The Degradation Of Algal Toxin MCLR And Toxicity Change On The Process Of Photoelectrocatalytic Oxidation

The pollution of algal and its metabolite microcystins cause serious threats to human. The degradation of algal toxin microcystin-LR (MCLR) by photoelectrocatalytic oxidation and detoxification were studied, including anodes selection, reactor design, influence factors, and the toxicity changes during the process of photoelectrocatalytic oxidation were detected by the luminescent acute toxicity test, vicia faba root tip micronucleus method and single-cell gel electrophoresis assay, and the security of the method was discussed.The results showed that the anode materials had great influence on the degradation of MCLR and RuO2/TiO2anode had the best effect with compact surface morphology, favorable crystal form of TiO2, high oxygen evolution potential and voltammetry charge. MCLR removal rate increase form55.9%to79.6%as the increase of the number of electrode form2to6. The immersion type reactor obtained higher current efficiency of MCLR than the external radiation reactor. Besides, TiO2on the electrode surface present obvious photocatalytic effects. The degradation efficiency of photoelectrocatalytic oxidation was higher than that of the sum of photocatalytic oxidation and electrocatalytic oxidation, showing a certain synergetic effect. The best synergetic effect was obtained under optimum match condition of irradiation source and current density, which were irradiation UVC, current density10mA/cm2and irradiation UVA, current density1.0mA/cm2.The removal efficiency in photoelectrocatalytic oxidation decreased along with the increase of the plate distance, which was correlative with electrocatalytic process rather than photocatalytic process; The MCLR removal efficiency decreased with the increase of its initial concentration in photoelectrocatalytic oxidation.Crude MCLR could reduce luminosity of luminescent bacteria, induce Vicia faba root tip micronucleus and DNA damage. During photoelectrocatalytic oxidation process, some acute toxic substances were produced and led to the decrease of relative luminosity of luminescent bacteria from109.6%to zero, but those substances were not genotoxicity, as the treatment progressing, the micronucleus rate and cells DNA damage decreased, the genotoxicity of water samples showed a significantly decline (P<0.05). Photoelectrocatalytic oxidation was effective in reducing genotoxicity.