Unexpectedly efficient SO₂ capture and conversion to sulfur in novel imidazole-based deep eutectic solvents

Area of Science:

• Green Chemistry
• Materials Science
• Chemical Engineering

Background:

• Sulfur dioxide (SO2) is a major air pollutant requiring effective capture and conversion strategies.
• Deep eutectic solvents (DESs) offer tunable properties for gas absorption applications.
• Sustainable methods for SO2 management are crucial for environmental protection.

Purpose of the Study:

• To develop and demonstrate an innovative strategy for SO2 capture and conversion using novel imidazole-based DESs.
• To evaluate the SO2 loading capacity, reversibility, and conversion efficiency of these DESs.
• To achieve in situ conversion of absorbed SO2 to elemental sulfur without additives.

Main Methods:

• Synthesis of novel imidazole-based deep eutectic solvents.
• Investigation of SO2 absorption capacity and reversibility through cycling experiments.
• In situ conversion of absorbed SO2 to sulfur using hydrogen sulfide (H2S) at room temperature.

Main Results:

• Achieved extremely high SO2 loading capacity, up to 1.39 g g-1.
• Demonstrated excellent reversibility of the DESs over 15 recycles.
• Obtained rapid in situ conversion of absorbed SO2 to elemental sulfur with up to 99% conversion in the presence of H2S at room temperature.

Conclusions:

• Imidazole-based DESs provide a highly effective and sustainable medium for SO2 capture.
• The demonstrated in situ conversion of SO2 to sulfur is efficient and requires no additives.
• This approach offers a promising pathway for SO2 management and resource recovery.