Highly dispersed copper oxide-loaded hollow Fe-MFI zeolite for enhanced tetracycline degradation

Framework doped iron materials such as Fe-MFI zeolite is an important heterogeneous Fenton-like catalyst for tetracycline degradation. Introduction of mesopore can enhance the tetracycline degradation performance for hollow Fe-MFI zeolite, however its positive effect is extremely limited ascribed to the essence of active sites of confined framework iron species. In this work, highly dispersed copper oxide on the hollow Fe-MFI zeolite CuO/FeS-1 was synthesized via an impregnation procedure and applied as heterogeneous catalyst for the tetracycline degradation. The synthesized CuO/FeS-1 was characterized by Scanning electron microscopy, Transmission electron microscopy, X-ray diffraction, UV–vis absorption spectrometry, Fourier transform infrared spectroscopy, Nitrogen adsorption-desorption and X-ray photoelectron spectroscopy. At pH = 7.0, CuO/FeS-1 revealed the highest tetracycline degradation rate of 99.6 % at experimental conditions: [TCE] = 30 mg/L, [PMS] = 1.0 g/L, [Catalyst] = 1.0 g/L, 333 K, and the largest degradation rate constant of 1.26 min−1, which was 3.4 folds of FeS-1 zeolite and 1.8 folds of CuO. Electron paramagnetic resonance (EPR) technology disclosed that •OH, SO4•−, 1O2 and •O2− species were all the active species for CuO/FeS-1 zeolite in the tetracycline degradation. Furthermore, possible intermediates in the degradation of tetracycline over CuO/FeS-1 zeolite were identified with liquid chromatography-mass spectrometry (LC-MS).