Development of a Demonstrable Model of Dioxin Formation

由申请人）：我们将开发形成的示范模型， 多卤代二苯并二恶英和二苯并呋喃（PXDD/F）、持久性自由基和其他 有害废物燃烧和热反应产生的有毒卤代烃。这 包括多氯二苯并对二恶英和二苯并呋喃（PCDD/F）、多溴二苯并对 二恶英/二苯并呋喃（PBDD/F）、混合溴/氯二苯并对二恶英/二苯并呋喃（PBCDD/F），以及 持续共振稳定，表面缔合，半醌型自由基，是关键反应 中间体和污染物。这将通过结合机械研究来实现 使用与气相色谱/质谱仪（GC-MS）耦合的高温流动反应器 使用激光光解/激光诱导荧光和荧光的分析系统和反应动力学研究 激光光解/激光电离飞行时间质谱法。我们将：1）确定 2）决定了颗粒尺寸如何从纳米级到 微米尺寸范围影响形成速率和产物分布，3）测量基本自由基- PXDD/F形成过程中关键反应的分子反应速率; 4）采用从头算和半经验方法 建模技术来计算关键反应的速率，以及5）将这些信息合并到一个 CHEMKIN反应动力学模型中详细、全面的PXDD/F形成模型 平台我们怀疑，过渡金属，表面介导的PCDD/F形成途径相关 涉及在细颗粒和超细颗粒的表面上形成持久的还原性自由基。因此在 除了通过暴露于超细颗粒来确定PCDD/F的生物传递外，我们还将 表征持久性自由基（PFR）的形成及其在超细粉体毒性中的作用 粒子我们的实验研究PCDD/F的形成和建模研究（包括 项目3）的实验结果将使我们能够更好地阐明气相的相对贡献 和表面介导的过程形成PXDD/F。本项目开发的模型将

by applicant): We will develop demonstrable models of the formation of polyhalogenated dibenzo-p-dioxins and dibenzofurans (PXDD/F), persistent free radicals, and other toxic halogenated hydrocarbons from the combustion and thermal reactions of hazardous wastes. This includes polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), polybrominated dibenzo-p- dioxin/dibenzofurans (PBDD/F), mixed bromo/chloro dibeno-p-dioxins/dibenzofurans (PBCDD/F), and persistent resonance stabilized, surface-associated, semiquinone type radicals that are key reaction intermediates and pollutants. This will be accomplished through a combination of mechanistic studies using a high-temperature flow reactor coupled to a gas chromatograph/mass spectrometer (GC-MS) analytical system and reaction kinetic studies using laser-photolysis/laser induced fluorescence and laser photolysis/laser ionization time-of-flight mass spectrometry. We will: 1) determine the role of chlorinated benzenes in the formation of PCDD/F, 2) determine how particle size from the nanometer to micron size regime effects formation rates and product distributions, 3) measure elementary radical- molecule reaction rates of key reactions in formation of PXDD/F, 4) use ab initio and semi-empirical modeling techniques to calculate rates of key reactions, and 5) consolidate this information into a detailed, comprehensive model of PXDD/F formation within the CHEMKIN reaction kinetic modeling platform. We suspect that transition-metal, surface-mediated PCDD/F formation pathways are related to formation of persistent, reductive radicals on the surfaces of fine and ultra-fine particles. Thus, in addition to determining the biodelivery of PCDD/F via exposure to ultra-fine particles, we will characterize the formation of persistent free radicals (PFRs) and their role in the toxicity of ultrafine particles. Our experimental-studies of PCDD/F formation and modeling studies (incorporating the experimental results of Project 3) will allow us to better elucidate the relative contributions of gas-phase and surface-mediated processes to the formation of PXDD/F. The models developed in this project will