Comparative study of semitheoretical models for predicting infinite dilution activity coefficients of alkanes in organic solvents

Five nonelectrolyte solution models are used to predict infinite dilution activity coefficients (gamma(infinity)) of five linear, four branched, and two cyclic alkanes in 67 solvents at 25 degrees C, and the results are compared with experimental data. The models use two distinct approaches to the prediction of gamma(infinity). The solution of groups concept provides the basis for three versions of the UNIFAC model: original UNIFAC, gamma(infinity)-based UNIFAC, and modified UNIFAC (Dortmund). The MOSCED and the SPACE models avoid the group concept and use only pure component parameters. For a database of 737 Limiting activity coefficients, the SPACE model gave an average absolute error of 8.1%, and in only 13.3% of the cases were the errors worse than 15%. The modified UNIFAC model gave an absolute average error of 9.8%, and 32% of the predicted gamma(infinity) had errors larger than 15%. The SPACE approach also produced the most reliable estimations over a wide range of activity coefficient values.