A new group contribution method based on GCVOL model developed by Elbro et al. in 1991 [Elbro, H. S.; Fredenslund, A.; Rasmussen, P. Ind. Chem. Eng. Res. 1991, 30, 2576–2582] is proposed for the estimation of ionic liquids density over a wide range of temperature and pressure. A total of 102 new groups for ionic liquids were introduced to the already 60 existing groups revised and proposed in 2003 by Ihmels and Gmehling [Ihmels, E. C.; Gmehling, J. Ind. Chem. Eng. Res. 2003, 42, 408–412]. These groups were proposed based on a collection of density data from literature. The databank contains data of 864 different ionic liquids, including dicationic and tricationic species, and a total of 21 845 data points, covering a temperature range of 251.62–473.15 K and a pressure range of 0.1–300.0 MPa. An average absolute relative deviation (%AARD) of 0.83% was obtained, indicating that our model is able to predict densities of a great variety of ionic liquids accurately.

Several models based on the Group Contribution concept and on the Corresponding States Principle were reviewed for the estimation of vapor pressures and enthalpies of vaporization of fatty acid methyl and ethyl esters commonly occurring in biodiesel. The accuracy of each model was tested by comparing its output values to experimental data obtained from the literature. For vapor pressures, the number of occurrences where the methods failed completely have also been analyzed. Efforts were made to identify the best method for the estimation of each property and it was observed that the models' reliability depend on the type of ester and on the operational conditions (pressure and temperature) considered.

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Liquid−liquid equilibria (LLE) data play an important role in the project and design of separation processes. The aim of this work was to study the LLE data of the solubility (binodal) curves and tie-lines for the glycerol (1) + ethanol (2) + coconut biodiesel (3) system at two different temperatures [(293.15 and 323.15) K], at atmospheric pressure. From the experimental data, it could be observed that the relative mutual solubility of ethanol is higher in the glycerol phase than the biodiesel phase. A consistency analysis has been performed by using the Othmer−Tobias correlation. The experimental liquid−liquid data were correlated by using two local composition models (NRTL and UNIQUAC) for the activity coefficient calculation. From these models, binary parameters have been determined. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the ethanol used as a solvent.

A comprehensive study regarding the estimation of normal boiling points, critical temperatures, critical pressures, and acentric factors of biodiesel-related esters is presented. Such properties are crucial for simulations of chemical processes involving biodiesel. Although reliable experimental data are available for some esters, their determination for all the existing biodiesel components is an expensive and cumbersome task. In view of that, this work aimed to investigate the performance of group contribution and corresponding state models in the calculation of these properties. The estimation models were tested in terms of accuracy and of the plausibility of combining experimental and calculated values without violating the expected physical behavior for corresponding pairs of esters and for esters belonging to the same homologous series. The main outcome of this work is a recommendation of the most feasible models for engineering applications.