title: Process optimization for microcystin-LR degradation by Response Surface Methodology and mechanism analysis in gas-liquid hybrid discharge system.
abstract: A gas-liquid hybrid discharge system was applied to microcystin-LR (MC-LR) degradation. MC-LR degradation was completed after 1 min under a pulsed high voltage of 16 kV, gas-liquid interface gap of 10 mm and oxygen flow rate of 160 L/h. The Box-Behnken Design was proposed in Response Surface Methodology to evaluate the influence of pulsed high voltage, electrode distance and oxygen flow rate on MC-LR removal efficiency. Multiple regression analysis, focused on multivariable factors, was employed and a reduced cubic model was developed. The ANOVA analysis shows that the model is significant and the model prediction on MC-LR removal was also validated with experimental data. The optimum conditions for the process are obtained at pulsed voltage of 16 kV, gas-liquid interface gap of 10 mm and oxygen flow rate of 120 L/h with ta removal efficiency of MC-LR of 96.6%. The addition of catalysts (TiO2or Fe2+) in the gas-liquid hybrid discharge system was found to enhance the removal of MC-LR. The intermediates of MC-LR degradation were analyzed by liquid chromatography/mass spectrometry. The degradation pathway proposed envisaged the oxidation of hydroxyl radicals and ozone, and attack of high-energy electrons on the unsaturated double bonds of Adda and Mdha, with MC-LR finally decomposing into small molecular products.
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang, PR China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang, PR China.
authors.forename: Hanyu
authors.initials: H
authors.lastname: Wei
authors.affiliation: College of Electronic Information, Hangzhou Dianzi University, Hangzhou, 310018, PR China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Xin
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang, PR China.
authors.forename: Mingang
authors.initials: M
authors.lastname: Wang
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang, PR China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang, PR China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310018, Zhejiang, PR China. Electronic address: yqcong@hotmail.com.
authors.forename: Yanqing
authors.initials: Y
authors.lastname: Cong
mesh_terms: D000704:Analysis of Variance; D002384:Catalysis; D002853:Chromatography, Liquid / Q000379:methods; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D008387:Marine Toxins; D013058:Mass Spectrometry / Q000379:methods; D052998:Microcystins / Q000737:chemistry*; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry; D012044:Regression Analysis; D014025:Titanium / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D008387:Marine Toxins; D052998:Microcystins; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D017665:Hydroxyl Radical; D010126:Ozone; D006861:Hydrogen Peroxide; D014025:Titanium; D007501:Iron; C057862:cyanoginosin LR
keywords: Catalysts addition; Degradation pathway; Gas–liquid hybrid discharge; Microcystin-LR degradation; Multivariable optimization