Effective absorption of dichloromethane using deep eutectic solvents.

Area of Science:

• Environmental Chemistry
• Materials Science

Background:

• Chlorinated volatile organic compounds (VOCs), particularly dichloromethane (DCM), are hazardous atmospheric pollutants due to extensive use and volatility.
• Efficient DCM treatment is crucial for environmental protection and human health.

Purpose of the Study:

• To investigate the capture of DCM using deep eutectic solvents (DESs) with varying hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs).
• To determine the optimal DES composition for maximum DCM absorption capacity.

Main Methods:

• Systematic investigation of DCM capture using various DESs.
• Characterization of DCM absorption capacity at different temperatures and partial pressures.
• Exploration of the microscopic absorption mechanism using 1HNMR, FT-IR, and quantum chemistry calculations.

Main Results:

• Tetrabutylphosphonium chloride: levulinic acid ([P4444][Cl]-LEV) exhibited the highest DCM absorption capacity.
• A capacity of 899 mg DCM/g DES (5.58 mol DCM/mol DES) was achieved with [P4444][Cl]-LEV (1:2) at 30 °C and 0.3 bar DCM partial pressure.
• Absorption was identified as a physical process, with interaction energy and hydrogen bonding significantly influencing DCM uptake.

Conclusions:

• DESs offer an effective strategy for DCM capture.
• [P4444][Cl]-LEV demonstrates superior performance, highlighting the importance of HBA and HBD selection.
• Understanding the physical absorption mechanism and interaction energies can guide the development of advanced DCM capture materials.