Mechanisms and performance of potassium ferrate in endocrine disrupting chemicals

Abstract

Ferrate(VI) has been found to be a powerful oxidant over a wide pH range and many studies have considered its role as an oxidant in water and wastewater treatment. The research outputs presented in this thesis include an improved procedure for preparing solid potassium ferrate (K2FeO4 of high purity (99%) and high yield (50-70%). In addition, it was discovered that the crystal form of solid potassium ferrate has a tetrahedral structure. Other physical and chemical characteristics of potassium ferrate have also been examined. In order to probe the effect of potassium ferrate on the degradation of endocrine disrupting chemicals (EDCs), the reactions of ferrate(VI) with five EDCs (bisphenol A (BPA), 17a-ethynylestradiol (EE2), estrone (El), 17b-estradiol (E2), estriol (E3)) were studied and an improved second order kinetic model was established to describe them. The kinetic study indicates that the reactivity of HFeO42- is stronger than that of FeO4-. The reaction mechanism of BPA degradation with ferrate(VI) has also been studied using LC/MS/MS and GC/MS/MS methods. The analytical results confirmed a proposed pathway of BPA degradation with ferrate(VI) in an aqueous solution. In addition, ferrate(VI) oxidation of BPA with photocatalytic oxidation has been studied. It was found that the one-step reduction of Fe(VI) to Fe(V) on the TiO2 surface provides an interactive function, which eliminates the recombination of electrons and holes, and hence enhances the efficiency of photocatalytic oxidation and ferrate(VI) oxidation. This research provides information on the preparation of solid potassium ferrate, kinetics of EDCs oxidation with ferrate(VI), and also the reaction mechanism of ferrate associated EDC degradation.