Mineralization of Ionic Liquids by Catalytic Ozonation\nover ZnO/Ca<sub>2</sub>Fe<sub>2</sub>O<sub>5</sub>

Imidazolyl-based\nionic liquids (ILs) have been widely used in many\nfields, leading to potential environmental problems due to the toxicity\nof ILs. In this work, ZnO/Ca<sub>2</sub>Fe<sub>2</sub>O<sub>5</sub> was prepared and used as an efficient catalyst to mineralize 1-butyl-3-methylimidazolium\nchloride ([BMIM]Cl) ILs using the catalytic ozonation process. [BMIM]Cl\nwas mineralized to CO<sub>2</sub>, H<sub>2</sub>O, NH<sub>4</sub><sup>+</sup>, and Cl<sup>–</sup> in a short time. The mineralization\nefficiency of [BMIM]Cl can reach up to >92% in 120 min with a catalyst\ndosage of 3.3 g/L, an ozone flow rate of 72 mg/min, an initial pH\nof 10.5, and an initial [BMIM]Cl concentration of 175 mg/L. Meanwhile,\nthe degradation pathway of [BMIM]Cl was also proposed. The physical\nand chemical properties of the catalysts were characterized by XRD,\nFTIR, N<sub>2</sub> physical adsorption–desorption profiles,\nTEM, and XPS. The results showed that the ZnO/Ca<sub>2</sub>Fe<sub>2</sub>O<sub>5</sub> catalyst had good stability, and the presence\nof Zn<sup>2+</sup> promoted the decomposition of ozone and the production\nof <sup>•</sup>OH, which increased the degradation efficiency\nof [BMIM]Cl. The catalytic mechanism was also discussed. This research\nshowed a promising way to prepare efficient catalysts for the treatment\nof [BMIM]Cl using the catalytic ozonation process.