Unintended polyhalogenated carbazole production during advanced oxidation of coking wastewater

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作   者：

Meng Zhang;  Kunde Lin; 

作者机构：

Xiamen 361102;  College of the Environment and Ecology;  Xiamen University;  Fujian Provincial Key Laboratory for Coast Ecology and Environmental Studies;  China; 

关键词：

Disinfection byproducts;  Halogenated micropollutants;  Polyhalogenated carbazoles;  New pollutants;  Advanced oxidation process; 

期刊名称：

Journal of Hazardous Materials

i s s n：

0304-3894

年卷期：

2024 年 473 卷 Jul.15 期

页   码：

134649.1-134649.10

页   码：

摘   要：

Polyhalogenated carbazoles (PHCZs) are emerging as dioxin-like global pollutants, yet their environmental originsare not fully understood. This study investigates the application of the Fenton process in coking wastewatertreatment, focusing on its dual role in carbazole removal and unintended PHCZ formation. The common halideions (Cl– and Br–) in coking wastewater, especially Br– ions, exerted a notable impact on carbazole removal.Particularly, the influence of Br– ions was more significant, not only enhancing carbazole removal but alsoshaping the congener composition of PHCZ formation. Elevated halide ion concentrations were associated withthe heightened formation of higher halogenated carbazoles. The Fenton reagent dosage ratio was identified as acrucial factor affecting the congener composition of PHCZs and their toxic equivalency value. The coexistingorganic substance (i.e., phenol) in coking wastewater was observed to inhibit PHCZ formation, likely throughcompetitive reactions with carbazole. Intriguingly, ammonium (NH_4~+) facilitated the generation of higher andmixed halogenated carbazoles, possibly due to the generation of nitrogen-containing brominating agents withstronger bromination capacity. This study underscores the importance of a comprehensive assessment, consideringboth substrate removal and potential byproduct formation, when employing the Fenton process for salinewastewater treatment.