Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5117209 | Journal of Environmental Management | 2016 | 7 Pages |
â¢RSM was used for MC-LR removal in a discharge system.â¢Addition of TiO2 or Fe2+ in the discharge system enhanced the removal of MC-LR.â¢Small molecular by-products of MC-LR were produced in the discharge.â¢Proposed degradation pathway suggests double bonds in Adda or Mdha chain broken.
A gas-liquid hybrid discharge system was applied to microcystin-LR (MC-LR) degradation. MC-LR degradation was completed after 1Â min under a pulsed high voltage of 16Â kV, gas-liquid interface gap of 10Â mm and oxygen flow rate of 160Â 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 16Â kV, gas-liquid interface gap of 10Â mm and oxygen flow rate of 120Â L/h with ta removal efficiency of MC-LR of 96.6%. The addition of catalysts (TiO2 or 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.
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