Fenton-like degradation of sulfamethazine using Fe3O4/Mn3O4 nanocomposite catalyst: kinetics and catalytic mechanism

The kinetics and catalytic mechanism of sulfamethazine (SMT) degradation using Fe3O4/Mn3O4 nanocomposite as catalysts in heterogeneous Fenton-like process were investigated. The degradation process of SMT conformed to first-order kinetic model. The apparent activation energy (Ea) of the process was calculated to be 40.5 kJ/mol. The reusability and stability of the catalysts were evaluated based on the results of the successive batch experiments. The intermediates were identified and quantified by ion chromatography (IC), high-performance liquid chromatography (HPLC), and gas chromatography–mass spectrometry (GC-MS). The results suggested that the bonds of S–C, N–C, and S–N were broken mainly by ·OH attack to form the organic compounds, which were gradually decomposed into small-molecule organic acids, such as oxalic acid, propionic acid, and formic acid. The possible catalytic mechanism for SMT degradation was tentatively proposed.