New insights on the role of NaCl electrolyte for degradation of organic pollutants in the system of electrocatalysis coupled with advanced oxidation processes

• Published in: Journal of environmental chemical engineering 2022-06, Vol.10 (3), p.107414, Article 107414
• Main Authors: Tian, Lei, Zhu, Meng, Zhang, Long-Shuai, Zhou, Li-Juan, Fan, Jie-Ping, Wu, Dai-She, Zou, Jian-Ping
• Format: Article
• Language: English
• Subjects: Advanced oxidation processes; Chlorine-substituted byproducts; Degradation; Electrocatalysis; Organic pollutants; Sodium chloride
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2022.107414

The role of sodium chloride (NaCl) in pollutant degradation in electrocatalysis coupled with advanced oxidation processes (EAOPs) system remains debatable and the formation of toxic chlorine-substituted byproducts during this process has raised growing concern. Herein, the role of NaCl electrolyte for the degradation of p-nitrophenol (4-NP) in the EAOPs (Co3O4/PMS/NaCl) system was identified. Different from the effect of mass transfer, the presence of NaCl electrolyte improved the 4-NP degradation efficiency and the degradation products were affected by the concentrations of peroxymonosulfate (0.01–8 mM) and Cl- (10–100 mM). Besides, different active species (SO4•−, HOCl, or Cl•/ClO•) with different amounts can be produced in the EAOPs systems with three typical PMS concentrations (0.01, 0.032 and 4 mM). Moreover, the formation of chlorine-substituted byproducts can be effectively avoided via adjusting the concentrations of PMS and NaCl to inhibit the formation of Cl•/ClO•. Finally, this EAOPs system was used to degrade the kimchi processing wastewater and 34% of COD and 99% of TN were removed, revealing it has a good practical application. This study illuminates a new role of NaCl as the electrolyte for the degradation of organic pollutants in the EAOPs system for the first time. [Display omitted] •The role of NaCl electrolyte in an EAOPs/PMS system for 4-NP degradation was explored.•4-NP degradation efficiency was markedly improved by NaCl as the electrolyte.•The effects of PMS and NaCl concentrations on the degradation efficiency and degradation mechanism of 4-NP were studied.•By adjusting the concentrations of NaCl and PMS, the formation of toxic chlorine-substituted by-products can be avoided.