Group Contributions in Mixtures

Abstract

Oneof the areas in which thermodynamics finds an important application is in the development and design of processes for the recovery and purification of the relatively simple organic compounds. Since many such processes exploit small differences in the distribution of a number of compounds between equilibrium phases, the needs in this area are generally for quite accurate descriptions of the distributions of components between phases over some range of temperature and pressure. Indeed, the needs for accuracy are frequently great enough and the systems are complex enough that strictly theoretical means of predicting equilibria have been of limited use. As a consequence, the practice of depending primarily upon direct experimental measurement of equilibria is widespread. Since such measurements are frequently difficult, tedious, and costly, the number of measurements must be held to a minimum.

Thermodynamic Group Contributions for Hydroxyl, Amino, and Methylene Groups

“…2 by eubtracting the alkane in heptane values for each corresponding carbon number as in Eq. 7. These values were 1320 cal/mole for the hydroxyl group and 1490 cal/ mole for the amino group from organic to vapor phases ( Table 11).…”

Effect of Water Saturation on H2 and CO Solubility in Hydrocarbons

“…Saturated aqueous solutions of hydrocarbons at low to moderate temperatures are usually very dilute solutions, therefore hydrocarbon solubilities in water and vice versa could be directly related to the predictions of activity coefficients at infinite dilution. Deal et al [15,16] presented an extensive correlation for activity coefficients at infinite dilution at 298 K with molecular structure and the interaction of various structural groups in the solution. The resulting correlations are simple and easily applicable to homologous series in water.…”

John M. Prausnitz: Bridging abstractions and realities

“…Group contribution methods for pure component properties and for infinite dilution activity coefficients had been developed in the 1950s. The origins and extensions to mixtures are summarized very well by Deal and Derr . An innovation by Grant Wilson was the “Solution Of Groups” concept for excess properties, where it was not molecules, but small collections of atoms making up the substances, that possessed solution properties.…”