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首页> 外文期刊>Environmental Science & Technology >System To Measure Relative Rate Constants of Semivolatile Organic Compounds with Hydroxyl Radicals
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System To Measure Relative Rate Constants of Semivolatile Organic Compounds with Hydroxyl Radicals

机译:用羟基自由基测量半挥发性有机化合物相对速率常数的系统

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摘要

A system to determine rate constants for the reaction of the hydroxyl radical with semivolatile organic compounds undertropospheric conditions is described. The system incorporates on-line mass spectrometric . detection to improve experimental time resolution and to minimize sampling volume. The reaction apparatus is heated to provide detectable vapor phase levels of semivolatile compounds without sample pre-concentration. Temperature control of the system also allows investigation of the temperature dependence of OH-organic reactions. OH radicals are generated by the photolysis of O_3 in the presence of water vapor to avoid the wall effects associated with the more commonly used alkyl nitrite photolysis. The temperature dependence of the OH-toluene reaction is investigated from 276 to 397 K in 1 atm of He and from 296 to 363 K in 1 atm of N_2/O_2. In He, the OH-toluene reaction rate constant at 298 K is (5.9 ± 1.5) x 10~(-12) cm~3 s~(-1), and in N_2/O_2, the rate constant at 298 K is (5.8 ± 1.5) x 10~(-12) cm~3 s~(-1). Rate constants for the reaction of OH with 4,4′-dichlorobiphenyl from 329 to 366 K are also reported. Over this temperature range, the 4,4′-dichlorobiphenyl reaction with OH is only weakly temperature dependent. From the experimentally determined temperature dependence, the OH rate constant at 298 K of 4,4′-dichlorobiphenyl is (2.0 ± 0.5) x 10~(-12) cm~3 s~(-1).
机译:描述了确定对流层条件下羟基自由基与半挥发性有机化合物反应速率常数的系统。该系统包含在线质谱仪。检测以提高实验时间分辨率并最大程度地减少采样量。加热反应装置以提供可检测的半挥发性化合物的气相水平,而无需样品预浓缩。系统的温度控制还允许研究OH-有机反应的温度依赖性。在水蒸气的存在下,O_3的光解会产生OH自由基,从而避免了与更常用的亚硝酸烷基酯光解相关的壁效应。在1 Atm的He中从276到397 K在N_2 / O_2的1 atm中从296到363 K在OH-甲苯反应中研究了温度依赖性。在He中,298 K的OH-甲苯反应速率常数为(5.9±1.5)x 10〜(-12)cm〜3 s〜(-1),在N_2 / O_2中,在298 K的速率常数为( 5.8±1.5)x 10〜(-12)cm〜3 s〜(-1)。还报道了从329 K到366 K的OH与4,4'-二氯联苯反应的速率常数。在此温度范围内,与OH的4,4'-二氯联苯反应仅与温度密切相关。从实验确定的温度依赖性来看,4,4'-二氯联苯在298 K下的OH速率常数为(2.0±0.5)x 10〜(-12)cm〜3 s〜(-1)。

著录项

  • 来源
    《Environmental Science & Technology》 |1996年第1期|p.301-306|共6页
  • 作者单位

    School of Public and Environmental Affairs and Department of Chemistry, Indiana University, Bloomington, Indiana 47405;

  • 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);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境化学;
  • 关键词

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