High-valent iron-based oxidants to treat perfluorooctanesulfonate and perfluorooctanoic acid in water

• Published in: Environmental chemistry letters 2014-09, Vol.12 (3), p.413-417
• Main Authors: Yates, Brian J, Darlington, Ramona, Zboril, Radek, Sharma, Virender K
• Format: Article
• Language: English
• Subjects: Acids; Analytical Chemistry; Anions; Aquatic environment; Bioaccumulation; byproducts; Contaminants; Drinking water; Earth and Environmental Science; Ecotoxicology; Effluent treatment; effluents; Environment; Environmental Chemistry; Geochemistry; human health; Industrial products; Iron; Liquid chromatography; Mass spectrometry; Original Paper; oxidants; Oxidation; Oxidizing agents; perfluorocarbons; Perfluorooctanoic acid; Pollution; remediation; wastewater; Wastewater treatment; Water; Water pollution
• ISSN: 1610-3653; 1610-3661
• DOI: 10.1007/s10311-014-0463-5

Perfluoroalkyl and polyfluoroalkyl substances are occurring in consumer and industrial products. They have been found globally in the aquatic environment including drinking water sources and treated wastewater effluents, which has raised concern of potential human health effects because these substances may be bioaccumulative and extremely persistent. The saturated carbon–fluorine bonds of the substances make them resistant to degradation by physical, chemical, and biological processes. There is therefore a need for advanced remediation methods. Iron-based methods involving high-valent compounds are appealing to degrade these substances due to their high oxidation potentials and capability to generate environmentally friendly by-products. This article presents for the first time the oxidation ability of tetraoxy anions of iron(V) (FeⱽO₄ ³⁻, Fe(V)), and iron(IV) (FeᴵⱽO₄ ⁴⁻, Fe(IV)), commonly called ferrates, in neutral and alkaline solutions. Solid compounds of Fe(V) (K₃FeO₄) and Fe(IV) (Na₄FeO₄) were added directly into buffered solution containing perfluorooctansulfonate and perfluorooctanoic acid at pH 7.0 and 9.0, and mixed solutions were subjected to analysis for remaining fluoro compounds after 5 days. The analysis was performed by liquid chromatography–mass spectrometry/mass spectrometry technique. Fe(IV) showed the highest ability to oxidize the studied contaminants; the maximum removals were 34 % for perfluorooctansulfonate and 23 % for perfluorooctanoic acid. Both Fe(V) and Fe(IV) had slightly higher tendency to oxidize contaminants at alkaline pH than at neutral pH. Results were described by invoking reactions involved in oxidation of perfluorooctansulfonate and perfluorooctanoic acid by ferrates in aqueous solution. The results demonstrated potentials of Fe(V) and Fe(IV) to degrade perfluoroalkyl substances in contaminated water.