Vapor Pressures and Thermodynamic Properties of Complex Organic Mixtures

该项目涉及轻微挥发性有机化合物(VOC)或半挥发性有机化合物(SVOC)的蒸气压问题。关于组成焦油和燃烧副产物等高分子化合物的蒸汽压的数据很少。对于含有杂原子的多环芳烃，数据甚至更少。其中许多类型的酚醛化合物在棕地或超级基金网站作为污染物是重要的。与现场的蒸汽暴露有关的问题非常令人担忧，而蒸汽压力是决定暴露浓度的关键参数。同样，蒸汽压是决定某些污染物异地运输方式的关键因素，也是热解吸过程的设计参数。该项目将通过一系列旨在填补关键空白的测量，解决此类基本热力学数据的匮乏问题。此外，对这些高分子化合物混合物的蒸汽压和其他热力学性质的混合物规则的了解也是有限的。这项研究还将寻求解决与高分子量体系的混合行为有关的问题。什么时候可以使用理想的混合定律，如拉乌尔定律，来描述污染物混合物的行为？最后，棕地和超级基金场地除了污染物有机物的混合物外，总是含有复杂的土壤基质。问题是 土壤在吸附感兴趣的化合物方面起什么作用？特别是，大多数土壤中少量但重要的碳含量在决定有机污染物的蒸汽压方面起到了什么作用？在什么条件下？在这项工作的吸附部分正在审查的一个附属问题是，为了将污染物的残余蒸气压降低到可接受的水平，热解吸过程的温度必须达到多高？这个项目中的方法主要是试验性的，但将始终保持对确定可靠属性关联的需要的看法。项目团队已经在两个关键领域取得了成功--低挥发性蒸汽压的测量 化合物及其混合物，以及有机物在无机基质中的碳上的吸附。

This project is concerned with the question of vapor pressures of marginally volatile organic compounds (VOC) or Semi-Volatile Organic Compounds (SVOC). Few data exist on the vapor pressures of high molecular weight compounds, such as make up tars and combustion byproducts. Even fewer data exist for polycyclic aromatics that contain heteroatoms. Many of these types pf compounds are important as contaminants in Brownfields or Superfund sites. There is significant concern related to vapor exposures at sites, and vapor pressure is the key parameter that determines exposure concentrations. Likewise, vapor pressure is a key factor determining some modes of transport of contaminants off site, as well as a design parameter for thermal desorption processes. This project will address the paucity of such basic thermodynamic data, through a series of measurements designed to fill in key gaps. In addition, there is only limited understanding of the mixture rules governing vapor pressure and other thermodynamic properties of mixtures of such high molecular weight compounds. This study will also seek to address questions related to mixture behavior of systems of high molecular weight. When is it acceptable to use ideal mixing laws, such as Raoult's Law, to characterize the behavior of mixtures of contaminants? Finally, Brownfields and Superfund sites always contain a complex soil matrix, in addition to the mixture of contaminant organics. The question is, what role does the soil play in adsorbing the compounds of interest? In particular, what role does the small but significant carbon content of most soils play in determining vapor pressure of organic contaminants? At what conditions? A subsidiary question to those being examined in the adsorption portion of this work is, how high must temperatures of thermal desorption processes be, in order to reduce the residual vapor pressures of contaminants to acceptable levels? The approach in this project is primarily experimental, but will always keep a view towards the need to determine reliable property correlations. The project team is already experienced in two critical areas for success on this project- measurements of vapor pressures of low volatility compounds and their mixtures, and adsorption of organics onto carbons in inorganic matrices.