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

• Low-cost Na 2 S-based deep eutectic solvents were synthesized for absorbing low-concentration SO 2 in flue gas. • Na 2 S-based deep eutectic solvents can adsorb SO 2 effectively up at all operating temperatures (30-90 °C). • Effective SO 2 conversion into elemental sulfur (S 8 ) and sodium sulfite (Na 2 SO 3 ) via mediated Na 2 S-DESs Claus process. Deep eutectic solvents (DESs) cannot absorb SO 2 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 Na 2 S to a series of DESs to improve SO 2 adsorption capacity at elevated operating temperatures in this work. The experimental results show that the newly designed Na 2 S-EG-MTPB DESs can adsorb SO 2 effectively up to 90 °C. Solid products resulted from the interaction of SO 2 and Na 2 S-EG-MTPB DES is mainly elemental sulfur (S 8 ) and sodium sulfite (Na 2 SO 3 ). DESs can be reused for SO 2 absorption for at least five times by adding additional Na 2 S. Therefore, Na 2 S-EG-MTPB DESs have great potential as substitutes for existing SO 2 absorbents due to their excellent high temperature resistance, high SO 2 absorption capacity and low cost.