Bromide accelerates oxidation of selenite by unactivated peroxymonosulfate: PH-dependent kinetics, mechanism and pathways

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research Pub Date : 2025-01-11 DOI:10.1016/j.watres.2025.123123

Jinrong Lv , GuiFa Long , Ting Xie , Zhangyan Li , Diangui Huang , Xuecai Tan , Bernard A. Goodman , Zhimin Qiang , Shaogang Liu , Huiyu Dong

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Abstract

Selenium (Se) is an essential trace element that is toxic to humans in a relatively small excess. In natural waters it occurs mainly in inorganic form as Se(IV) and Se(VI) oxyanions with the former being more toxic at high levels. With the increasing use of advanced oxidation processes in drinking water treatment, the oxidation of Se(IV) with unactivated peroxymonosulfate (PMS) has been investigated, but the role of bromide (Br⁻) on the oxidation of Se(IV) during reaction with unactivated PMS remains unknown. In the present work, several influencing factors on this reaction are reported, including PMS and Se(IV) concentrations, pH, Br⁻, and natural organic matter (NOM), on the oxidation of Se(IV), as well as the influence of different water matrices. Results show that the second-order rate constant for reaction of Se(IV) with PMS increases with increasing pH (5.0–10.0) from 0.02 to 0.33 M⁻¹ s⁻¹, and that Se(IV) oxidation occurs mainly via a direct oxidation pathway. This increases with increasing initial concentrations of PMS and Se(IV), but is inhibited by the presence of NOM. However, the presence of Br⁻ significantly enhances Se(IV) oxidation at circumneutral pH, but has negligible effect in alkaline conditions. It is proposed that Se(IV) oxidation by PMS involves formation of a hypobromous acid/hypobromite (HOBr/OBr⁻) intermediate in the presence of Br⁻, and its formation is supported by DFT calculations. Based on these results, a kinetics model for Se(VI) formation in bromide-containing water has been developed. Also, compared to the Br⁻/NOM/PMS system, the presence of Se(IV) inhibited the formation of brominated disinfection by-products (i.e., bromform and tribromoacetic acid). Overall, these results help improve our understanding of the behavior of selenium in water containing Br⁻ during a common oxidative treatment process.

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溴化物加速亚硒酸盐被未激活的过氧单硫酸盐氧化：ph依赖性动力学，机制和途径

硒（Se）是一种必需的微量元素，相对少量过量对人体是有毒的。在自然水体中，它主要以无机形式存在，如硒（IV）和硒（VI）氧离子，前者在高水平时毒性更大。随着高级氧化工艺在饮用水处理中的应用越来越多，人们研究了未活化过氧单硫酸盐（PMS）对Se（IV）的氧化作用，但溴化物（Br−）在与未活化过氧单硫酸盐（PMS）反应中对Se（IV）的氧化作用尚不清楚。在本工作中，报道了影响该反应的几个因素，包括PMS和Se（IV）浓度、pH、Br−和天然有机物（NOM）对Se（IV）氧化的影响，以及不同水基质的影响。结果表明：随着pH（5.0 ~ 10.0）的增加，Se（IV）与PMS反应的二级速率常数从0.02 M−1 s−1增加到0.33 M−1 s−1,Se（IV）主要通过直接氧化途径氧化；这随着PMS和Se（IV）初始浓度的增加而增加，但被NOM的存在所抑制。然而，Br−的存在显著增强了Se（IV）在环中性pH下的氧化，但在碱性条件下的影响可以忽略不计。提出PMS氧化Se（IV）涉及在Br−存在下形成一种次溴酸/次溴酸（HOBr/OBr−）中间体，其形成得到DFT计算的支持。在此基础上，建立了含溴水中Se（VI）形成的动力学模型。此外，与Br−/NOM/PMS系统相比，Se（IV）的存在抑制了溴化消毒副产物（即溴仿和三溴乙酸）的形成。总的来说，这些结果有助于提高我们对含Br -的水中硒在普通氧化处理过程中的行为的理解。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.