title: Ferric ion mediated photodecomposition of aqueous perfluorooctane sulfonate (PFOS) under UV irradiation and its mechanism.
abstract: Perfluorooctane sulfonate (PFOS) recently has received much attention due to its global distribution, environmental persistence and bioaccumulation. The methods for PFOS decomposition are very limited due to its inertness. In this report we first found the photodecomposition of PFOS under UV was greatly accelerated by addition of ferric ions. In the presence of ferric ion (100 μM), PFOS (20 μM) decreased to below the detection limit within 48 h, with the rate constant of 1.67 d(-1), which was 50 times higher than that by direct photolysis (0.033 d(-1)). Besides fluoride and sulfate ions, C2-C8 perfluorocarboxylic acids (PFCAs) were identified as the main intermediates. It was found that addition of PFOS into the FeCl3 aqueous solution led to reduction of UV absorption, and the presence of ferric ion reduced the response of PFOS as analyzed by UPLC-MS/MS, which indicated that PFOS formed a complex with ferric ion. The ESR detection indicated that the electronic state of Fe(3+)-PFOS complex changed during reaction. And the role of oxygen and hydroxyl radical on the defluorination of PFOS was investigated. Accordingly the mechanism for PFOS photodecomposition in the presence of ferric ion was proposed.
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Jin
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: zpy@tsinghua.edu.cn.
authors.forename: Pengyi
authors.initials: P
authors.lastname: Zhang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Shao
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Shiliang
authors.initials: S
authors.lastname: Zhao
mesh_terms: D017738:Alkanesulfonic Acids / Q000737:chemistry* / Q000528:radiation effects*; D002712:Chlorides / Q000737:chemistry*; D004785:Environmental Pollutants / Q000737:chemistry* / Q000528:radiation effects*; D005290:Ferric Compounds / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry; D005466:Fluorocarbons / Q000737:chemistry* / Q000528:radiation effects*; D007501:Iron / Q000737:chemistry; D010782:Photolysis; D013431:Sulfates / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: D017738:Alkanesulfonic Acids; D002712:Chlorides; D004785:Environmental Pollutants; D005290:Ferric Compounds; D005466:Fluorocarbons; D013431:Sulfates; C076994:perfluorooctane sulfonic acid; D007501:Iron; D005459:Fluorides; C024555:ferric chloride
keywords: Ferric ion; Mechanism; Perfluorooctane sulfonate; Photodecomposition