Enhanced heterogeneous photocatalytic perozone degradation of amoxicillin by ZnO modified TiO2 nanocomposites under visible light irradiation

Abstract

This study investigated enhanced photocatalytic activities of ZnO–TiO2 nanocomposite for ozonation and perozone degradation of amoxicillin (AMX) from water. A simple ball milling method was successfully developed for fabrication of ZnO–TiO2. The experiments were conducted in semi-batch mode to study effect of various operational parameters onto AMX degradation by ozonation and perozone under visible light irradiation, including composite ratio, solution pH, photocatalyst dosage, H2O2, and initial AMX concentration. Besides, the AMX degradation kinetic also was fully investigated. Especially, AMX degradation mechanism was deeply discussed using scavenger test of hydroxyl radicals and characteristic data of photocatalyst. The results indicate that optimal composite ratio between ZnO nanoparticles (NPs) and TiO2 was 10. The 10%ZnO–TiO2 catalyst was proved effectively enhancement of AMX degradation due to its highly inhibition ability towards recombination of photogenerated electron-hole pairs and enriched surface hydroxyl groups. The AMX mineralization efficiency by O3/H2O2/10%ZnO–TiO2/Vis maximized (80.0%) which was higher than the sum of those in individual photocatalysis and perozone systems (69.5%). This was due to a synergistic effect between photocatalysis and perozone causing by ZnO–TiO2. The enhanced mechanism of AMX degradation was due to interfacial reactions between O3 or hydroxyl radicals with adsorbed AMX on the ZnO–TiO2's surface, which were caused by photoexcited electrons stored on ZnO–TiO2 and transferred by O3 to produce H2O2, *OH, h +VB, *O2−, and *O3−. The reusability experiment verified a high stability of ZnO–TiO2 through four consecutive cycles with a negligible change in AMX removal. These findings show that ZnO–TiO2 was the fully promising photocatalyst for advanced oxidation processes (AOPs) to remove the antibiotic residue from wastewater.