New method for the preparation of ferrate(VI) (FeO42−) under acidic conditions

This study, for the first time, describes a novel method for the synthesis of FeVI species under acidic conditions. K2FeO4 was prepared through an oxidation reaction using Ag⁺ and persulfate as raw materials. The structure of K2FeO4 was characterised by Fourier transform-infrared, X-ray diffraction and UV–visible spectroscopies. The results of these characterisations indicated that the synthesised product was indeed K2FeO4. The effects of the concentrations of Fe2(SO4)3, Na2S2O8 and AgNO3, temperature, and recrystallisation temperature on the yield were investigated. The results demonstrated that when [Fe2(SO4)3] = 0.025 mol L–1, [Na2S2O8] = 0.080 mol L–1, [AgNO3] = 0.20 g L–1, the reaction temperature was 55°C, the reaction time was 1 h, and the recrystallisation temperature was 0°C, the yield of K2FeO4 reached 83.4% and the purity could reach 90%. Compared with alkaline methods, this acidic method has several advantages. It reduces environmental hazards, and no precipitation occurs during the experiments. Additionally, it features a short reaction time, a high-purity product and a high conversion rate.