Cu@Fe3O4 core-shell nanoparticle-catalyzed oxidative degradation of the antibiotic oxytetracycline in pre-treated landfill leachate

Abstract

Novel Cu@Fe₃O₄ core-shell nanoparticles prepared via a simple reduction method were evaluated for degradation of oxytetracycline (OTC) in pre-treated leachate (L_p-TREA) (leachate treated by conventional methods). Changes in the characteristics of dissolved organic matter (DOM) in the leachate were also investigated to gain a better understanding of the effects of DOM on the performance of Cu@Fe₃O₄. An excellent OTC degradation of >99% was achieved within 30 min under conditions of 1 g/L Cu@Fe₃O₄, 20 mg/L OTC, 20 mM H₂O₂, and initial pH 3.0, which was similar to the efficiency obtained in deionized water (90% even at pH 9.05). Humic acid (HA) and fulvic acid (FA) were completely degraded at initial pH 3, while aromatic protein (AP) with 32.7% of 1-3 kDa constituents were totally transformed to 0.5-1 kDa compounds, and 17% < 0.5 kDa material was degraded. The OTC removal rate decreased gradually as Cu@Fe₃O₄ was repeatedly used, but it was significantly enhanced when Cu@Fe₃O₄ was washed after five uses to remove the organic matter on its surface. The results suggest that Cu@Fe₃O₄ is a promising and effective catalyst for pharmaceutical and personal care product degradation in landfill leachates.

Keywords: Catalyst; Cu@Fe(3)O(4) core-shell; Degradation; Heterogeneous Fenton-like; Leachate.