Improved models for the prediction of activity coefficients in nearly athermal mixtures: Part I. Empirical modifications of free-volume models

Georgios M. Kontogeorgis, Philipos Coutsikos, Dimitrios Tassios, Aage Fredenslund

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Mixtures containing exclusively normal, branched and cyclic alkanes, as well as saturated hydrocarbon polymers (e.g. poly(ethylene) and poly(isobutylene)), are known to exhibit almost athermal behavior. Several new activity coefficient models containing both combinatorial and free-volume contributions are proposed, tested and compared with classical models. It is shown that it is generally difficult to simultaneously predict the activity coefficients of both a short-chain solute in a long-chain solvent (γ1) and a long-chain solute in a short-chain solvent (γ2) with a single model. In addition, only few models can be applied to solutions with polymers. One of the proposed models (p-FV), however, can successfully predict both γ1 and γ2, and can also be extended to mixtures containing polymers.
Original languageEnglish
JournalFluid Phase Equilibria
Volume92
Pages (from-to)35-66
ISSN0378-3812
DOIs
Publication statusPublished - 1994

Keywords

  • Theory
  • Excess functions
  • Activity coefficients
  • Mixtures of hydrocarbons
  • Free-volume effects
  • Polymer solutions

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