Tracing the critical locus for binary fluid mixtures using molecular simulations

Phase behavior at high temperatures and pressures have numerous applications, particularly in separation processes. The critical locus for various binary mixtures including non-polar, polar, and ionic species using grand canonical Monte Carlo simulations with histogram reweighting was deterined. The critical point is determined using the finite-size scaling approach of Bruce and Wilding. Different classes of the critical locus in binary mixtures, e.g., Class I and Class IIIb, are seen for systems including methane-ethane, methane-water, and water-NaCl. The choices for the intermolecular potentials and the combining rule between species have a significant impact on the critical locus. The effect of including polarization in the methane-water mixture on the critical locus is elucidated. This is an abstract of a paper presented at the AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 10/30/2005-11/4/2005).