Lingdan Wang, Bing Chen, Gaozu Liao, Jing Wang, Weirui Chen, Xukai Li, Yiming Tang, Xi Wang, Laisheng Li
{"title":"Selective oxidation of ammonium to nitrogen with VUV/UV/Cl⁻ process: efficiency, pathway and mechanism","authors":"Lingdan Wang, Bing Chen, Gaozu Liao, Jing Wang, Weirui Chen, Xukai Li, Yiming Tang, Xi Wang, Laisheng Li","doi":"10.1016/j.jhazmat.2025.138257","DOIUrl":null,"url":null,"abstract":"Conversion of chloride ions (Cl⁻) into reactive chlorine species (RCS) is an effective strategy for ammonium (NH<sub>4</sub>⁺-N) selective oxidation to nitrogen (N<sub>2</sub>) under high salinity conditions. Herein, vacuum ultraviolet (VUV) irradiation was introduced for NH<sub>4</sub>⁺-N removal in simulated recirculating mariculture systems (RMS) water treatment. Complete oxidation of NH<sub>4</sub>⁺-N and 88.3% N<sub>2</sub> selectivity were achieved for VUV/UV/Cl⁻ process. Mechanism analysis revealed that Cl⁻ were effectively converted into RCS under VUV irradiation and chlorine oxide radical (ClO<sup>•</sup>) was the predominant RCS responsible for NH<sub>4</sub><sup>+</sup>-N removal. The pathway of NH<sub>4</sub><sup>+</sup>-N oxidation was proposed as chlorination because chloramine was identified as the main intermediate. Influence factor investigation indicated that Cl⁻ and bicarbonate (HCO<sub>3</sub>⁻) could significantly promote the removal of NH<sub>4</sub><sup>+</sup>-N in VUV/UV/Cl⁻ process due to acceleration of ClO<sup>•</sup> generation. Ultimately, the NH<sub>4</sub><sup>+</sup>-N removal performance of VUV/UV/Cl⁻ process in practical application was also investigated. The results showed that not only NH<sub>4</sub><sup>+</sup>-N in actual seawater or RMS could be converted effectively to N<sub>2</sub>, but also nitrite (NO<sub>2</sub>⁻-N) and partial nitrate (NO<sub>3</sub><sup>⁻</sup>-N) could be removed efficiently by VUV/UV/Cl⁻ process. Hence, the VUV/UV/Cl⁻ process has promising potential in NH<sub>4</sub><sup>+</sup>-N and total nitrogen (TN) removal for RMS water treatment.","PeriodicalId":361,"journal":{"name":"Journal of Hazardous Materials","volume":"5 1","pages":""},"PeriodicalIF":12.2000,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Hazardous Materials","FirstCategoryId":"93","ListUrlMain":"https://doi.org/10.1016/j.jhazmat.2025.138257","RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, ENVIRONMENTAL","Score":null,"Total":0}
Selective oxidation of ammonium to nitrogen with VUV/UV/Cl⁻ process: efficiency, pathway and mechanism
Conversion of chloride ions (Cl⁻) into reactive chlorine species (RCS) is an effective strategy for ammonium (NH4⁺-N) selective oxidation to nitrogen (N2) under high salinity conditions. Herein, vacuum ultraviolet (VUV) irradiation was introduced for NH4⁺-N removal in simulated recirculating mariculture systems (RMS) water treatment. Complete oxidation of NH4⁺-N and 88.3% N2 selectivity were achieved for VUV/UV/Cl⁻ process. Mechanism analysis revealed that Cl⁻ were effectively converted into RCS under VUV irradiation and chlorine oxide radical (ClO•) was the predominant RCS responsible for NH4+-N removal. The pathway of NH4+-N oxidation was proposed as chlorination because chloramine was identified as the main intermediate. Influence factor investigation indicated that Cl⁻ and bicarbonate (HCO3⁻) could significantly promote the removal of NH4+-N in VUV/UV/Cl⁻ process due to acceleration of ClO• generation. Ultimately, the NH4+-N removal performance of VUV/UV/Cl⁻ process in practical application was also investigated. The results showed that not only NH4+-N in actual seawater or RMS could be converted effectively to N2, but also nitrite (NO2⁻-N) and partial nitrate (NO3⁻-N) could be removed efficiently by VUV/UV/Cl⁻ process. Hence, the VUV/UV/Cl⁻ process has promising potential in NH4+-N and total nitrogen (TN) removal for RMS water treatment.
期刊介绍:
The Journal of Hazardous Materials serves as a global platform for promoting cutting-edge research in the field of Environmental Science and Engineering. Our publication features a wide range of articles, including full-length research papers, review articles, and perspectives, with the aim of enhancing our understanding of the dangers and risks associated with various materials concerning public health and the environment. It is important to note that the term "environmental contaminants" refers specifically to substances that pose hazardous effects through contamination, while excluding those that do not have such impacts on the environment or human health. Moreover, we emphasize the distinction between wastes and hazardous materials in order to provide further clarity on the scope of the journal. We have a keen interest in exploring specific compounds and microbial agents that have adverse effects on the environment.