We used ultraviolet and heat (UV-heat) to costimulate HCl, HBr, and HI to yield Cl^•, Br^•, and I^• for Hg⁰ removal. Electron spin resonance (ESR) confirmed the radical formation. Cl^•/Br^•/I^• were found to play the leading roles in Hg⁰ removal, Br₂/I₂ formed from the heat catalysis of HBr/HI also played key roles. The costs for removing 80% Hg⁰ with UV-heat/HCl, UV-heat/HBr, and UV-heat/HI were calculated to be 0.03, 2.4, and 36.9 USD/lb-Hg⁰, respectively. Rising heat catalysis temperature favored the Hg⁰ removal. Declining flue gas residence time and adding NO and SO₂ impaired the Hg⁰ removal by Cl^• and Br^• but did not include I^•. Kinetics analyses indicated that UV increased the Hg⁰ removal rate by 15.5 times for HCl, by 1.3 times for HBr, and by 0.2 time for HI. Radical quenching test with tertiary butanol (TBA) and CO₂ indicated that Cl^• and Cl₂^•– contributed almost 100% and <5% to Hg⁰ removal, respectively. Density functional theory (DFT) calculation gives the reactivity order of oxidizing species toward Hg⁰, that is, Cl^• > Br^• > I^• > I₂ > Br₂ > Cl₂. The environmetnal implications were proposed finally.

中文翻译：

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Hg ⁰去除中卤素自由基的反应行为和成本-效果：性能，动力学和机理

我们使用紫外线和热能（UV-heat）共同估算HCl，HBr和HI，以生成Cl ^•，Br ^•和I ^•来去除Hg ⁰。电子自旋共振（ESR）证实了自由基的形成。发现Cl ^• / Br ^• / I ^•在Hg ⁰去除中起主要作用，由HBr / HI的热催化形成的Br ₂ / I ₂也起关键作用。计算出用紫外线加热/ HCl，紫外线加热/ HBr和紫外线加热/ HI去除80％Hg ⁰的成本分别为0.03、2.4和36.9 USD / lb-Hg ⁰。热催化温度升高有利于汞⁰去除。降低烟气停留时间并添加NO和SO _2会损害Cl ^•和Br ^•去除Hg ^0的能力，但不包括I ^•。动力学分析表明，对于HCl，UV将Hg ^0的去除率提高了15.5倍，对于HBr，提高了1.3倍，对于HI，提高了0.2倍。用叔丁醇（TBA）和CO _2进行的自由基淬灭试验表明，Cl ^•和Cl ₂ ^{• –}分别对Hg ^0的去除贡献了近100％和<5％。密度泛函理论（DFT）计算给出了氧化物质对Hg ⁰（Cl ）的反应顺序^• > Br ^• > I ^• > I ₂ > Br ₂ > Cl ₂。最后提出了环境意义。