Phase and Partition Behavior of Multiple-Component PAH Mixture Systems

摘要

Polycyclic aromatic hydrocarbons (PAHs) are common components of petroleum and byproducts of fuel conversion. Additionally, it is well understood that manufactured gas production resulted in widespread soil and water contamination by tars and non- aqueous phase liquids that contain PAHs as mixtures of many similarly structured compounds. The phase and partitioning behavior of these complicated mixtures must be well characterized in order to assess risk, fate and transport, and remediation of these ubiquitous and potentially carcinogenic environmental contaminants. This study utilizes differential scanning calorimetry, melting temperature analysis, X-ray diffraction, and effusion techniques to measure the solid-liquid and solid-vapor equilibrium properties of PAH mixtures. Results show that binary and ternary PAH mixtures exhibit eutectic points and solid azeotropes , the formation of which strongly influences fusion and sublimation enthalpies. This complicated, non- ideal behavior gives way to true tar character as the number of components in the PAH mixtures increases. In other words, as the energetics of multicomponent PAH mixtures approach a liquid limit, the vapor pressure of such mixtures can be predicted by ideal thermodynamics, i.e., Raoult's law. This work is part of a broad study of PAH mixtures. Preliminary results of upcoming work include aqueous solubility and sorption behavior of PAH mixtures. Much of this work requires original and unique experimental design that is worthy of presentation and discussion.