title: 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.
authors.affiliation: School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin, China.
authors.forename: Xinran
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Applied Chemistry, China Agricultural University , Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Basic Medical Sciences & Center for Cancer Research, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Jer-Yen
authors.initials: JY
authors.lastname: Yang
authors.affiliation: Campus-Wide Mass Spectrometry Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Karl V
authors.initials: KV
authors.lastname: Wood
authors.affiliation: Campus-Wide Mass Spectrometry Center, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Arlene P
authors.initials: AP
authors.lastname: Rothwell
authors.affiliation: School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin, China.
authors.forename: Weiguang
authors.initials: W
authors.lastname: Li
authors.affiliation: Lyles School of Civil Engineering, Purdue University , West Lafayette, Indiana 47907, United States.|Division of Environmental & Ecological Engineering, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Ernest R
authors.initials: ER
authors.lastname: Blatchley Iii
mesh_terms: D002713:Chlorine; D000458:Cyanobacteria / Q000737:chemistry*; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D014881:Water Supply
chemical_list: D002713:Chlorine