Oxidative degradation of the antibiotic oxytetracycline by Cu@Fe3O4 core-shell nanoparticles

Abstract

A core-shell nanostructure composed of zero-valent Cu (core) and Fe3O4 (shell) (Cu@Fe3O4) was prepared by a simple reduction method and was evaluated for the degradation of oxytetracycline (OTC), an antibiotic. The Cu core and the Fe3O4 shell were verified by X-ray diffractometry (XRD) and transmission electron microscopy. The optimal molar ratio of [Cu]/[Fe] (1/1) in Cu@Fe3O4 created an outstanding synergic effect, leading to >99% OTC degradation as well as H2O2 decomposition within 10min at the reaction conditions of 1g/L Cu@Fe3O4, 20mg/L OTC, 20mM H2O2, and pH3.0 (and even at pH9.0). The OTC degradation rate by Cu@Fe3O4 was higher than obtained using single nanoparticle of Cu or Fe3O4. The results of the study using radical scavengers showed that OH is the major reactive oxygen species contributing to the OTC degradation. Finally, good stability, reusability, and magnetic separation were obtained with approximately 97% OTC degradation and no notable change in XRD patterns after the Cu@Fe3O4 catalyst was reused five times. These results demonstrate that Cu@Fe3O4 is a novel prospective candidate for the pharmaceutical and personal care products degradation in the aqueous phase.