Enhanced chlorine enrichment via electron-deficient centers of Co(III) for efficient electrochlorination and ammonia removal

Abstract

Subject to the sluggish enrichment kinetics of Cl- at anodic active sites, the chlorine evolution reaction (CER) activity and selectivity of current anodes are dissatisfactory for the treatment of ammonia-containing wastewater. In this study, antimony and stannum with strong electronegativity are synchronously introduced into cobaltosic oxide (Sb2O5-Co3O4/Sn) to induce the construction of Co(III) sites with robust electron-deficient centers. The formation of such electron-deficient centers of Co(III) strengthens the enrichment of Cl- and broadened the potential difference of chlorine/oxygen evolution, thereby promoting the CER activity and selectivity at low Cl- concentration. 50.0 mg/L of ammonia-nitrogen can be mineralized into nitrogen within 90 min in the EC system assembled with Sb2O5-Co3O4/Sn anode, which is superior to that of the commercial dimensionally stable anode. Finally, the system shows exceptional feasibility of practical ammonia-containing wastewater purification. This study opens novel avenues to design anodes for highly selective CER and efficient treatment of ammonia-contaminated effluents.