M. Olaya - Academia.edu (original) (raw)

Papers by M. Olaya

Research paper thumbnail of Comments on “Analysis of the Nonrandom Two-Liquid Model for Prediction of Liquid–Liquid Equilibria”

Journal of Chemical & Engineering Data, 2015

Research paper thumbnail of Solid−Liquid Equilibrium Thermodynamics:  Checking Stability in Multiphase Systems Using the Gibbs Energy Function

Industrial & Engineering Chemistry Research, 2001

ABSTRACT A new procedure has been suggested and applied to the simultaneous correlation of the ex... more ABSTRACT A new procedure has been suggested and applied to the simultaneous correlation of the experimental data corresponding to all equilibrium regions in ternary systems involving a solid compound. The analysis of the form of the Gibbs energy function permits the validity of the parameters calculated with any particular model to be verified and can be used as a consistence criterion.

Research paper thumbnail of Comments on the problematic nature of the calculation of solid-liquid equilibrium

Fluid Phase Equilibria, 1997

The problematic nature of the calculation of phase equilibria involving solid components is discu... more The problematic nature of the calculation of phase equilibria involving solid components is discussed. The concept of 'the stability criterion', as introduced, accounts for the necessity of a suitable set of parameters for any given activity coefficient model, yielding an appropriate shape of the Gibbs energy function in the whole domain of the equilibrium diagram. The use of a unique reference state (pure liquid at the temperature and pressure of the system), for both solid and liquid phases, is another fact that must be remembered when correlating and predicting these types of equilibria.

Research paper thumbnail of Diseño de un nuevo entorno basado en las TIC para el aprendizaje integral de materias científico-técnicas. Aplicación a la asignatura “Fundamentos de Operaciones …

Research paper thumbnail of Solubilities of nonvolatile solutes in polymers from molecular thermodynamics

Aiche Journal, 2001

ABSTRACT

Research paper thumbnail of DSC and TGA study of the transitions involved in the thermal treatment of binary mixtures of PE and EVA copolymer with a crosslinking agent

Polymer, 2006

The crosslinking process of PE and EVA with different concentrations of a crosslinking agent (CA)... more The crosslinking process of PE and EVA with different concentrations of a crosslinking agent (CA) has been studied. The extent of the crosslinking has been evaluated by gel fraction and density measurements. The different transitions involved in the thermal processing and decomposition have been studied by DSC and TGA and compared for all the mixtures prepared. Mechanistic pseudo-kinetic models have been suggested and applied involving all the fractions susceptible of undergoing transitions or reactions. The models applied can be of great interest in understanding the phenomena involved, as well as in modeling the heat effects in the whole processing or pyrolysis of this type of products. (J.A. Reyes-Labarta), antonio.marcilla@ ua.es (A. Marcilla). 0032-3861/$ -see front matter Ó

Research paper thumbnail of Salt Effect in the Quaternary System Water + Ethanol + 1-Butanol + Potassium Chloride at 25 °C

Journal of Chemical & Engineering Data, 1997

Research paper thumbnail of Distribution coefficients and diffusivities in three polymers for nineteen aqueous nonvolatile solutes

Journal of Applied Polymer Science, 2002

Experimental results at 25°C are reported for infinite-dilution distribution coefficients for 19 ... more Experimental results at 25°C are reported for infinite-dilution distribution coefficients for 19 nonvolatile solutes between aqueous solution and three kinds of polymer films, and for their diffusion coefficients in the polymer matrix. The experiments were performed by coupling UV spectroscopy and gravimetric measurements with mass balances. The solutes are aromatic nonvolatile compounds that are of interest in environmental technology and may serve as model compounds for drugdelivery systems. The polymers are ethylene-vinyl acetate copolymers with 33 (EVAc33) and 45 (EVAc45) weight percentage vinyl acetate, and poly(vinyl acetate) (PVAc) widely used in drug-delivery devices. For PVAc, a long time is required to reach equilibrium. Because the required time is too long for reasonable experimental studies, equilibrium distribution coefficients were calculated from finite-time data by using a diffusion model. The contribution of surface adsorption is shown to be negligible. Infinite-dilution distribution coefficients K s , defined as the volume fraction of solute in the polymer divided by that in water, tend to increase with vinyl acetate content; they range from near unity to several hundred. Diffusion coefficients, determined from time-dependent sorption data, are significantly larger in EVAc copolymers (10 Ϫ10 to 10 Ϫ8 cm 2 /s) than in PVAc (10 Ϫ12 cm 2 /s). These data may be useful for design of membrane processes, for controlled delivery of drugs, and for application in packaging and storage of food, chemicals, and pharmaceuticals.

Research paper thumbnail of DSC study of transitions involved in thermal treatment of foamable mixtures of PE and EVA copolymer with azodicarbonamide

Journal of Applied Polymer Science, 2006

The transitions and reactions involved in the thermal processing of binary mixtures of polyethyle... more The transitions and reactions involved in the thermal processing of binary mixtures of polyethylene and poly(ethylene-co-vinyl acetate) copolymers with different concentrations of a foaming agent (azodicarbonamide) were studied using differential scanning calorimetry (DSC). The effect of ZnO as a kicker also was discussed. The temperature at the maximum rate and the heat evolved were measured for all the processes-melt-ing, transitions, and reactions-all the mixtures prepared were measured and compared. Azodicarbonamide decomposed differently depending on the polymeric matrix. These data can be very useful for the plastic processing industry.

Research paper thumbnail of Approximate Calculation of Distillation Boundaries for Ternary Azeotropic Systems

Industrial & Engineering Chemistry Research, 2011

ABSTRACT As it is very well known, especially when dealing with the simulation and design of dist... more ABSTRACT As it is very well known, especially when dealing with the simulation and design of distillation processes and columns, it is essential to know the limitations defined by the vapor–liquid equilibrium (VLE) of the system under consideration. This paper uses a new straightforward algorithm to calculate and completely define the distillation boundaries in different ternary azeotropic systems. The method allows, using cubic splines, the calculation of different distillation trajectories and the selection of those corresponding to the searched distillation boundaries. The algorithm has been applied to eight ternary liquid–vapor systems to test its validity. To simplify the optimization process, an empirical but very accurate equation has been used to calculate the VLE.

Research paper thumbnail of Aspects To Be Considered for the Development of a Correlation Algorithm for Condensed Phase Equilibrium Data of Ternary Systems

Industrial & Engineering Chemistry Research, 2010

ABSTRACT The existing commercial software packages for equilibrium data correlation, or analogous... more ABSTRACT The existing commercial software packages for equilibrium data correlation, or analogous tools included in chemical process simulators, have been widely used and their extensive capabilities are well-known. Nevertheless, and as far as LLE calculations are concerned, they have been designed for the simplest equilibrium behavior. For example, for ternary systems, only the correlation of type 1 and type 2 LLE data is possible. None of these applications allows for the correlation of type 0 LLE, type 3 LLLE, or type 4 LLSE systems, although these are interesting for many industrial purposes. To enable a possible extension of such software, a robust computation algorithm has been developed to correlate phase equilibrium data among condensed phases for all of these more complicated behaviors. Moreover, this algorithm includes some new strategies to avoid the main problems occurring through correlation procedures, which lead to convergence problems or inconsistent results. These strategies are explained in detail in the present work.

Research paper thumbnail of Liquid−Vapor Equilibrium Data Correlation: Part I. Pitfalls and Some Ideas to Overcome Them

Industrial & Engineering Chemistry Research, 2011

ABSTRACT Accurate description of VLE (and VLLE) plays an essential role in many industrial separa... more ABSTRACT Accurate description of VLE (and VLLE) plays an essential role in many industrial separation processes. Local composition models for the activity coefficient description, such as NRTL and UNIQUAC, have contributed significantly over the past four decades toward the fitting of experimental VLE data, for example, to the design of distillation towers. However, a critical examination of this field reveals that important deficiencies still exist due to the complex nature of the topic. In the present paper, these pitfalls are classified and discussed in detail, and some examples are selected to conveniently illustrate every one of them. We also comment on some aspects that could improve the distribution, evaluation and correlation of these VLE (and VLLE) data that, in turn, could lead to better results and avoid misinterpretations.

Research paper thumbnail of New Method for Quaternary Systems Liquid−Liquid Extraction Tray to Tray Design

Industrial & Engineering Chemistry Research, 1999

Research paper thumbnail of Solid−Liquid Equilibrium Thermodynamics:  Checking Stability in Multiphase Systems Using the Gibbs Energy Function

Industrial & Engineering Chemistry Research, 2001

ABSTRACT A new procedure has been suggested and applied to the simultaneous correlation of the ex... more ABSTRACT A new procedure has been suggested and applied to the simultaneous correlation of the experimental data corresponding to all equilibrium regions in ternary systems involving a solid compound. The analysis of the form of the Gibbs energy function permits the validity of the parameters calculated with any particular model to be verified and can be used as a consistence criterion.

Research paper thumbnail of Simultaneous Correlation of Liquid−Liquid, Liquid−Solid, and Liquid−Liquid−Solid Equilibrium Data for Water + Organic Solvent + Salt Ternary Systems. Anhydrous Solid Phase

Industrial & Engineering Chemistry Research, 2007

ABSTRACT The simultaneous correlation of liquid−liquid (LL), liquid−solid (LS), and LLS equilibri... more ABSTRACT The simultaneous correlation of liquid−liquid (LL), liquid−solid (LS), and LLS equilibrium data for four water + organic solvent (alcohol or acetone) + inorganic salt (NaCl) ternary systems at 25 °C has been carried out. First, the NRTL equation was used to formulate the excess Gibbs energy (GE), assuming nondissociation of the dissolved salt in the liquid phase. Afterward, a modification of the NRTL equation taking into account the ionic behavior of the solid (electrolyte-NRTL) was introduced into the simultaneous correlation of the equilibrium regions for the same systems. The binary parameters and the comparison of the experimental and calculated equilibrium data obtained with both the molecular and electrolyte models are presented in this work. The stability analysis based on the Gibbs energy function of mixing, together with the common tangent criteria have been used to validate the parameters calculated.

Research paper thumbnail of Checking Liquid–Liquid Plait Point Conditions and Their Application in Ternary Systems

Industrial & Engineering Chemistry Research, 2012

ABSTRACT This work reviews the thermodynamic criteria for incipient immiscibility at the plait po... more ABSTRACT This work reviews the thermodynamic criteria for incipient immiscibility at the plait point in ternary systems, and also shows its application to singular LL equilibria, such as different type 3 ternary systems (Treybal classification), where an inadequate use of the criteria could yield to ambiguities.

Research paper thumbnail of Methods for improving models for condensed phase equilibrium calculations

Fluid Phase Equilibria, 2010

Local composition models like UNIQUAC, NRTL and the UNIFAC group contribution method are used the... more Local composition models like UNIQUAC, NRTL and the UNIFAC group contribution method are used the world over in the synthesis and design of separation processes, as well as for a large number of other applications of industrial interest. They can qualitatively describe the equilibrium behaviour of systems of different complexities but, sometimes, not with the precision required for the design of separation equipment. Regrettably, this precision is not even achieved for the LLE of many conventional type 1 and some type 2 ternary systems. High deviations in correlation results are not rare, thus showing that more capable and flexible models are needed. The analysis of the topology of the Gibbs energy of mixing function, and therefore the knowledge of the geometrical conditions that this function has to fulfil, is a valuable tool that has allowed avoiding inconsistencies in the use of the existing methods, to ascertain their capabilities and limitations to reproduce complex systems and additionally to suggest new models that improve the flexibility and accuracy needed. In this work, a simple equation based on the NRTL model, that takes into account such topological conditions, is proposed and its capabilities are tested with selected systems.

Research paper thumbnail of Correlation of the liquid–liquid equilibrium data for specific ternary systems with one or two partially miscible binary subsystems

Fluid Phase Equilibria, 2009

This paper presents the results of a liquid–liquid equilibrium data correlation for 11 ternary sy... more This paper presents the results of a liquid–liquid equilibrium data correlation for 11 ternary systems which have not been previously fitted using the NRTL model or, when they have, the results presented in the literature are inconsistent with the experimental behavior of the system. These ternary systems include mixtures with one or two partially miscible pairs. During the correlation process,

Research paper thumbnail of Gibbs energy based procedure for the correlation of type 3 ternary systems including a three-liquid phase region

Fluid Phase Equilibria, 2009

Equilibrium data for type 3 ternary systems comprising a liquid-liquid-liquid equilibrium region ... more Equilibrium data for type 3 ternary systems comprising a liquid-liquid-liquid equilibrium region (LLLE tie-triangle) are not frequently correlated, as is evidenced by a lack of studies in the literature. In the present paper, a robust algorithm to calculate or correlate equilibrium data for this type of system is proposed. This algorithm is based on geometric aspects related to the Gibbs energy of mixing (g M ) and possesses some interesting advantages that are discussed in the text. The methodology put forward is applied to correlate the equilibrium data of three type 3 ternary systems. The NRTL model is used to define g M , and the common tangent plane criterion to define the equilibrium condition for the calculations. The lack in flexibility of the NRTL equation to model these systems is discussed.

Research paper thumbnail of Modelling liquid–liquid equilibria for island type ternary systems

Fluid Phase Equilibria, 2008

miscibility gaps in ternary liquid mixtures are obtained if phase separations occurs only in the ... more miscibility gaps in ternary liquid mixtures are obtained if phase separations occurs only in the ternary region whilst all binary systems are comp le. Despite this type of ternary systems are not so infrequent, as far as we know there is no information about the applicability of the common equili s, as NRTL and UNIQUAC, for these systems. Also, none of the island systems published in Liquid-Liquid Equilibrium Data Collection, DECH stry Data Series [1], is correlated. In this paper, we study the applicability of the NRTL equation to model the LLE of island type ternary systems.

Research paper thumbnail of Comments on “Analysis of the Nonrandom Two-Liquid Model for Prediction of Liquid–Liquid Equilibria”

Journal of Chemical & Engineering Data, 2015

Research paper thumbnail of Solid−Liquid Equilibrium Thermodynamics:  Checking Stability in Multiphase Systems Using the Gibbs Energy Function

Industrial & Engineering Chemistry Research, 2001

ABSTRACT A new procedure has been suggested and applied to the simultaneous correlation of the ex... more ABSTRACT A new procedure has been suggested and applied to the simultaneous correlation of the experimental data corresponding to all equilibrium regions in ternary systems involving a solid compound. The analysis of the form of the Gibbs energy function permits the validity of the parameters calculated with any particular model to be verified and can be used as a consistence criterion.

Research paper thumbnail of Comments on the problematic nature of the calculation of solid-liquid equilibrium

Fluid Phase Equilibria, 1997

The problematic nature of the calculation of phase equilibria involving solid components is discu... more The problematic nature of the calculation of phase equilibria involving solid components is discussed. The concept of 'the stability criterion', as introduced, accounts for the necessity of a suitable set of parameters for any given activity coefficient model, yielding an appropriate shape of the Gibbs energy function in the whole domain of the equilibrium diagram. The use of a unique reference state (pure liquid at the temperature and pressure of the system), for both solid and liquid phases, is another fact that must be remembered when correlating and predicting these types of equilibria.

Research paper thumbnail of Diseño de un nuevo entorno basado en las TIC para el aprendizaje integral de materias científico-técnicas. Aplicación a la asignatura “Fundamentos de Operaciones …

Research paper thumbnail of Solubilities of nonvolatile solutes in polymers from molecular thermodynamics

Aiche Journal, 2001

ABSTRACT

Research paper thumbnail of DSC and TGA study of the transitions involved in the thermal treatment of binary mixtures of PE and EVA copolymer with a crosslinking agent

Polymer, 2006

The crosslinking process of PE and EVA with different concentrations of a crosslinking agent (CA)... more The crosslinking process of PE and EVA with different concentrations of a crosslinking agent (CA) has been studied. The extent of the crosslinking has been evaluated by gel fraction and density measurements. The different transitions involved in the thermal processing and decomposition have been studied by DSC and TGA and compared for all the mixtures prepared. Mechanistic pseudo-kinetic models have been suggested and applied involving all the fractions susceptible of undergoing transitions or reactions. The models applied can be of great interest in understanding the phenomena involved, as well as in modeling the heat effects in the whole processing or pyrolysis of this type of products. (J.A. Reyes-Labarta), antonio.marcilla@ ua.es (A. Marcilla). 0032-3861/$ -see front matter Ó

Research paper thumbnail of Salt Effect in the Quaternary System Water + Ethanol + 1-Butanol + Potassium Chloride at 25 °C

Journal of Chemical & Engineering Data, 1997

Research paper thumbnail of Distribution coefficients and diffusivities in three polymers for nineteen aqueous nonvolatile solutes

Journal of Applied Polymer Science, 2002

Experimental results at 25°C are reported for infinite-dilution distribution coefficients for 19 ... more Experimental results at 25°C are reported for infinite-dilution distribution coefficients for 19 nonvolatile solutes between aqueous solution and three kinds of polymer films, and for their diffusion coefficients in the polymer matrix. The experiments were performed by coupling UV spectroscopy and gravimetric measurements with mass balances. The solutes are aromatic nonvolatile compounds that are of interest in environmental technology and may serve as model compounds for drugdelivery systems. The polymers are ethylene-vinyl acetate copolymers with 33 (EVAc33) and 45 (EVAc45) weight percentage vinyl acetate, and poly(vinyl acetate) (PVAc) widely used in drug-delivery devices. For PVAc, a long time is required to reach equilibrium. Because the required time is too long for reasonable experimental studies, equilibrium distribution coefficients were calculated from finite-time data by using a diffusion model. The contribution of surface adsorption is shown to be negligible. Infinite-dilution distribution coefficients K s , defined as the volume fraction of solute in the polymer divided by that in water, tend to increase with vinyl acetate content; they range from near unity to several hundred. Diffusion coefficients, determined from time-dependent sorption data, are significantly larger in EVAc copolymers (10 Ϫ10 to 10 Ϫ8 cm 2 /s) than in PVAc (10 Ϫ12 cm 2 /s). These data may be useful for design of membrane processes, for controlled delivery of drugs, and for application in packaging and storage of food, chemicals, and pharmaceuticals.

Research paper thumbnail of DSC study of transitions involved in thermal treatment of foamable mixtures of PE and EVA copolymer with azodicarbonamide

Journal of Applied Polymer Science, 2006

The transitions and reactions involved in the thermal processing of binary mixtures of polyethyle... more The transitions and reactions involved in the thermal processing of binary mixtures of polyethylene and poly(ethylene-co-vinyl acetate) copolymers with different concentrations of a foaming agent (azodicarbonamide) were studied using differential scanning calorimetry (DSC). The effect of ZnO as a kicker also was discussed. The temperature at the maximum rate and the heat evolved were measured for all the processes-melt-ing, transitions, and reactions-all the mixtures prepared were measured and compared. Azodicarbonamide decomposed differently depending on the polymeric matrix. These data can be very useful for the plastic processing industry.

Research paper thumbnail of Approximate Calculation of Distillation Boundaries for Ternary Azeotropic Systems

Industrial & Engineering Chemistry Research, 2011

ABSTRACT As it is very well known, especially when dealing with the simulation and design of dist... more ABSTRACT As it is very well known, especially when dealing with the simulation and design of distillation processes and columns, it is essential to know the limitations defined by the vapor–liquid equilibrium (VLE) of the system under consideration. This paper uses a new straightforward algorithm to calculate and completely define the distillation boundaries in different ternary azeotropic systems. The method allows, using cubic splines, the calculation of different distillation trajectories and the selection of those corresponding to the searched distillation boundaries. The algorithm has been applied to eight ternary liquid–vapor systems to test its validity. To simplify the optimization process, an empirical but very accurate equation has been used to calculate the VLE.

Research paper thumbnail of Aspects To Be Considered for the Development of a Correlation Algorithm for Condensed Phase Equilibrium Data of Ternary Systems

Industrial & Engineering Chemistry Research, 2010

ABSTRACT The existing commercial software packages for equilibrium data correlation, or analogous... more ABSTRACT The existing commercial software packages for equilibrium data correlation, or analogous tools included in chemical process simulators, have been widely used and their extensive capabilities are well-known. Nevertheless, and as far as LLE calculations are concerned, they have been designed for the simplest equilibrium behavior. For example, for ternary systems, only the correlation of type 1 and type 2 LLE data is possible. None of these applications allows for the correlation of type 0 LLE, type 3 LLLE, or type 4 LLSE systems, although these are interesting for many industrial purposes. To enable a possible extension of such software, a robust computation algorithm has been developed to correlate phase equilibrium data among condensed phases for all of these more complicated behaviors. Moreover, this algorithm includes some new strategies to avoid the main problems occurring through correlation procedures, which lead to convergence problems or inconsistent results. These strategies are explained in detail in the present work.

Research paper thumbnail of Liquid−Vapor Equilibrium Data Correlation: Part I. Pitfalls and Some Ideas to Overcome Them

Industrial & Engineering Chemistry Research, 2011

ABSTRACT Accurate description of VLE (and VLLE) plays an essential role in many industrial separa... more ABSTRACT Accurate description of VLE (and VLLE) plays an essential role in many industrial separation processes. Local composition models for the activity coefficient description, such as NRTL and UNIQUAC, have contributed significantly over the past four decades toward the fitting of experimental VLE data, for example, to the design of distillation towers. However, a critical examination of this field reveals that important deficiencies still exist due to the complex nature of the topic. In the present paper, these pitfalls are classified and discussed in detail, and some examples are selected to conveniently illustrate every one of them. We also comment on some aspects that could improve the distribution, evaluation and correlation of these VLE (and VLLE) data that, in turn, could lead to better results and avoid misinterpretations.

Research paper thumbnail of New Method for Quaternary Systems Liquid−Liquid Extraction Tray to Tray Design

Industrial & Engineering Chemistry Research, 1999

Research paper thumbnail of Solid−Liquid Equilibrium Thermodynamics:  Checking Stability in Multiphase Systems Using the Gibbs Energy Function

Industrial & Engineering Chemistry Research, 2001

ABSTRACT A new procedure has been suggested and applied to the simultaneous correlation of the ex... more ABSTRACT A new procedure has been suggested and applied to the simultaneous correlation of the experimental data corresponding to all equilibrium regions in ternary systems involving a solid compound. The analysis of the form of the Gibbs energy function permits the validity of the parameters calculated with any particular model to be verified and can be used as a consistence criterion.

Research paper thumbnail of Simultaneous Correlation of Liquid−Liquid, Liquid−Solid, and Liquid−Liquid−Solid Equilibrium Data for Water + Organic Solvent + Salt Ternary Systems. Anhydrous Solid Phase

Industrial & Engineering Chemistry Research, 2007

ABSTRACT The simultaneous correlation of liquid−liquid (LL), liquid−solid (LS), and LLS equilibri... more ABSTRACT The simultaneous correlation of liquid−liquid (LL), liquid−solid (LS), and LLS equilibrium data for four water + organic solvent (alcohol or acetone) + inorganic salt (NaCl) ternary systems at 25 °C has been carried out. First, the NRTL equation was used to formulate the excess Gibbs energy (GE), assuming nondissociation of the dissolved salt in the liquid phase. Afterward, a modification of the NRTL equation taking into account the ionic behavior of the solid (electrolyte-NRTL) was introduced into the simultaneous correlation of the equilibrium regions for the same systems. The binary parameters and the comparison of the experimental and calculated equilibrium data obtained with both the molecular and electrolyte models are presented in this work. The stability analysis based on the Gibbs energy function of mixing, together with the common tangent criteria have been used to validate the parameters calculated.

Research paper thumbnail of Checking Liquid–Liquid Plait Point Conditions and Their Application in Ternary Systems

Industrial & Engineering Chemistry Research, 2012

ABSTRACT This work reviews the thermodynamic criteria for incipient immiscibility at the plait po... more ABSTRACT This work reviews the thermodynamic criteria for incipient immiscibility at the plait point in ternary systems, and also shows its application to singular LL equilibria, such as different type 3 ternary systems (Treybal classification), where an inadequate use of the criteria could yield to ambiguities.

Research paper thumbnail of Methods for improving models for condensed phase equilibrium calculations

Fluid Phase Equilibria, 2010

Local composition models like UNIQUAC, NRTL and the UNIFAC group contribution method are used the... more Local composition models like UNIQUAC, NRTL and the UNIFAC group contribution method are used the world over in the synthesis and design of separation processes, as well as for a large number of other applications of industrial interest. They can qualitatively describe the equilibrium behaviour of systems of different complexities but, sometimes, not with the precision required for the design of separation equipment. Regrettably, this precision is not even achieved for the LLE of many conventional type 1 and some type 2 ternary systems. High deviations in correlation results are not rare, thus showing that more capable and flexible models are needed. The analysis of the topology of the Gibbs energy of mixing function, and therefore the knowledge of the geometrical conditions that this function has to fulfil, is a valuable tool that has allowed avoiding inconsistencies in the use of the existing methods, to ascertain their capabilities and limitations to reproduce complex systems and additionally to suggest new models that improve the flexibility and accuracy needed. In this work, a simple equation based on the NRTL model, that takes into account such topological conditions, is proposed and its capabilities are tested with selected systems.

Research paper thumbnail of Correlation of the liquid–liquid equilibrium data for specific ternary systems with one or two partially miscible binary subsystems

Fluid Phase Equilibria, 2009

This paper presents the results of a liquid–liquid equilibrium data correlation for 11 ternary sy... more This paper presents the results of a liquid–liquid equilibrium data correlation for 11 ternary systems which have not been previously fitted using the NRTL model or, when they have, the results presented in the literature are inconsistent with the experimental behavior of the system. These ternary systems include mixtures with one or two partially miscible pairs. During the correlation process,

Research paper thumbnail of Gibbs energy based procedure for the correlation of type 3 ternary systems including a three-liquid phase region

Fluid Phase Equilibria, 2009

Equilibrium data for type 3 ternary systems comprising a liquid-liquid-liquid equilibrium region ... more Equilibrium data for type 3 ternary systems comprising a liquid-liquid-liquid equilibrium region (LLLE tie-triangle) are not frequently correlated, as is evidenced by a lack of studies in the literature. In the present paper, a robust algorithm to calculate or correlate equilibrium data for this type of system is proposed. This algorithm is based on geometric aspects related to the Gibbs energy of mixing (g M ) and possesses some interesting advantages that are discussed in the text. The methodology put forward is applied to correlate the equilibrium data of three type 3 ternary systems. The NRTL model is used to define g M , and the common tangent plane criterion to define the equilibrium condition for the calculations. The lack in flexibility of the NRTL equation to model these systems is discussed.

Research paper thumbnail of Modelling liquid–liquid equilibria for island type ternary systems

Fluid Phase Equilibria, 2008

miscibility gaps in ternary liquid mixtures are obtained if phase separations occurs only in the ... more miscibility gaps in ternary liquid mixtures are obtained if phase separations occurs only in the ternary region whilst all binary systems are comp le. Despite this type of ternary systems are not so infrequent, as far as we know there is no information about the applicability of the common equili s, as NRTL and UNIQUAC, for these systems. Also, none of the island systems published in Liquid-Liquid Equilibrium Data Collection, DECH stry Data Series [1], is correlated. In this paper, we study the applicability of the NRTL equation to model the LLE of island type ternary systems.