Absorption of SO2 in Furoate Ionic Liquids/PEG200 Mixtures and Thermodynamic Analysis

Carboxylate ionic liquid (IL) and polyethylene glycol 200 (PEG200) mixtures are suitable for the absorption of acidic SO 2 because of their unique properties. In the present work, tetraethylammonium furoate ([N 2222 ][FA]) and choline furoate ([Ch][FA]) were blended with PEG200 to form 40 wt % ILs/PEG200 mixtures as SO 2 absorbents. The solubilities of SO 2 in these two ILs/PEG200 mixtures were measured at T = (303.15, 313.15, 323.15, and 333.15) K and pressure up to 1.2 bar. [N 2222 ][FA]/PEG200 demonstrated the high SO 2 absorption capacity of 7.224 mol per kg absorbent at 303.15 K and 1.0 bar. The chemisorption mechanism of SO 2 by mixture was studied by Fourier transform infrared and nuclear magnetic resonance spectra, and the influence of cations on the SO 2 absorption capacity was analyzed. Furthermore, the reaction equilibrium thermodynamic model was used to correlate the experimental data, and Henry’s law constant ( H ), reaction equilibrium constant ( K 0 ), and thermodynamic properties (Δ r G m 0, Δ r H m 0, and Δ r S m 0 ) were derived. The absorption enthalpies of the two binary mixtures are −46.39 and −23.07 kJ·mol –1 for the two mixtures, respectively. Considering the low cost, biodegradability of the materials, high capacity, and low absorption enthalpy, the [N 2222 ][FA]/PEG200 mixture was regarded to be an attractive and promising alternative to pure ILs and ordinary solvent as a desulfurizer.