Josefa García

Experimental excess volumes of organic carbonate+alkane systems. Estimation of the parameters of the Nitta–Chao model for this kind of binary mixture

Excess volumes at 298.15 K and atmospheric pressure of some organic carbonate+alkane binary systems have been measured using an Anton Paar 602 HP densimeter. For the first time, published data on excess enthalpies, excess volumes, excess Gibbs energies of the above-mentioned binary systems together with the vaporisation enthalpies and the molar volumes of the pure organic carbonates, were used to estimate the interaction parameters between the carbonate group O–CO–O and the methyl and methylene groups, CH3, CH2, respectively. The mean deviations between experimental and theoretical values were smaller than 6% for all the properties. We have also compared our results with those obtained by Garcia etal. with the Original, Tassios etal., Larsen etal. and Gmehling etal. versions of the UNIFAC model and with those obtained by Kehiaian etal. using the DISQUAC model.

Estimation of parameters of Nitta–Chao model for ester+1-alkanol mixtures

Abstract An updated database with experimental values on vapor–liquid equilibria, activity coefficient at infinite dilution, enthalpies of mixing and excess molar volumes of alkyl alkanoate+1-alkanol binary systems was used to redetermine structure and interaction parameters of the Nitta–Chao model. We have compared the theoretical results obtained with the Nitta–Chao model and our parameters with the experimental data. The percentual mean deviations with the parameters calculated in this work are quite good for all properties studied. We have used the same database to analyse the quality of the predictions of three versions of UNIFAC model for this type of mixtures.

Experimental and predicted excess enthalpies of the 2,2,2-trifluoroethanol–water–tetraethylene glycol dimethyl ether ternary system using binary mixing data

Excess enthalpies of the ternary mixture 2,2,2-trifluoroethanol–water–tetraethylene glycol dimethyl ether and the corresponding binary mixtures at 298.15 K have been measured using a standard Calvet microcalorimeter. Wilson, NRTL, UNIQUAC and Wang et al. models have been used to correlate the binary excess enthalpies and, using the parameters obtained, to predict ternary excess molar enthalpies, HE. Several empirical equations predicting ternary-mixture properties from the binary-mixing data have been also examined.

Estimation of parameters of Nitta-Chao model for linear monoether + 1-alkanol mixtures

We have estimated the interaction parameters for ether and hydroxyl groups using an extensive experimental database of vapour-liquid equilibria, activity coefficients at infinite dilution, enthalpies of mixing and volumes of mixing of linear monoether + 1-alkanol binary systems. The theoretical results obtained with the parameters proposed are significantly closer to the experimental values than those determined with the parameters of Eckart et al. In addition, the values of thermodynamic properties obtained by the Nitta-Chao model with both set of parameters have been compared with the predictions resulting from other models, such as the DISQUAC model and the UNIFAC model, in its original version and those of Dang and Tassios, Larsen et al. (UNIFAC-Lingby) and Gmehling et al. (UNIFAC-Dortmund).

Phase equilibria and pVT predictions for alkyl carbonate + n-alkane systems using equations of state

Abstract In this paper experimental data available in the literature on vapor–liquid equilibria, densities and excess molar volumes of dialkyl carbonate+ n -alkane mixtures on broad temperature and pressure ranges have been used in order to test four equations of state (EoS): Soave–Redlich–Kwong (SRK), Peng–Robinson (PR), Patel–Teja (PT) and Dohrn–Prausnitz (DP). For the pure components, when the critical parameters were not available in the literature, the group contribution method of Klincewicz and Reid was used to estimate the critical temperature and pressure. For dialkyl carbonate+ n -alkane mixtures we have determined the binary interaction parameter, k ij , using experimental vapor–liquid equilibria data and then with these parameters the pVTx values were predicted. The best correlations for VLE and predictions for the volumetric behavior were obtained with PR and PT equations.

Analysis of the molecular interactions of organic anhydride+alkane binary mixtures using the Nitta–Chao model

Abstract The Nitta–Chao EOS group-contribution model, based on cell theory, is used to study the interactions of the organic anhydride+n-alkane binary mixtures. A database of excess enthalpies, excess Gibbs energies and excess volumes for this kind of mixtures, together with molar volumes and vaporization enthalpies of pure organic anhydrides, were used to calculate the characteristic parameters of the Nitta–Chao group-contribution model. In order to enlarge the database, the excess molar volumes at 298.15 K for the binary mixtures of pentanoic and hexanoic acid anhydrides with an n-alkane are reported. An analysis of the interactions is presented with the estimation of the changes of the mean numbers of contacts between the different groups during the mixing process. The influence of the dispersive and non-dispersive interaction energy parameters on the excess volumes and excess enthalpies is also presented. The model consistently describes the experimental data of organic anhydride+n-alkane mixtures, i.e. the excess volumes increase when the anhydride chain length decreases and when alkane chain length increases. The symmetry of the VE(x) curves and the sign and magnitude of the excess volumes are strongly dependent on the lengths of the alkane and of the organic anhydride.

Modelling of PVT for some poly alkylene glycol lubricants using Sako–Wu–Prausnitz EOS

Abstract The group contribution approach of Elvassore et al. has been used in combination with the three parameters cubic equation of state of Sako et al. with the aim to estimate PVT properties of poly alkylene glycols (PAGs), whose use has been proposed as lubricants for some hydrofluorocarbon (HFC) refrigerants. The contribution to the characteristic parameters of the equation of state of the ether CH 3 O and CH 2 O groups has been calculated using a database containing densities of monoethers and of a polyether (mono ethyleneglycol dimethyl ether (MEGDME)). Then densities over a wide range of temperatures and pressures have been estimated for longer chain PAGs, obtaining good accuracy.

Analysis of the interaction between cycloalkanes and 1-alkanols by means of Nitta Chao group contribution model

Abstract The interaction between cyclic alkane (CH 2 r ) and hydroxyl (OH) structural groups was revised within the framework of Nitta Chao group contribution model. New interaction parameters were calculated using an updated database, and previous results were clearly improved. Comparison was established with other group contribution models (UNIFAC, DISQUAC).

Modelling thermodynamic properties of iodoalkane + alkane systems using group contribution models

The experimental data available in the literature for the binary systems 1-iodoalkane and α,ω-diiodoalkane with alkanes are used to determine the interaction parameters of the iodine and methyl or methylene groups of the Nitta–Chao equation-of-state group contribution model and of three versions of the UNIFAC model due to Tassios et al., Larsen et al. and Gmehling et al. The results for the thermodynamic properties obtained using the new parameters of the three versions of the UNIFAC and Nitta–Chao models are compared with those of the DISQUAC model. Liquid–liquid equilibria data of α,ω-diiodoalkane + alkane mixtures were used to check the obtained interaction parameters. An analysis of the dispersive and non-dispersive interactions is presented with the estimation of the changes of the mean numbers of contacts between the iodine, methyl and methylene groups during the mixing process.