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

Abstract

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.

Efficient electrochemical remediation of microcystin-LR in tap water using designer TiO2@carbon electrodes

“…Due to the high toxicity of MC-LR, highly efficient remediation methods have been under development in recent years, with advanced oxidation processes focused on mineralization as major target 15 16 17 18 19 . Electrochemical remediation arose as a interesting alternative with few reported protocols to date which include a catalytic electrodes with Ti, Ir, Pt, BDD 20 21 22 23 .…”

The role of trace N-Oxyl compounds as redox mediator in enhancing antiviral ribavirin elimination in UV/Chlorine process

“…Ecological Structure Activity Relationship (ECOSAR) was used to assess the acute toxicity and chronic toxicity of RBV and its degradation products to fish, daphnid, and green algae, according to their molecular structures [32] .…”

State of the Art of UV/Chlorine Advanced Oxidation Processes: Their Mechanism, Byproducts Formation, Process Variation, and Applications

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