Inactivation of Escherichia coli in Na 2SO 4 electrolyte using boron-doped diamond anode

Abstract

Electrochemical disinfection in chloride-free electrolyte has attracted more and more attention due to advantages of no production of disinfection byproducts (DBPs), and boron-doped diamond (BDD) anode with several unique properties has shown great potential in this field. In this study, inactivation of Escherichia coli ( E. coli) was investigated in Na 2SO 4 electrolyte using BDD anode. Firstly, disinfection tests were carried on at different current density. The inactivation rate of E. coli and also the concentration of hydroxyl radical ( OH) increased with the current density, which indicated the major role of OH in the disinfection process. At 20 mA cm −2 the energy consumption was the lowest to reach an equal inactivation. Moreover, it was found that inactivation rate of E. coli rose with the increasing Na 2SO 4 concentration and they were inactivated more faster in Na 2SO 4 than in NaH 2PO 4 or NaNO 3 electrolyte even in the presence of OH scavenger, which could be attributed to the oxidants produced in the electrolysis of SO 4 2−, such as peroxodisulfate (S 2O 8 2−). And the role of S 2O 8 2− was proved in the disinfection experiments. These results demonstrated that, besides hydroxyl radical and its consecutive products, oxidants produced in SO 4 2− electrolysis at BDD anode played a role in electrochemical disinfection in Na 2SO 4 electrolyte.