Highly efficient mineralization of phenol through catalytic ozonation using urchin-like CuxCe1Oy-BTC catalysts derived from metal-organic frameworks

Abstract

The efficient mineralization of phenol and its derivatives in wastewater remains a great challenge. In this study, the bimetallic CuCeO₂-BTC was screened from a series of MOFs-derived MCeO₂-BTC (M = La, Cu, Co, Fe, and Mn) catalysts, and the influence of the Cu/Ce ratio on phenol removal by catalytic ozonation was carefully examined. The results indicate that Cu₂Ce₁O_y-BTC was the best among the Cu_xCe₁O_y-BTC (x = 0, 1, 2, and 3) catalysts, with a phenol mineralization efficiency reaching close to 100 % within 200 min, approximately 30.1 % higher than CeO₂-BTC/O₃ and 70.3 % higher than O₃ alone. The order of mineralization efficiency of phenol was Cu₂Ce₁O_y-BTC > Cu₃Ce₁O_y-BTC > Cu₁Ce₁O_y-BTC > CeO₂-BTC. CeO₂-BTC exhibited a broccoli-like morphology, and Cu_xCe₁O_y-BTC (x = 1, 2, and 3) exhibited an urchin-like morphology. Compared with Cu_xCe₁O_y-BTC (x = 0, 1, and 3), Cu₂Ce₁O_y-BTC exhibited a larger specific surface area and pore volume. This characteristic contributed to the availability of more active sites for phenol degradation. The redox ability was greatly enhanced as well. Besides, the surface of Cu₂Ce₁O_y-BTC exhibited a higher concentration of Ce³⁺ species and hydroxyl groups, which facilitated the dissociation of ozone and the generation of active radicals. Based on the results of radical quenching experiments and the intermediates detected by LC-MS, a potential mechanism for phenol degradation in the Cu₂Ce₁O_y-BTC/O₃ system was postulated. This study offers novel perspectives on the advancement of MOFs-derived catalysts for achieving the complete mineralization of phenol in wastewater through catalytic ozonation.