Measurement and Correlation of the Solid−Liquid−Gas Equilibria for the Carbon Dioxide + S-(+)-Ibuprofen and Carbon Dioxide + RS-(±)-Ibuprofen Systems

The pressure p−temperature T projections of solid−liquid−gas (S−L−G) three-phase coexistence lines for the carbon dioxide + S-(+)-ibuprofen system and the carbon dioxide + RS-(±)-ibuprofen system were measured by the first melting point method in which the initial appearance of the liquid phase was observed. The experimental p−T projections of the S−L−G lines for the two systems were quite different from each other. The experimental p−T projections of the S−L−G lines were also correlated by the Peng−Robinson equation of state with a binary interaction parameter introduced into an attraction term. The present model gave good correlation results for all of the experimental S−L−G lines with maximum average absolute relative deviations of 0.14% for the carbon dioxide + S-(+)-ibuprofen system and 0.90% for the carbon dioxide + RS-(±)-ibuprofen system.