Vapor pressures and thermodynamics of model mixtures of polycyclic aromatic compounds measured via the Knudsen effusion technique

ENVR 102

Jillian L. Goldfarb, Jillian_Goldfarb@brown.edu and Eric M. Suuberg, eric_suuberg@brown.edu. Division of Engineering, Brown University, 182 Hope Street, Providence, RI 02912
Polycyclic aromatic compounds (PACs) - ubiquitous environmental pollutants resulting from incomplete combustion - are often situated in the environment as multi-component solid phase mixtures. Some of these mixtures are easily characterized; many lack complete thermodynamic quantification due to their seemingly infinite number of constituents. What few data on mixtures are available in the literature show a vast range of experimental correlations. By fully characterizing the vapor pressure of a contaminated soil we are better equipped to predict the environmental distribution, fate and transport of these carcinogenic mixtures. The use of the novel nonisothermal Knudsen effusion technique enables the collection of real-time vapor phase composition, offering the potential to describe mixture behavior using activity coefficients, not only the ideal Raoult's law case. This paper presents data gathered on mixtures of PACs and an analysis of the ideality of mixture behavior through Raoult's law, an approximation often employed in risk assessment.