Novel Ether-Functionalized Pyridinium Chloride Ionic Liquids for Efficient SO2 Capture

Sulfur dioxide (SO2) emitted from the combustion of fossil flues is a major atmospheric pollutant that seriously threatens the environment and human health. The traditional methods for the removal and recovery of SO2 are irreversible and can result in secondary pollution or suffer from solvent loss. Therefore, it is urgent to explore new absorbents for the reversible, efficient, and environment-friendly capture of SO2. Ionic liquids (ILs) exhibit excellent performance for SO2 capture because of their unique physicochemical properties. To improve the absorption capacities of ILs for SO2, a series of novel ether-functionalized pyridinium chloride ILs ([EnPy]Cl, n = 24) were designed and synthesized. The physiochemical properties of these ILs and their SO2 absorption performance under different conditions were investigated. In addition, the SO2/CO2 selectivities and reusabilities of the ILs and the absorption mechanism between SO2 and [EnPy]Cl (n = 24) were studied. It was found that 1-[2-(2-methoxyethoxy)ethyl] pyridinium chloride showed a relatively high absorption capacity of up to 1.155 (g of SO2).(g of IL)(-1) at 20 degrees C and 0.1 MPa. The SO2 absorption capacities of the studied ILs remained steady in absorptiondesorption cycles, implying that [EnPy]Cl (n = 24) could be promising candidates for SO2 capture.