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 a ctivity coefficients (gamma(infinity)) of five linear, four branched, and t wo cyclic alkanes in 67 solvents at 25 degrees C, and the results are compa red with experimental data. The models use two distinct approaches to the p rediction of gamma(infinity). The solution of groups concept provides the b asis for three versions of the UNIFAC model: original UNIFAC, gamma(infinit y)-based UNIFAC, and modified UNIFAC (Dortmund). The MOSCED and the SPACE m odels avoid the group concept and use only pure component parameters. For a database of 737 Limiting activity coefficients, the SPACE model gave an av erage absolute error of 8.1%, and in only 13.3% of the cases were the error s 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 wi de range of activity coefficient values.