Low-cost Na₂S-EG-MTPB deep eutectic solvents absorb SO₂ effectively at a high temperature in flue gas

Deep eutectic solvents (DESs) cannot absorb SO₂ at high temperatures, due to the lower solubility of the toxic gas in DESs at high temperatures, limiting their wider uptake in industrial applications. To address this knowledge gap, we added Na₂S to a series of DESs to improve SO₂ adsorption capacity at elevated operating temperatures in this work. The experimental results show that the newly designed Na₂S-EG-MTPB DESs can adsorb SO₂ effectively up to 90 °C. Solid products resulted from the interaction of SO₂ and Na₂S-EG-MTPB DES is mainly elemental sulfur (S₈) and sodium sulfite (Na₂SO₃). DESs can be reused for SO₂ absorption for at least five times by adding additional Na₂S. Therefore, Na₂S-EG-MTPB DESs have great potential as substitutes for existing SO₂ absorbents due to their excellent high temperature resistance, high SO₂ absorption capacity and low cost.