Unique electrochemical system for in situ SO4[rad]− generation and pollutants degradation

Abstract

Sulfate-based electrochemical advanced oxidation is of rising importance for pollutant removal, however, adscititious sulfate has adverse effects on water salinity. A novel electrochemical system which could exploit the existed SO42− for in situ generation of SO4− was successfully constructed with boron doped diamond (BDD) anode and hierarchical 1D Co3O4 nanowire array cathode. The in situ electrochemical electron paramagnetic spectroscopy and titration were used to study the positive correlation between the increase of sulfate radicals (SRs) and the efficient activation of peroxydisulfate (PDS) by hierarchical 1D Co3O4 nanowire array cathode. Electrochemical impedance and X-ray photoelectron spectroscopy revealed that the efficient activation of PDS by the Co3O4 cathode was derived from the excellent electron transport capability of the 1D nanostructure, and the electric field accelerates the reduction of Co(III). The novel hierarchical 1D Co3O4 nanowire array cathode can completely degrade dibutyl phthalate in 45% less time with 38% less energy compared to a traditional graphite cathode without the requirement of extra chemicals. The possible mechanism of anodic PDS accumulation and cathodic SRs generation was firstly revealed, and this advanced electrochemical oxidation system provides a good reference for the in situ sustainable remediation in sulfate-containing water.