Degradation of atrazine in the electrochemical LED-UV/Cl2 system: the role of ˙OH and Cl˙. Issue 9 (13th July 2021)

• Record Type: Journal Article
• Authors: Huang, Ying; Li, Yangyang; Kong, Minghao; Dionysiou, Dionysios D.; Lei, Lecheng
• Is Part Of: Environmental science. Volume 7:Issue 9(2021)
• Page Start: 1630
• Page End: 1642
• Publication Date: 2021-07-13
• Subjects: Water-supply -- Periodicals; Water security -- Periodicals; Water resources development -- Periodicals; Water chemistry -- Periodicals; 553.705
• DOI: 10.1039/d1ew00039j
• Languages: English
• ISSNs: 2053-1400

Abstract

Abstract : EC/Cl2 can be effective for the degradation of contaminants that are at high C 0 and quickly react with Cl˙, while UV-EC/Cl2 can generate ˙OH and reactive chlorine species to efficiently decompose organic contaminants in high-salinity wastewater. Abstract : In this study, electrochemically generated free chlorine (EC/Cl2 ) was activated by UV275nm irradiation to degrade atrazine, a commonly used herbicide, investigating the degradation kinetics and mechanisms. The potential at a RuO2 /IrO2 –Ti anode was optimized as 1.5 V vs. Ag/AgCl through electrochemical measurement methods. The effects of atrazine initial concentration ( C 0 ) on the UV-EC/Cl2 and EC/Cl2 processes were evaluated. The atrazine degradation efficiency under low C 0 conditions is surprisingly distinct from that under high C 0 conditions. Under low C 0 (1 μM) conditions, UV-EC/Cl2 degraded 60% atrazine at 60 min with ˙OH as the dominant species, while EC/Cl2 only removed 6% atrazine within 60 min. Under high C 0 (20 μM) conditions, similar atrazine degradation efficiencies (about 90% within 180 min) were observed both in UV-EC/Cl2 and EC/Cl2 . 50 μM nitrobenzene was used with 20 μM atrazine to conduct competition experiments, which confirmed the significant role of Cl˙ in atrazine degradation in the UV-EC/Cl2 and EC/Cl2 systems. During atrazine degradation by UV-EC/Cl2 and EC/Cl2, transformation products were compared according to high-resolution mass spectra, based on which possible degradation pathways were proposed. Synthetic reverse osmosis concentrate (ROC) was used to mimic the ROC from industrial wastewater and roughly evaluate the performances of UV-EC/Cl2 for the degradation of emerging contaminants, including atrazine, ibuprofen, carbamazepine, and diclofenac. Overall, EC/Cl2 can be effective at optimized anodic potential for the degradation of contaminants that are at high C 0 and quickly react with Cl˙, while UV-EC/Cl2 is able to generate ˙OH and reactive chlorine species to efficiently decompose organic contaminants at varied concentrations.