title: High-valent iron (Fe(VI), Fe(V), and Fe(IV)) species in water: characterization and oxidative transformation of estrogenic hormones.
abstract: This paper presents solid state synthesis and characterization of tetra-oxy iron(iv) and iron(v) species in their salt forms (Na4FeO4-Fe(IV) and K3FeO4-Fe(V)). Stability of the synthesized salts, commonly called ferrates, in water was determined by applying the (57)Fe Mössbauer spectroscopy technique. Within 2 s in water, Fe(IV) converted into Fe(III) while Fe(V) transformed into Fe(VI) and Fe(III) at pH = 8.2. Comparatively, Fe(VI) (bought as K2FeO4) remained stable in aqueous solution during the short time period. The oxidative removal efficiency of the high-valent iron species was then tested against five environmentally important estrogenic hormones (estron (E1), 17-β-estradiol (E2), estriol (E3), 17-α-ethinylestradiol (EE2), and diethylstibestrol (DES)) in effluent water of a wastewater treatment plant. Three dosages of iron species (1, 10, and 100 mg L(-1)) were applied to the effluent water. An increase in the concentration of dosages enhanced the removal of estrogens. Both Fe(V) and Fe(VI) were effective in degrading estrogens, but Fe(IV) showed limited oxidation capacity to transform estrogens. The oxidized products of the estrogens were analyzed using Raman spectroscopy and high-performance liquid chromatography-mass spectrometry (HPLC-MS) techniques. Results demonstrated the transformation of estrogens into low molecular weight oxygenated compounds such as quinone-like and opened-aromatic ring species. A detailed study on E1 by using excess Fe(VI) showed the mineralization of the parent compound. The results demonstrate great potential of high-valent iron species in the degradation of endocrine disruptor chemicals like estrogens with several superior aspects including fast reactions, complete degradation and/or formation of benign organic species, and environmentally-acceptable iron oxide by-products.
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Departments of Physical Chemistry and Experimental Physics, Faculty of Science, Palacky University in Olomouc, Šlechtitelů 27, 783 71 Olomouc, Czech Republic. radek.zboril@upol.cz.
authors.forename: Karolína
authors.initials: K
authors.lastname: MachalováŠišková
authors.forename: Daniel
authors.initials: D
authors.lastname: Jančula
authors.forename: Bohuslav
authors.initials: B
authors.lastname: Drahoš
authors.forename: Libor
authors.initials: L
authors.lastname: Machala
authors.forename: Pavel
authors.initials: P
authors.lastname: Babica
authors.forename: Paula Godoy
authors.initials: PG
authors.lastname: Alonso
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Trávníček
authors.forename: Jiří
authors.initials: J
authors.lastname: Tuček
authors.forename: Blahoslav
authors.initials: B
authors.lastname: Maršálek
authors.forename: Virender K
authors.initials: VK
authors.lastname: Sharma
authors.forename: Radek
authors.initials: R
authors.lastname: Zbořil
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D010084:Oxidation-Reduction; D062065:Wastewater; D014867:Water / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D007501:Iron; D062065:Wastewater; D014867:Water; C017311:ferrate ion; C000499:ferric oxide