Nanostructured magnetic inverse spinel Ni-Zn ferrite as environmental friendly visible light driven photo-degradation of levofloxacin

Spinel ferrites with a compatible electronic band structure are always excellent candidates for photo-catalytic environmental detoxification employing visible light and solar energy. However, the potential is not harnessed to its fullest owing to unnerving charge carrier recombination. In this work, we report the synthesis of Ni1-xZnxFe2O4 (x = 0, 0.1, 0.3, & 0.5) mixed spinel ferrites via combustion route. As prepared samples were characterized for phase identification using X-ray diffraction (XRD) and Reitveld refined pattern confirms the formation of single phased cubic structure with a nano-metric crystallite size. The homogeneous distribution of grains and particles is evidenced by shape and size morphological studies. Raman spectroscopy reveals the presence of motion of oxygen in tetrahedral and octahedral voids. The dc electrical resistivity measured using the two probe method is found to be in the range of 10(7) to 10(8) Omega-cm. The optical band gap measured for all photo-catalysts resides at 2.11-2.53 eV. The ferrite photocatalyst exhibits high visible absorption, superior charge transfer capacity, and highly suppressed recombination as suggested by electrochemical impedance spectroscopy and photoluminescence results. The change in band structure with variable Zn content was monitored by shifting of conduction and valence bands. The photo-catalyst Ni0.7Zn0.3Fe2O4 (N2) exhibited 96.8% levofloxacin (LEV) degradation in 90 min of visible light exposure. The effect of parameters such as pH, catalyst dosage, electrolytes and water matrix was analysed in detail. The photo-catalytic degradation rate was enhanced in the presence of persulfate and H2O2. Furthermore, the high magnetic character of the catalysts aids in their retrieval post utilization in catalysis. In terms of band structure analysis, role of dopants, metal redox, and scavenging studies, a suitable photo-catalytic process was proposed. Degradation intermediates discovered by liquid chromatography-mass spectrometry analysis were also recommended as a pathway of degradation. These findings open up exciting possibilities for developing novel solar active photo-catalytic systems based on spinel ferrites for efficient environmental cleanup. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

This study successfully synthesized Ni-Zn-Fe mixed spinel ferrite photocatalysts via combustion route, demonstrating high photocatalytic performance and stable photodegradation effects. The degradation rate was further enhanced by analyzing parameters and introducing additives in experiments.