Photocatalytic properties of nanosized zinc ferrite and zinc chromite

A simple one-step synthesis of developed surface zinc ferrite is proposed (S _BET = 453.1 m² g⁻¹). The formation of zinc ferrite, zinc chromite (S _BET = 53.6 m² g⁻¹), and mixed zinc ferrite-chromite (S _BET = 37.4 m² g⁻¹) structures is studied. The resulting materials are analysed using x-ray phase and x-ray fluorescence analysis, IR spectrometry, electron microscopy, TGA and BET method. Single-phase sample formation mechanism is proposed, which includes transition element cation chelate complex formation stage in the presence of citric acid and subsequent thermal decomposition of the complexes formed. The synthesised materials exhibited photocatalytic activity in the decomposition of an organic dye under the action of hydrogen peroxide. The highest catalytic activity is demonstrated by zinc ferrite in acidic medium; the calculated reaction rate constant is 0.010 min⁻¹ for ZnFe₂O₄, 0.008 min⁻¹ for ZnFeCrO₄, 0.007 min⁻¹ for ZnCr₂O₄. The results can be applied to obtain materials suitable for wastewater treatment processes at industrial enterprises where organic dyes are used in production cycles. (paper)