Efficient absorption of low-concentration SO2 in simulated flue gas by functional deep eutectic solvents based on imidazole and its derivatives

Four thermostable functional deep eutectic solvents (DESs) based on imidazole (Im), 2-methylimidazole, 2-ethylimidazole, and 2-propylimidazole as hydrogen bond acceptor (HBA) and glycerol (Gly) as hydrogen bond donor (HBD) were prepared. All prepared DESs can efficiently capture low-concentration SO2. The SO2 solubility increased with decreasing temperature and increasing SO2 concentration and the available absorption of 2000 ppm SO2 in Im-Gly DES was high, up to 0.634 mol of SO2/mol of Im (0.161 g of SO2/g of DES) with n(Im): n(Gly) = 1: 2 at 40 degrees C. The regeneration experiments showed that the SO2 absorption capacities in Im-Gly DES did not change after 5 absorption/desorption cycles. Furthermore, the absorption mechanism based on H-1 NMR and FTIR analyses indicated that there was an acid-base interaction between SO2 and Im. (c) 2017 Elsevier B.V. All rights reserved.