Ferrate(VI): A green chemistry oxidant for removal of antibiotics in water

Ferrate(VI) (Fe^VIO₄^2-, Fe(VI)) ion is an environmentallyfriendly chemical for water treatment, which can peform a dual function of oxidation and disinfection and forms a non-toxic byproduct, iron(III). This chapter presents an assessment of the potential of ferrate(VI) to oxidize antibiotics (A). The kinetics, stoichiometry, and products and their antibacterial properties are presented. The second-order rate constants, k, of the oxidation reactions at neutral pH were in the range from 5.0 × 10 ^-1 - 1.5 × 10³ M^-1s^-1. At a 10 mg L^-1 K₂FeO₄ dose, half-lives of the oxidation reaction would be in seconds to minutes at a neutral pH. The values of k, and the reaction half-lives, varied with pH. The stoichiometry of the reactions of Fe(VI) with sulfamethoxazole and trimethoprim were 4:1 and 5:1 ([Fe(VI):[A]), respectively. Oxidation products of the reactions were found to be relatively less toxic than parent molecule. The oxidized products of trimethoprim showed no significant antibacterial activity. Examples of efficient removal of antibiotics from the wastewater by Fe(VI) are presented. Overall, ferrate(VI) oxidation could be an effective treatment method for the purification of waters containing antibiotics.