and feasibility in industrial applications. In this work, the efficient absorption of 1,2-dichloroethane (DCE) was intensified by designing a series of low-viscosity DESs, and the absorption performance, separation mechanism, and conceptual industrial process simulation were systematically investigated. The results showed that 3,4-DMOET:ButA with molar ratio of 1:2 was chosen as the suitable absorbent for DCE due to its maximum saturated absorption capacity (2746 mg/g at 20 °C, atmospheric pressure, and saturated content of DCE in the feed gas) and minimum viscosity property (26.51 mPa·s at 20 °C). The absorption mechanism was investigated by ¹H NMR, FT-IR and quantum chemical (QC) calculations, indicating that the absorption was a physical process. The weak interaction analysis results illustrated that both HBD and HBA play an important role in the separation. Specifically, C–H···π and C–H···Cl are the main contributors to the HBA–DCE interaction, while C–H···O HB and vdW interactions played a dominant role in the HBD–DCE interaction. According to the process simulation results of DES absorbing DCE, it can be seen that DES exhibits a high DCE removal performance. The process intensification strategy may be directly extended to absorb other VOCs.