Prediction of equilibrium partitioning of nonpolar organic solutes in water-surfactant systems by UNIFAC and COSMO-RS models

Journal
Chemical engineering & technology  
Volume
29
Issue
5
Start Page
567
End Page
573
Citation
Chemical Engineering and Technology 29 (5): 567-573 (2006-05-01)
Publisher DOI
10.1002/ceat.200600015
Scopus ID
2-s2.0-33646754218
Publisher
Wiley-VCH Verl.-Ges.
In the present study the potential of two thermodynamic-based models (the group-contribution UNIFAC model and the a priori predictive COSMO-RS model) to predict solute partitioning in aqueous surfactant solutions is evaluated. In order to take into account the small size of micelles, the UNIFAC model was extended by the interfacial contribution based on the Gibbs-Thompson equation. The applicability of the approach was successfully proved for the partitioning of nonpolar solutes (toluene, p-xylene) in aqueous solutions of nonionic surfactants. The original COSMO-RS model underestimates the concentration of the solute in the aqueous phase in the case of micellar systems since it does not account for the small size of micelles. At the same time, this model gives quantitative results for the octanol/water partition coefficients of both solutes under study leading to the conclusion that the affinity of both solutes to a certain solvent is well described. Thus, extending the COSMO-RS by the interfacial term seems to be promising.
DDC Class
540: Chemie