Electrochemical degradation of microcystin-LR.

Microcystin-LR present in drinking water sources poses a considerable threat to human health. Conventional oxidation treatment systems, such as photocatalysis and ferrate oxidation, demonstrated the formation of by-products detectable in the treated microcystin-LR solution. This study investigated an electrochemical approach for microcystin-LR oxidation. The oxidation rate of microcystin-LR increased with the current; the oxidation rate was 0.219 min(-1) and the half-life was 2.5 min at an applied current of 100 mA to treat 1.0 mgL(-1) of microcystin-LR solution. These results were almost the same as those obtained from the photocatalytic oxidation of a 0.055 mgL(-1) microcystin-LR solution. The average instantaneous current efficiency of currents from 30 to 150 mA was greatest at 100 mA because both the current and the microcystin-LR concentration limited the oxidation rate. In addition, no by-products were detected by HPLC, which suggests that the microcystin-LR can be decomposed completely by the indirect oxidation of the hydroxyl radicals formed during electrochemical treatment. We demonstrated that the electrochemical oxidation is a promising approach for the complete oxidation of microcystin-LR.