Revisiting UV/sulfite exposed to air: A redox process for reductive dechlorination and oxidative mineralization

Ge Song; Pei Su; Qizhan Zhang; Xuechun Wang; Minghua Zhou

doi:10.1016/j.scitotenv.2022.160246

Revisiting UV/sulfite exposed to air: A redox process for reductive dechlorination and oxidative mineralization

Sci Total Environ. 2023 Feb 10;859(Pt 1):160246. doi: 10.1016/j.scitotenv.2022.160246. Epub 2022 Nov 17.

Authors

Ge Song¹, Pei Su¹, Qizhan Zhang¹, Xuechun Wang¹, Minghua Zhou²

Affiliations

¹ Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; Tianjin Advanced Water Treatment Technology International Joint Research Center, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
² Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; Tianjin Advanced Water Treatment Technology International Joint Research Center, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China. Electronic address: zhoumh@nankai.edu.cn.

PMID: 36402334
DOI: 10.1016/j.scitotenv.2022.160246

Abstract

2,4-Dichlorophenol (2,4-DCP) widely exists in many industrial wastewaters and is considered a priority pollutant due to its high toxicity. In this work, we proposed a UV/sulfite process without aeration for high-efficiency dechlorination and enhanced mineralization. The UV/sulfite system significantly improved the removal of 2,4-DCP (93.33 % in 60 min) and dechlorination rate (85.13 % in 60 min) compared with UV alone and sulfite alone, and the synergistic factor was 6.59. The UV/sulfite system without aeration improved the mineralization rate (49.80 %) compared with the nitrogen aeration system. UV/sulfite was a reduction-oxidation coupled process and was more suitable for neutral and alkaline conditions. Reducing species (hydrated electrons and H^•) made 2,4-DCP dechlorinate to form dechlorination products such as p-chlorophenol (4-CP), o-chlorophenol (2-CP), and phenol, which were further mineralized by oxidized species (SO₄^•-). UV/sulfite remained highly efficient in the presence of coexisting ions and under different water quality conditions. This process was also suitable for removing a wide range of chlorinated organic compounds. The UV/sulfite process without aeration can achieve high dechlorination and enhanced mineralization with simple operation and low cost (1.78 $·m^-3 order^-1), which has a broad and cost-effective application prospect in removing refractory halogenated organic pollutants.

Keywords: Dechlorination; Mineralization; Oxidation; Reduction; UV/sulfite.

MeSH terms

Chlorophenols*
Oxidation-Reduction
Phenol
Sulfites
Water Pollutants, Chemical*

Substances

Chlorophenols
Sulfites
Phenol
Water Pollutants, Chemical