Photoelectrocatalytic degradation of microcystin-LR using a dimensionally stable anode and the assessment of detoxification

Abstract

Microcystins (MCs) pose a great threat to human health due to their toxicity. In this study, photoelectrocatalysis was applied as an effective technology to degrade MCs. The effects of different dimensionally stable anodes and cathodes were evaluated. Detoxification effects were investigated using a luminescence inhibition assay, a micronucleus assay of Vicia faba root tips and a single cell gel electrophoresis assay. The results show that RuO2-TiO2/Ti and stainless steel were the best among the six anodes and four cathodes tested for MCLR degradation. Compared to photodegradation, photocatalysis and electrocatalysis, photoelectrocatalysis obtained the highest efficiency on MCLR degradation, nearly 100% at 254 nm and 5.0 mA/cm2. The degradation kinetics agreed with the Langmuir-Hinshelwood kinetic model. When NaCl was used as an electrolyte, the degradation efficiency of MCLR reached 100% even under 0.002 mol/L, which was much better than that of Na2SO4, Na2HPO4 and NaNO3. The toxicity assays showed that although MCLR was completely degraded, acute toxicity still occurred in the solution at relative luminosities from 0 to 9.37%. However, the micronucleus efficiency and DNA damage of cells returned to normal levels at the end of the reaction. This indicates that genotoxicity and cytotoxicity were eliminated with the degradation of MCLR.