Solvation in Supercritical Fluids

Professor Mark Maroncelli of Pennsylvania State University is supported by a grant from Experimental Physical Chemistry to perform experimental and theoretical studies on the nature of solvation of molecules in supercritical fluids. Currently in this subarea of ultrafast solution dynamics, there are anomalies in the results that may be interpreted as density inhomogeneities local to the solute (although this is still controversial) and, therefore, supercritical fluids are more complex than previously thought. A simple nonreactive solute/supercritical solvent system will be quantitatively modeled and then simulations will be performed to view the molecular interactions from spatial and dynamic points of view. Analytical models will be constructed that one could use to predict the solvation effects using well-known solute and solvent properties. This model will be used to predict experimental observations on solute diffusion, relaxation and chemical reaction rates in supercritical fluids at various temperatures and pressures. Professor Maroncelli will conduct experiments simultaneously with theoretical work. Anthracene in supercritical carbon dioxide is one chemical system being probed.

This work is especially timely because of the interest in supercritical solvents for a wide variety of applications such as environmentally benign processing and remediation as well as separations and extraction. Supercritical solvation has extremely important industrial applications, and a more complete theoretical understanding of this phenomenon will have an important impact.