Investigating the effects of methanol and n-octane entrainers on solubility and microscopic structure in supercritical carbon dioxide

COMP 183

Kelly E. Anderson, Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455 and J. Ilja Siepmann, siepmann@chem.umn.edu, Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455-0431.
Isobaric-isothermal Gibbs ensemble Monte Carlo simulations were carried out to investigate the effects of entrainer presence on solubility and structure of hexamethylbenzene and benzoic acid in supercritical carbon dioxide. The entrainers methanol and n-octane were used to contrast polar versus non-polar cosolvent effects. The simulations using the transferable potentials for phase equilibria–united atom (TraPPE–UA) force field indicate that the presence of either cosolvent promotes solubility relative to the neat solvent system. These results are consistent with the experimental results of Dobbs, Wong, Lahiere, and Johnston. A detailed structural analysis is performed to relate changes in the microscopic structure to the solubility enhancement.