Absorption of dichloromethane by sulfolane-based non-ionic eutectic solvents: Experimental study and quantum chemical calculations

This study investigates the efficacy of four novel sulfolane-based non-ionic deep eutectic solvents (DESs) for dichloromethane (DCM) absorption. Key physicochemical properties including density, viscosity, and DCM absorption capacity were determined. Notably, Sulfolane-Diethylene glycol butyl ether (SUL-DGBE) (1:3) exhibited optimal fluidity (viscosity = 7.9 mPa & sdot;s at 298.15 K) and superior DCM absorption capacity (Henry's law constant = 10.51 kPa at 298.15 K). Thermal stability and molecular structure of the DESs were characterized via thermogravimetric analysis and infrared spectroscopy. Packed tower experiments demonstrated that SUL-DGBE (1:3) achieved the highest DCM absorption efficiency (93.9 % at 298.15 K) and maintained a robust performance (90.8 % efficiency) after ten regeneration cycles. Quantum chemical (QC) calculations elucidated the molecular mechanism of DCM absorption by the DESs, revealing the contributions of hydrogen bonding and van der Waals interactions. The correlation between electrostatic interactions and hydrogen bond strength was further explored. This work provides valuable insights into the application of DESs for DCM remediation.