Integrating anodic sulfate activation with cathodic HO production/activation to generate the sulfate and hydroxyl radicals for the degradation of emerging organic contaminants.

Conventional electrocatalytic degradation of pollutants involves either cathodic reduction or anodic oxidation process, which caused the low energy utilization efficiency. In this study, we successfully couple the anodic activation of sulfates with the cathodic HO production/activation to boost the generation of sulfate radical (SO) and hydroxyl radical (·OH) for the efficient degradation of emerging contaminants. The electrocatalysis reactor is composed of a modified-graphite-felt (GF) cathode, in-situ prepared by the carbonization of polyaniline (PANI) electrodeposited on a GF substrate, and a boron-doped diamond (BDD) anode. In the presence of sulfates, the electrocatalysis system shows superior activities towards the degradation of pharmaceutical and personal care products (PPCPs), with the optimal performance of completely degrading the representative pollutant carbamazepine (CBZ, 0.2 mg L) within 150 s. Radicals quenching experiments indicated that ·OH and SO act as the main reactive oxygen species for CBZ decomposition. Results from the electron paramagnetic resonance (EPR) and chronoamperometry studies verified that the sulfate ions were oxidized to SOradicals at the anode, while the dissolve oxygen molecules were reduced to HO molecules which were further activated to produce ·OH radicals at the cathode. It was also found that during the catalytic reactions SOradicals could spontaneously convert into peroxydisulfate (PDS) which were subsequently reduced back to SOat the cathodes. The quasi-steady-state concentrations of ·OH and SOwere estimated to be 0.51×10 M and 0.56×10 M, respectively. This study provides insight into the synergistic generation of ·OH/SO from the integrated electrochemical anode oxidation of sulfate and cathode reduction of dissolved oxygen, which indicates a potential practical approach to efficiently degrade the emerging organic water contaminants.