Selective and Reversible absorption performance of SO2 by bio-based 2-pyrrolidone deep eutectic solvents and mechanism study

In this study, bio-based pyrrolidone (2-Pyr) and low-toxicity tetraethylammonium chloride (TEAC) were selected to prepare inexpensive, low-viscosity deep eutectic solvents (DESs), which is in line with the concept of green and sustainable chemistry and is suitable for industrial production. The highest absorption capacity of TEAC:2-Pyr (1:4) was determined to be 1.03 g SO2 /g DES at 20 °C. Eight absorption–desorption cycling tests were performed, and it was found that the absorption performance of DESs for SO 2 slightly varied. It was also proved that DESs have a certain degree of water resistance and high SO 2 selectivity. Fourier transform infrared spectroscopy and computational chemical analysis showed that the DESs composed of TEAC:2-Pyr formed intermolecular hydrogen bonds, the O atoms in Cl − and 2-Pyr played a role in the absorption of SO 2 , and hydrogen bonds were broken by the addition of SO 2 .