Heterogeneous sonocatalytic degradation of amoxicillin using ZnO@ for Fe3O4 magnetic nanocomposite: Influential factors, reusability and mechanisms

In this work, ZnO was supported on ferroferric oxide for preparation of a magnetic nanocomposite (ZnO@Fe3O4) and its catalytic activities were examined in the presence of ultrasound (US) irradiation to sonocatalytic degradation of amoxicillin (AMX) during ZnO@Fe3O4/US system. FESEM, EDX, XRD and FTIR techniques were employed for characterization of the as-synthesized catalyst properties. Different experimental variables influencing on the removal of AMX such as solution pH, catalyst loading, initial AMX concentrations and US power were investigated and then optimized. Under optimum experimental conditions, the effect of scavengers, water matrix components and some enhancers on the process performance was examined. A plausible oxidation mechanism was also proposed. In all experiments, AMX removal rates by sonocatalysis process were significantly higher than that of US alone, confirming a synergistic effect between ZnO@Fe3O4 and US irradiation. Under optimized conditions, over 90% of AMX was removed during 120 min reaction. The degradation rate of AMX was enhanced in the presence of enhancers in order of IO4- > S2O82- > H2O2, while it dropped significantly in the presence of anions as Cl- > CO32- > SO42-. Fe leaching from catalyst surface was very minimal (03 mg/L) in the studied pH range. The quenching tests confirmed that center dot OH radicals were the dominant species and responsible in AMX degradation. Cycling tests certificated that the degradation efficiency dropped only by 5% after five successive runs. To conclude, coupling of US and ZnO@Fe3O4 can be satisfactory utilized as an efficient and effective approach to degrade organic matters to remediate the antibiotics-polluted aqueous media. (C) 2018 Elsevier B.V. All rights reserved.