Heterogeneous Fenton behavior of nano nickel zinc ferrite catalysts in the degradation of 4-chlorophenol from water under neutral conditions

An evaluation of heterogeneous Fenton behavior of nano nickel-zinc ferrite catalysts in the Wet Peroxide Oxidation for the degradation of 4-chlorophenol is presented. A series of spinel type NixZn1−xFe2O4 (x = 0.0, 0.25, 0.5, 0.75, 1.0) catalysts were prepared by sol-gel auto combustion method and characterized by X-ray diffraction, Transmission Electron Microscopy, X-ray fluorescence and Fourier Transform Infra-Red spectroscopy. Fenton's reaction was performed over different compositions of nickel zinc ferrite catalysts under neutral conditions and the catalytic activities were studied. The yield of the reaction, based on Gas Chromatographic and Chemical Oxygen Demand (COD) parameters were very high and the experimental results indicated complete degradation of target pollutant with significant reduction of COD with all catalysts within 75 min. Zinc substitution enhanced the catalytic activity of nickel ferrite and the un-substituted ZnFe2O4 degraded the target compound completely within 45 min. Catalysts were found to be reusable and the extent of iron leaching, quantified by Atomic Absorption Spectroscopic studies was negligible after five consecutive cycles indicating the mechanism to be heterogeneous. Phase analysis of catalyst using XRD after the completion of each catalytic cycle confirmed the stability of the catalyst toward the Wet Peroxide Oxidation of 4-chlorophenol.