Electrochemical removal of microcystin-LR from aqueous solution in the presence of natural organic pollutants

Removal of microcystin-LR (MC-LR) from water was evaluated using an electro-oxidation process. Different operating parameters were investigated, including current density, reaction time, anode material and type of supporting electrolyte. The current density and the type of anode material played an important role in the MC-LR degradation efficiency, whereas the type of sodium salts influenced the removal efficiency. The degradation of MC-LR was mainly attributed to direct anodic oxidation. The best operating conditions (98% of MC-LR removal) for MC-LR (initial concentration of 11–13 μg L−1) degradation in solution were obtained at a current density of 38 mA cm−2 for 60 min with a recycling rate of 0.1 L min−1 using a Ti/BDD anode in the presence of 0.2 g L−1 of Na2SO4. The colour caused by the presence of natural organic matter (humic acid) could be diminished by up to 81%. Likewise, MC-LR decomposition exhibited first-order reaction behaviours with a rate coefficient of 0.049 min−1.

► The degradation of MC-LR was mainly attributed to direct anodic oxidation.
► Current density and anode were the main parameters influencing MC-LR oxidation.
► The process applied under the best conditions oxidized 98.4 ± 0.44% of MC-LR.
► Colour induced by humic acid could be optimally diminished by up to 81.2 ± 4.1%.
► The oxidation rate of MC-LR follows the first-order kinetic with a rate of 0.049 min−1.