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

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.