Department of Chemistry and Biochemistry, Florida International University , 11200 SW Eighth Street, Miami, Florida 33199, United States.
Environ Sci Technol. 2014 Oct 21;48(20):12164-72. doi: 10.1021/es5030355. Epub 2014 Oct 2.
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(VI)O4(2-), 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 (kMCLR+Fe(VI)) decreasing from 1.3 ± 0.1 × 10(2) M(-1) s(-1) at pH 7.5 to 8.1 ± 0.08 M(-1) s(-1) 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-mass spectrometry/mass spectrometry (LC-MS/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.
强毒性的蓝藻毒素微囊藻毒素-LR（MC-LR）存在于饮用水源中，对公众健康构成严重威胁。本研究报道了高铁酸盐（VI）（Fe（VI）O4（2-），Fe（VI））与 MC-LR 及其模型化合物（山梨酸、山梨醇和甘氨酸酐）在不同溶液 pH 下的反应动力学。MC-LR 的降解遵循二级反应动力学，双分子速率常数（kMCLR+Fe（VI））从 pH 7.5 时的 1.3 ± 0.1 × 10(2) M(-1) s(-1)降低到 pH 10.0 时的 8.1 ± 0.08 M(-1) s(-1)。确定了各高铁酸盐物种的比速率常数，并与用于水处理的几种常见化学氧化剂进行了比较。使用液相色谱-质谱/质谱（LC-MS/MS）进行的详细产物研究表明，氧化产物（OPs）主要是芳香环、甲基脱氢丙氨酸（Mdha）氨基酸残基的双键和二烯官能团的羟化的结果。产物研究还表明，在反应条件下，环状 MC-LR 结构发生了断裂。对蛋白磷酸酶（PP1）活性的分析表明，MC-LR 的降解副产物没有显著的生物毒性。Fe（VI）在含有碳酸根离子和富里酸（FA）的水中以及在湖水样品中对 MC-LR 的降解是有效的，但与去离子水相比，需要更高的 Fe（VI）剂量才能完全去除湖水中的 MC-LR。
