Oxidation of Microcystin-LR by Ferrate(VI): Kinetics, Degradation Pathways, and Toxicity Assessments

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• 作者：Wenjun Jiang ; Long Chen ; Sudha Rani Batchu ; Piero R. Gardinali ; Libor Jasa ; Blahoslav Marsalek ; Radek Zboril ; Dionysios D. Dionysiou ; Kevin E. O鈥橲hea ; Virender K. Sharma
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：October 21, 2014
• 年：2014
• 卷：48
• 期：20
• 页码：12164-12172
• 全文大小：353K
• ISSN：1520-5851

文摘

The presence of the potent cyanotoxin, microcystin-LR (MC-LR), in drinking water sources poses a serious risk to public health. The kinetics of the reactivity of ferrate(VI) (Fe^VIO₄^{2鈥?/sup>, Fe(VI)) with MC-LR and model compounds (sorbic acid, sorbic alcohol, and glycine anhydride) are reported over a range of solution pH. The degradation of MC-LR followed second-order kinetics with the bimolecular rate constant (k_MCLR+Fe(VI)) decreasing from 1.3 卤 0.1 脳 102 M鈥? s鈥? at pH 7.5 to 8.1 卤 0.08 M鈥? s鈥? at pH 10.0. The specific rate constants for the individual ferrate species were determined and compared with a number of common chemical oxidants employed for water treatment. Detailed product studies using liquid chromatography鈥搈ass spectrometry/mass spectrometry (LC鈥揗S/MS) indicated the oxidized products (OPs) were primarily the result of hydroxylation of the aromatic ring, double bond of the methyldehydroalanine (Mdha) amino acid residue, and diene functionality. Products studies also indicate fragmentation of the cyclic MC-LR structure occurs under the reaction conditions. The analysis of protein phosphatase (PP1) activity suggested that the degradation byproducts of MC-LR did not possess significant biological toxicity. Fe(VI) was effective for the degradation MC-LR in water containing carbonate ions and fulvic acid (FA) and in lake water samples, but higher Fe(VI) dosages would be needed to completely remove MC-LR in lake water compared to deionized water.}