Vapor Pressures and Thermodynamic Properties of Complex Organic Mixtures

本课题研究的是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。关于高分子量化合物（如合成焦油和燃烧副产物）蒸气压的数据很少。含有杂原子的多环芳烃的数据就更少了。这些类型的化合物中的许多都是布朗菲尔德或超级基金场地的重要污染物。有一个重要的问题与现场的蒸汽暴露有关，蒸汽压力是决定暴露浓度的关键参数。同样，蒸汽压是决定污染物在现场外的某些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来解决这些基本热力学数据的缺乏问题。此外，人们对这种高分子量化合物混合物的蒸汽压和其他热力学性质的混合规律了解有限。本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有机污染物的混合物外，总是含有复杂的土壤基质。这个问题

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.