Effects of Halide Anions to Absorb SO2 in Ionic Liquids

Abstract

Ionic liquids with halide anions were prepared and the dependency of halide anions on the SO2 solubility of ILs was investigated. The study shows that the SO2 solubility of ionic liquids lies in the range 1.91 similar to 2.22 SO2/ILs mol ratio. SO2 solubility in ionic liquids with varying halide anions follows the order Br > Cl > I. Theoretical investigation was also conducted at the B3LYP level using the Gaussian 03 program. From the theoretical consideration of the interaction between SO2 and [EMIm]X (where X = Cl, Br, and I), it has been proposed that primary interaction of halide occurs with C-2-H of the imidazolium and S of SO2. Experimental results further shows that the absorption and desorption process of SO2 in ILs was reversible by the three cycles of the absorption at 50 degrees C and desorption at 140 degrees C. The reversibility of SO2 absorption was confirmed by FT-ER studies.