Chlorine/UV Process for Decomposition and Detoxification of Microcystin-LR

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• 作者：Xinran Zhang ; Jing Li ; Jer-Yen Yang ; Karl V. Wood ; Arlene P. Rothwell ; Weiguang Li ; Ernest R. Blatchley III
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：July 19, 2016
• 年：2016
• 卷：50
• 期：14
• 页码：7671-7678
• 全文大小：437K
• 年卷期：0
• ISSN：1520-5851

文摘

Microcystin-LR (MC-LR) is a potent hepatotoxin that is often associated with blooms of cyanobacteria. Experiments were conducted to evaluate the efficiency of the chlorine/UV process for MC-LR decomposition and detoxification. Chlorinated MC-LR was observed to be more photoactive than MC-LR. LC/MS analyses confirmed that the arginine moiety represented an important reaction site within the MC-LR molecule for conditions of chlorination below the chlorine demand of the molecule. Prechlorination activated MC-LR toward UV₂₅₄ exposure by increasing the product of the molar absorption coefficient and the quantum yield of chloro-MC-LR, relative to the unchlorinated molecule. This mechanism of decay is fundamentally different than the conventional view of chlorine/UV as an advanced oxidation process. A toxicity assay based on human liver cells indicated MC-LR degradation byproducts in the chlorine/UV process possessed less cytotoxicity than those that resulted from chlorination or UV₂₅₄ irradiation applied separately. MC-LR decomposition and detoxification in this combined process were more effective at pH 8.5 than at pH 7.5 or 6.5. These results suggest that the chlorine/UV process could represent an effective strategy for control of microcystins and their associated toxicity in drinking water supplies.