Catalytic ozonation of sulfamethoxazole in water by modified Ca2Fe2O5

Transition metal oxide catalysts are effective for ozone catalytic reactions by promoting free radical generation to degrade organic pollutants. Nevertheless, the development of such catalysts is hampered by low activation efficiency, insufficient active sites, and poor stability of conventional materials. In this study, a perovskite-type transition metal oxide precursor was fabricated by the sol-gel method, subsequently evolving into the Ca ₂ Fe ₂ O ₅ (CFO-700) catalyst through calcination at 700°C, which was then evaluated for the catalytic ozonation of sulfamethoxazole (SMX). The CFO-700/O ₃ system achieved the highest degradation efficiency for SMX. The material was characterized using a series of characterization techniques to determine its key physicochemical properties. The excellent catalytic performance of CFO-700 is attributed to its relatively large specific surface area and pore size, as well as the presence of metal ions in different valence states. These features facilitate the reaction between ozone and low-valence metal ions, generating high-valence metal ions and reactive oxygen species, which accelerates ozone decomposition. Consequently, this promotes the generation of hydroxyl radicals ( ^• OH), enhancing both the degradation efficiency of the pollutant and the overall reaction rate. Collectively, quenching and EPR tests definitively identified ^• OH as the dominant reactive species in the CFO-700/O ₃ system. The material also exhibited high stability over five cycles. This study not only confirms the effectiveness and stability of CFO-700 in catalytic ozonation for SMX degradation but also provides new insights for the application of catalytic ozonation in removing organic pollutants from wastewater.