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首页> 外文期刊>Environmental Science & Technology >Roles of Bromine Radicals and Hydroxyl Radicals in the Degradation of Micropollutants by the UV/Bromine Process
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Roles of Bromine Radicals and Hydroxyl Radicals in the Degradation of Micropollutants by the UV/Bromine Process

机译：溴/溴化溴/溴化物在微孔径降解中的作用

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摘要

The inevitable occurrence of Br~ in natural water affects the degradation kinetics of micropollutants in the UV/ chlorine process, the radical chemistry of which, however, is largely unclear. As Br~- in the UV/chlorine process first forms free bromine (HOBr/OBr~-), this study investigated the radical chemistry of the UV/bromine process for the degradation of selected micropollutants resistant to bromine, i.e., ibuprofen and benzoate, to focus on the roles of radicals. The actual quantum yields of HOBr and OBr~- by UV photolysis at 254 nm are 0.43 (±0.025) and 0.26 (±0.025) mol Einstein~(-1), respectively. Br~· and HO~. are generated first, and then, Br_2~(·-)~ is formed, with the signal detectable at 360 nm by laser flash photolysis. Compared with Cl~· in the UV/chlorine system, Br~· exists at higher concentrations (~10~(-12) M) in the UV/bromine system while HO~· exists at similar concentrations. In the UV/bromine process, reactive bromine species (RBS) dominates the degradation of ibuprofen, while HO~. dominates the degradation of benzoate. Br~· and Br_2~(·-) are reactive toward ibuprofen which second-order rate constants (k) were determined to be 2.2 × 109 and 5.3 × 10 M~7 s~(-1), respectively, by laser flash photolysis. Br~· was the major RBS for ibuprofen degradation by the UV/bromine treatment, whereas Br_2~(·-) increasingly contributed to ibuprofen degradation with increasing free bromine or Br~- concentrations. Br~· could be scavenged by HCO_3~- and natural organic matter (NOM), and the k with NOM was determined to be 2.6 × 10~4 (mg/L)~(-1) s~(-1). Both Br~· and Br_2~(·-) prefer to react with ibuprofen via electron transfer with activation energy barriers (△~(++)G~0_(SET)) of 1.35 and 7.78 kcal mol~(-1), respectively. RBS promoted the formation of hydroxylated products. Then free bromine, rather than RBS, was responsible for the formation of brominated products, increasing the total organic bromine (TOBr) and tribromomethane yields in the UV/bromine system. This study demonstrates for the first time the roles of RBS and HO~. in micropollutant degradation in the UV/bromine process.
机译：天然水中Br〜的必然发生影响微孔径在紫外/氯气过程中的降解动力学，然而，其中的自由基化学在很大程度上不清楚。作为BR〜 - 在UV /氯气过程中首先形成游离溴（HOBR / OBR〜 - ），研究了UV /溴化物的激进化学方法，用于降解抗溴，即布洛芬和苯甲酸的选定微渗透剂的降解专注于激进的作用。通过UV光解以254nm的HOBR和OBR〜 - OBR〜 - 0.43（±0.025）和0.26（±0.025）Mol Einstein〜（-1）的实际量子产率。 BR〜·和HO〜。首先生成，然后，通过激光闪光光解，在360nm处检测到BR_2〜（· - ）〜。与Cl〜·在UV /氯系统中相比，BR〜·UV /溴系统中的较高浓度（〜10〜（-12m）存在，而HO〜存在于类似浓度。在UV /溴化物过程中，反应性溴物质（RBS）占据了布洛芬的降解，而HO〜。主导苯甲酸盐的降解。 Br〜·和BR_2〜（· - ）对布洛芬的反应性，通过激光闪光光解，分别测定二阶速率常数（k）是2.2×109和5.3×10m〜7 s〜（1） 。 BR〜·是紫外/溴处理的布洛芬降解的主要RBS，而BR_2〜（· - ）越来越多地导致布洛芬与增加的游离溴或BR〜 - 浓度降解。 BR〜·可以通过HCO_3〜 - 和天然有机物（NOM）清除，并且具有NOM的K为2.6×10〜4（Mg / L）〜（-1）S〜（-1）。 BR〜·和BR_2〜（· - ）均优选通过电子转移与可激活能量屏障（χ〜（++）g〜0_（设定））分别为1.35和7.78 kcal〜（-1）的电子转移反应。 RBS促进了羟基化产物的形成。然后游离溴而不是RBS，负责形成溴化产品，增加UV /溴体系中的总有机溴（TOBR）和Tribromomethane产率。这项研究首次展示了RB和Ho〜的角色。在UV /溴化过程中的微核性降解。

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  • 来源
    《Environmental Science & Technology》 |2020年第10期|6415-6426|共12页
  • 作者

    Kaiheng Guo; Shanshan Zheng; Xuewen Zhang; Liu Zhao; Shaomin Ji; Chunyan Chen; Zihao Wu; Ding Wang; Jingyun Fang;

  • 作者单位

    Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and Engineering Sun Yat-Sen University Guangzhou 510275 P R. China;

    Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and Engineering Sun Yat-Sen University Guangzhou 510275 P. R. China State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology Harbin 150090 P. R. China;

    Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and Engineering Sun Yat-Sen University Guangzhou 510275 P. R. China;

    Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and Engineering Sun Yat-Sen University Guangzhou 510275 P. R. China;

    School of Chemicals Engineering and Light industry Guangdong University of Technology Guangzhou 510006 P. R. China;

    Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and Engineering Sun Yat-Sen University Guangzhou 510275 P. R. China;

    Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and Engineering Sun Yat-Sen University Guangzhou 510275 P. R. China;

    Independent Researcher Calgary Alberta T3L 2 V2 Canada;

    Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and Engineering Sun Yat-Sen University Guangzhou 510275 P. R. China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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