Ferrate(VI) oxidation of endocrine disruptors and antimicrobials in water

Potassium ferrate(VI) (K₂FeO₄) has advantageous properties such as a dual function as an oxidant and disinfectant with a non-toxic byproduct, iron(III), which makes it an environmentally friendly chemical for water treatment. This paper presents an assessment of the potential of ferrate(VI) to oxidize representative endocrine disruptors (EDs) and antimicrobials during water treatment using information about reaction kinetics and products. Selected EDs were bisphenol A (BPA) and 17α-ethynylestradiol (EE2), estrone (E1), 17β-estradiol (E2), and estriol (E3), and sulfonamides and tetracycline were representative pharamaceuticals. The second-order rate constants, k, of the oxidation reactions at neutral pH were in the range from 6.50–11.8 × 10² M⁻¹s⁻¹ and 0.79–15.0 × 10² M⁻¹s⁻¹ for EDs and sulfonamides, respectively. At a 10 mgL⁻¹ K₂FeO₄ dose, half-lives of the oxidation reaction would be in seconds at a neutral pH. The values of k, and the reaction half-lives, varied with pH. Oxidation products from the reaction with BPA and sulamethoxazole (SMX) at molar ratios of ∼5:1 were found to be relatively less toxic. Overall, ferrate(VI) oxidation could be an effective treatment method for the purification of waters containing these particular EDs and antimicrobials.