Efficient removal of the antibiotic Cefixime on MgZnO under solar light: kinetic and mechanism studies.

The heterogeneous photocatalysis is known to provide significant degradation and mineralization of emerging contaminants including antibiotics. For this, nanosized MgZnO (MZO) was prepared by nitrate route to be used as photocatalyst. The single-phase was confirmed by X-ray diffraction with a crystallite size of 33 nm. The morphology was visualized by scanning electron microscope/energy-dispersive X-ray analysis. The physicochemical properties were studied by the FTIR, XPS, and optical analyses. The diffuse reflectance gives a direct forbidden band of 3.26 eV. The electrochemical characterization showed an n-type semiconductor with a flat band of - 0.56 V. The photodegradation of Cefixime (CFX) was carried out under solar light; the operating parameters such as the catalyst dose, solution pH, and initial CFX concentration (C) were optimized. The best performance occurs at neutral pH ~ 6 within 4 h with an abatement of 94% for an initial CFX concentration of 5 mg/L and MZO dose of 0.75 g/L. The photodegradation follows a first-order kinetic with an apparent rate constant of 0.012 min. The effects of scavenging agents indicated the dominant role of hydroxyl OH followed by the holes (h). The results showed the potentiality of MZO as an environmentally friendly photocatalyst for CFX photodegradation.