Phase Equilibrium Research Papers - Academia.edu (original) (raw)

This work shows the experimental data of excess properties at several temperatures and the vapor–liquid equilibria (VLE) obtained for four binary systems of alkyl methanoates (methyl to butyl) with decane, all measured at constant... more

This work shows the experimental data of excess properties at several temperatures and the vapor–liquid equilibria (VLE) obtained for four binary systems of alkyl methanoates (methyl to butyl) with decane, all measured at constant pressure of 101.32kPa. The isobaric VLE data were thermodynamically consistent according to the Fredenslund test and did not present an azeotrope. The experimental data of HmE

Solid-liquid equilibrium (SLE) for binary mixture of Propafenone Hydrocloride (PP) with Metoprolol Tartrate (MT) was investigated using differential scanning calorimetry (DSC) and corresponding activity coefficients were calculated.... more

Solid-liquid equilibrium (SLE) for binary mixture of Propafenone Hydrocloride (PP) with Metoprolol Tartrate (MT) was investigated using differential scanning calorimetry (DSC) and corresponding activity coefficients were calculated. Simple eutectic behavior for this system was observed. The excess thermodynamic functions: G(E) and S(E) for the pre-, post-, and eutectic composition have been obtained using the computed activity coefficients data of the eutectic phase with their excess chemical potentials μi(E) (i=1, 2). The experimental solid-liquid phase temperatures were compared with predictions obtained from available eutectic equilibrium models. The results indicate non-ideality in this mixture. Also, the compatibility of each component and their eutectic mixture with usual excipients was investigated, and the DSC experiments indicate possible weak interactions with α-lactose monohydrate and compatibility with corn starch. The results obtained were confirmed by FT-IR measurements.

A computer algorithm has been developed to determine the cloud and shadow point curves of polydisperse polymer/solvent systems using continuous thermodynamics to represent the polymer. The algorithm is based upon the work of Michelsen... more

A computer algorithm has been developed to determine the cloud and shadow point curves of polydisperse polymer/solvent systems using continuous thermodynamics to represent the polymer. The algorithm is based upon the work of Michelsen [M.L. Michelsen, Fluid Phase Equilibria, 4 (1980), pp. 1–10] and Koak [N. Koak, Polymer Solution Phase Behaviour, PhD Thesis, University of Calgary, Calgary, 1997] where a Newton–Raphson procedure is used to solve the equations defining phase equilibrium for fixed phase segment fractions between 0 and 1. The equations have been developed with the Sanchez–Lacombe equation of state which allows the continuous system to be defined by a set of five equations in five unknowns. Numerical integration is used to determine the values of the indefinite integrals involved. The cloud and shadow curves for a polydisperse polyethylene/n-hexane system were found at 6 bar using both a log-normal distribution and a Schulz–Flory distribution to represent the polyethylene. Compositions of the cloud point curve covered the entire composition range showing the model's behavior in high temperature regions, a hypothetical liquid–vapour critical point and a three-phase point when the log-normal distribution was used. The cloud and shadow point curves of a polyethylene/ethylene system were also found and indicated a high pressure critical point.

For the geological sequestration of carbon dioxide to prevent global warming, the phase equilibrium data for water and carbon dioxide mixture play an important role in process design and operation. In this work, the nonrandom lattice... more

For the geological sequestration of carbon dioxide to prevent global warming, the phase equilibrium data for water and carbon dioxide mixture play an important role in process design and operation. In this work, the nonrandom lattice fluid equation of state with hydrogen bonding (NLF-HB EOS) was applied for the prediction of phase equilibrium of mixtures containing water and carbon dioxide. A new set of pure component parameters for carbon dioxide above critical condition was found and optimum binary interaction parameters were reported to correlate mutual solubility of mixtures. The calculated results were compared with the Peng-Robinson Equation of State with the conventional mixing rule (PR-EOS) and the Wong-Sandler mixing rule (PR-WS-EOS). The calculation results show that NLF-HB EOS can correlate mutual solubility of water+carbon dioxide mixtures with reasonable accuracy within a single theoretical framework.

In a previous paper [J.N. Jaubert, F. Mutelet, Fluid Phase Equilib. 224 (2004) 285–304], we started to develop a group contribution method aimed at estimating the temperature dependent binary interaction parameters (kij(T)) for the widely... more

In a previous paper [J.N. Jaubert, F. Mutelet, Fluid Phase Equilib. 224 (2004) 285–304], we started to develop a group contribution method aimed at estimating the temperature dependent binary interaction parameters (kij(T)) for the widely used Peng–Robinson equation of state (EOS). In this approach, the kij between two components i and j is a function of temperature (T) and of the pure component critical temperatures (Tci and Tcj), critical pressures (Pci, Pcj) and acentric factors (ωi, ωj). Because our model relies on the Peng–Robinson EOS as published by Peng and Robinson in 1978 and because the addition of a group contribution method to estimate the kij makes it predictive, this model was called PPR78 (predictive 1978, Peng–Robinson EOS). In our previous paper, six groups were defined: CH3, CH2, CH, C, CH4 (methane) and C2H6 (ethane). It was thus possible to estimate the kij for any mixture of saturated hydrocarbons (n-alkanes and branched alkanes), whatever the temperature. In this study, the PPR78 model is extended to systems containing aromatic compounds. To do so, two new groups were added: CHaro and Caro.

The phase equilibrium and thermodynamic information of the CaO-MgO-SiO2 system at 1 atm was reviewed and assessed by using thermodynamic models for the Gibbs energy of all the phases. The assessment was based on recent assessments of the... more

The phase equilibrium and thermodynamic information of the CaO-MgO-SiO2 system at 1 atm was reviewed and assessed by using thermodynamic models for the Gibbs energy of all the phases. The assessment was based on recent assessments of the CaO-MgO, CaO-SiO2, and MgO-SiO2 systems. Two thermodynamic models were used: the two-sublattice model for ionic liquids for the liquid phase, and the compound energy model for the solid solution phases. The model parameters were evaluated by fitting to the selected experimental data by means of a computer program, which can accommodate a variety of experimental data. A consistent set of parameters was obtained that sat-isfactorily described most of the experimental information. The models were found to be well-suited for the present system, and only a small number of adjustable parameters were needed. Extensive comparisons were made between the calculations and experimental data.

The crystal structures of the tungsten monocarbide δ-WC and the disordered lower carbide β-W2C are studied. Using magnetic susceptibility measurements, the hexagonal carbide δ-WC is shown to be stable from 300 to 1200 K. The sequence of... more

The crystal structures of the tungsten monocarbide δ-WC and the disordered lower carbide β-W2C are studied. Using magnetic susceptibility measurements, the hexagonal carbide δ-WC is shown to be stable from 300 to 1200 K. The sequence of phase transformations associated with β-W2C ordering is analyzed. The temperature and composition stability limits of the cubic carbide γ-WC1−x are evaluated, and the first data are presented on the variation of its lattice parameter with composition. An optimized W-C phase diagram is proposed which takes into account detailed structural and phase-equilibrium data for tungsten carbides.