A data bank of parameters for two expressions for the temperature-dependence of the attractive coefficient, a (T), of the Peng-Robinson equation of state was compiled for 468 pure substances of varied polarity. The performances of the two expressions, a two-parameter form by Melhem et al. (1989) and a three-parameter form by Almeida et al. (1991) were compared through the root mean square (rms) and maximum (max) deviations in the prediction of the vapor pressure for these substances. The results show the superiority of the three-parameter for
The modified UNIFAC-Dortmund group contribution model is used for the correlation and prediction of salt effects in binary solvent-salt and ternary mixed solvent-salt systems. The long-range electrostatic interaction contribution, usually represented by a Debye-Hückel term, was empirically dropped. Previously published parameters for interactions between solvent groups (CH2, OH, CH3OH, H2O and CH3CO) were used, and group interactions between ions (Li+, Na+, K+, Ca+2, Cl-, Br-, NO3- and ACE-) and between ions and solvent groups have been estimated. The data base includes 29 binary and 56 ternary systems, used in part for the calculation of group interactions and in part for the testing of predictions
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