This minireview describes the strategies for synthesis of fluorinated surfactants potentially non- bioaccumulable. Various strategies have been focused on （Ⅰ） reducing the length of the perfluorocarbon chain, （Ⅱ...This minireview describes the strategies for synthesis of fluorinated surfactants potentially non- bioaccumulable. Various strategies have been focused on （Ⅰ） reducing the length of the perfluorocarbon chain, （Ⅱ） introducing hereto atoms into the fluorocarbon chain, （Ⅲ） introducing branch （herein and after branch means the fluoro-carbon chain section is not straight）. In most cases, the surface tensions versus the surfactant concentrations have been assessed. These above strategies led to various highly fluorinated （perfluorinated or not perfluorinated） surfactants whose chemical changes enabled to obtain novel alternatives to perfluorooctanoic acid （PFOA） and perfluorooctane sulphonate （PFOS）.展开更多
Perfluorooctane sulfonate（PFOS） had wide applications,such as in the electroplating industry,but its use was restricted in 2009 by the Stockholm Convention,due to its environmental persistence and potential hazards....Perfluorooctane sulfonate（PFOS） had wide applications,such as in the electroplating industry,but its use was restricted in 2009 by the Stockholm Convention,due to its environmental persistence and potential hazards.As the most common PFOS alternative,lH,lH,2H,2H-perfluorooctane sulfonic acid（6：2FTS） and its salts have been increasingly used.However,little is known about its photochemical decomposition.This paper reports the ferric ion-induced efficient decomposition and defluorination of 6：2FTS under 254 nm ultraviolet（UV） irradiation;the underlying mechanisms were also investigated.In the presence of 100 ｜imol/L ferric ion and at pH 3.0,the first-order decomposition rate constant of 6：2FTS（10 mg/L） was 1.59/hr,which was 6 times higher than for direct UV photolysis.The effects of the ferric ion concentration and the solution pH on the 6：2FTS photodecomposition were investigated and the optimal reaction conditions were determined.In addition to fluoride and sulfate ions,shorter-chain PFCAs（C2-C7） were detected as major intermediates.The addition of hydrogen peroxide or oxalic acid accelerated the decomposition of 6：2FTS under UV irradiation,but not its defluorination,indicating that hydroxyl radicals can directly react with 6：2FTS but not with the shorter-chain PFCAs.Accordingly,a mechanism for 6：2FTS photochemical decomposition in the presence of ferric ion was proposed,which comprises two reaction pathways.First,hydroxyl radicals can directly attack 6：2FTS,leading to C- C bond cleavage.Alternatively,6：2FTS coordinates with ferric ion to form Fe（III）-6：2FTS complexes,which can undergo ligand-to-metal charge transfer under UV irradiation,causing C-S bond cleavage.展开更多
基金supported by the National Natural Science Foundation of China(No.21102167)the Science and Technology Commission of Shanghai Municipality(No.12DZ1930902)Shanghai Green Chemical Engineering Technology Research Center and the Knowledge Innovation Program of the Chinese Academy of Sciences
文摘This minireview describes the strategies for synthesis of fluorinated surfactants potentially non- bioaccumulable. Various strategies have been focused on （Ⅰ） reducing the length of the perfluorocarbon chain, （Ⅱ） introducing hereto atoms into the fluorocarbon chain, （Ⅲ） introducing branch （herein and after branch means the fluoro-carbon chain section is not straight）. In most cases, the surface tensions versus the surfactant concentrations have been assessed. These above strategies led to various highly fluorinated （perfluorinated or not perfluorinated） surfactants whose chemical changes enabled to obtain novel alternatives to perfluorooctanoic acid （PFOA） and perfluorooctane sulphonate （PFOS）.
基金supported by the National Natural Science Foundation of China(Nos.21221004,21177071)the National Basic Research Program of China(No.2013CB632403)the Collaborative Innovation Center for Regional Environmental Quality
文摘Perfluorooctane sulfonate（PFOS） had wide applications,such as in the electroplating industry,but its use was restricted in 2009 by the Stockholm Convention,due to its environmental persistence and potential hazards.As the most common PFOS alternative,lH,lH,2H,2H-perfluorooctane sulfonic acid（6：2FTS） and its salts have been increasingly used.However,little is known about its photochemical decomposition.This paper reports the ferric ion-induced efficient decomposition and defluorination of 6：2FTS under 254 nm ultraviolet（UV） irradiation;the underlying mechanisms were also investigated.In the presence of 100 ｜imol/L ferric ion and at pH 3.0,the first-order decomposition rate constant of 6：2FTS（10 mg/L） was 1.59/hr,which was 6 times higher than for direct UV photolysis.The effects of the ferric ion concentration and the solution pH on the 6：2FTS photodecomposition were investigated and the optimal reaction conditions were determined.In addition to fluoride and sulfate ions,shorter-chain PFCAs（C2-C7） were detected as major intermediates.The addition of hydrogen peroxide or oxalic acid accelerated the decomposition of 6：2FTS under UV irradiation,but not its defluorination,indicating that hydroxyl radicals can directly react with 6：2FTS but not with the shorter-chain PFCAs.Accordingly,a mechanism for 6：2FTS photochemical decomposition in the presence of ferric ion was proposed,which comprises two reaction pathways.First,hydroxyl radicals can directly attack 6：2FTS,leading to C- C bond cleavage.Alternatively,6：2FTS coordinates with ferric ion to form Fe（III）-6：2FTS complexes,which can undergo ligand-to-metal charge transfer under UV irradiation,causing C-S bond cleavage.
