On the dependence of chlorine by-products generated species formation of the electrode material and applied charge during electrochemical water treatment

Chemical water treatment problems such as disinfection by-products formation have urged on the search of better water treatment technologies such as electrochemical water technologies which have been applied successfully in different water/wastewater pollutant removal. However, their wide extension is hindered by some technical problems such as chlorine by-products (CBPs) generated species. Indeed, during electrochemical process, these carcinogenic substances may be formed depending on the electrode material and applied voltage. This review concerns the dependence of CBPs generated species formation of the electrode material and applied charge during electrochemical water treatment. It is concluded that the use of electrodes producing highly reactive species must be more carefully controlled in hygienically and environmentally oriented applications. From this point of view, Pt and boron-doped diamond (BDD) anodes are proved more convenient than other electrodes. Indeed, the great capability of a BDD anode to produce reactive oxygen species and other oxidising species during the electrolysis allows establishing a chlorine-free disinfection process.

Research Highlights
► At [Cl−] < 100 mg L–1, free Cl2(g) can be produced with the risk of DBPs formation.
► Electric field conditions must be optimised to avoid DBPs formation.
► The DBPs formed can be removed by passing through activated carbon.