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Chau-chyun Chen - One of the best experts on this subject based on the ideXlab platform.
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Local composition Activity Coefficient model for mixed-gas adsorption equilibria
Adsorption, 2019Co-Authors: Harnoor Kaur, Hla Tun, Michael Sees, Chau-chyun ChenAbstract:Taking into consideration the adsorbate–adsorbent interactions, a novel Activity Coefficient model is derived from the non-random two-liquid theory for mixed-gas adsorption equilibria. In contrast with the conventional Activity Coefficient models developed for bulk liquids, the new model correctly predicts negative deviations from ideality for adsorbed phase mixtures including azeotropic behavior exhibited by selected gas-adsorbent systems. Requiring a single binary interaction parameter per adsorbate–adsorbate pair, the model successfully correlates wide varieties of binary adsorption isotherm data and it should be a powerful engineering thermodynamic tool in correlating and predicting mixed-gas adsorption equilibria.
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symmetric electrolyte nonrandom two liquid Activity Coefficient model
Industrial & Engineering Chemistry Research, 2009Co-Authors: Yuhua Song, Chau-chyun ChenAbstract:The electrolyte nonrandom two-liquid (eNRTL) model is reformulated as a symmetric Activity Coefficient model with the reference states chosen to be pure liquids for solvents and pure fused salts for electrolytes. These reference states are consistently used in the local interaction term, represented by a reformulated NRTL expression, and the long-range interaction term, represented by an extended symmetric Pitzer−Debye−Huckel expression. Retaining the local electroneutrality and like-ion repulsion hypotheses, the new symmetric electrolyte NRTL model yields simpler Activity Coefficient expressions for both molecular and ionic species. The utility of the model is demonstrated with vapor−liquid equilibrium, liquid−liquid equilibrium, and solid−liquid equilibria of several mixed solvent electrolyte systems.
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correlation and prediction of phase behavior of organic compounds in ionic liquids using the nonrandom two liquid segment Activity Coefficient model
Industrial & Engineering Chemistry Research, 2008Co-Authors: Chau-chyun Chen, Luke D Simoni, Joan F Brennecke, Mark A StadtherrAbstract:Room-temperature ionic liquids have shown great potential as media for reactions and separations. Information on how organic compounds interact with these ionic liquids is crucial in assessing their usefulness. Here, the nonrandom two-liquid segment Activity Coefficient (NRTL-SAC) model is used first to correlate values of infinite-dilution Activity Coefficients for organic compounds in ionic liquids and then to predict the phase behavior of various mixtures involving these ionic liquids. NRTL-SAC provides a robust, qualitative predictive model based on four molecular descriptors that are designed to capture molecular surface interaction characteristics: hydrophobicity, hydrophilicity, polarity, and solvation strength.
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refined electrolyte nrtl model Activity Coefficient expressions for application to multi electrolyte systems
Aiche Journal, 2008Co-Authors: George M Bollas, Chau-chyun Chen, Paul I BartonAbstract:The influence of simplifying assumptions of the electrolyte-nonrandom two-liquid (NRTL) model in the derivation of Activity Coefficient expressions as applied to multi-electrolyte systems is critically examined. A rigorous and thermodynamically consistent formulation for the Activity Coefficients is developed, in which the simplifying assumption of holding ionic-charge fraction quantities constant in the derivation of Activity Coefficient expressions is removed. The refined Activity Coefficient formulation possesses stronger theoretical properties and practical superiority that is demonstrated through a case study representing the thermodynamic properties and speciation of dilute to concentrated aqueous sulfuric acid solutions at ambient conditions. In this case study phenomena, such as hydration, ion pairing, and partial dissociation are all taken into account. The overall result of this study is a consistent, analytically derived, short-range interaction contribution formulation for the electrolyte-NRTL Activity Coefficients and a very accurate representation of aqueous sulfuric acid solutions at ambient conditions at concentrations up to 50 molal. © 2008 American Institute of Chemical Engineers AIChE J, 2008
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correlation and prediction of drug molecule solubility in mixed solvent systems with the nonrandom two liquid segment Activity Coefficient nrtl sac model
Industrial & Engineering Chemistry Research, 2006Co-Authors: Chau-chyun Chen, Peter A CraftsAbstract:The recently developed Nonrandom Two-Liquid Segment Activity Coefficient (NRTL−SAC) model [reported by Chen and Song, Ind. Eng. Chem. Res. 2004, 43, 8354] offers a practical thermodynamic framework to predict drug solubility in a wide range of solvents, based on a small initial set of measured solubility data. The model yields satisfactory results in first correlating drug solubility in a few representative pure solvents and then qualitatively predicting drug solubility in other pure solvents. Here, we investigate the applicability of the NRTL−SAC model for predicting drug solubility in mixed solvents for three molecules: acetaminophen, sulfadiazine, and cimetidine. The study shows that the model provides robust correlation and prediction of drug solubility in both pure and mixed solvents, with a qualitative level of accuracy. The model is a useful tool in support of the early stages of crystallization process development and other areas of drug process design.
Shiang-tai Lin - One of the best experts on this subject based on the ideXlab platform.
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Explicit consideration of spatial hydrogen bonding direction for Activity Coefficient prediction based on implicit solvation calculations
Physical chemistry chemical physics : PCCP, 2017Co-Authors: Wei-lin Chen, Shiang-tai LinAbstract:The Activity Coefficient of a chemical in a mixture is important in understanding the thermodynamic properties and non-ideality of the mixture. The COSMO-SAC model based on the result of quantum mechanical implicit solvation calculations has been shown to provide reliable predictions of Activity Coefficients for mixed fluids. However, it is found that the prediction accuracy is in general inferior for associating fluids. Existing methods for describing the hydrogen-bonding interaction consider the strength of the interaction based only on the polarity of the screening charges, neglecting the fact that the formation of hydrogen bonds requires a specific orientation between the donor and acceptor pairs. In this work, we propose a new approach that takes into account the spatial orientational constraints in hydrogen bonds. Based on the Valence Shell Electron Pair Repulsion (VSEPR) theory, the molecular surfaces associated with the formation of hydrogen bonds are limited to those in the projection of the lone pair electrons of hydrogen bond acceptors, in addition to the polarity of the surface screening charges. Our results show that this new directional hydrogen bond approach, denoted as the COSMO-SAC(DHB) model, requires fewer universal parameters and is significantly more accurate and reliable compared to previous models for a variety of properties, including vapor-liquid equilibria (VLE), infinite dilution Activity Coefficient (IDAC) and water-octanol partition Coefficient (Kow).
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prediction of phase behaviors of polymer solvent mixtures from the cosmo sac Activity Coefficient model
Industrial & Engineering Chemistry Research, 2013Co-Authors: Yuching Kuo, Chanchia Hsu, Shiang-tai LinAbstract:An efficient method for prediction of the vapor–liquid and liquid–liquid phase behaviors of polymer–solvent mixtures is proposed using the COSMO-SAC Activity Coefficient model. In particular, we examine various approaches for generating the screening charge distribution of homepolymers and copolymers from quantum mechanical calculations and propose a novel method to generate such data efficiently using a finite number of repeating units. The free volume effects known to be important in polymer solutions are considered through the free volume model of Elbro and co-workers. We have examined this model using 2249 vapor–liquid equilibria data points from 25 homopolymers, 8 copolymers, and 48 solvents. The overall average deviation (AAD%) of solvent Activity is found to be about 16%, which is comparable to that from other UNIFAC-based models. The liquid–liquid equilibrium of polymer–solvent mixtures can be predicted in qualitative agreement with experiment. The proposed method is capable of describing the chan...
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towards the development of theoretically correct liquid Activity Coefficient models
The Journal of Chemical Thermodynamics, 2009Co-Authors: Shiang-tai Lin, Minkang Hsieh, Chiehming Hsieh, Chanchia HsuAbstract:Abstract We propose a general approach for developing liquid Activity Coefficient models based on the concept of local composition that satisfy at least two important physical conditions: (1) the total number of neighboring molecules around one molecule of species A must be a constant at any temperature for all possible mixture compositions, and (2) the number of pairs between any two species A – B determined from the local composition of B around A must be the same as that of A around B. Most commonly used liquid Activity Coefficient models (such as UNIQUAC) satisfy condition (1) but fail to meet condition (2), and thus are considered as fundamentally flawed. We propose a general formulation for the local composition equation containing a symmetric function of species A and B which ensures condition (2) be always satisfied. We show that the composition and temperature dependence of the symmetric functions can be completely obtained from condition (1), resulting in a new class of excess Gibbs free energy models. It is found that such a model can quantitatively reproduce the results of Monte Carlo simulation for various types of lattice fluids, while conventional models are merely qualitative. Furthermore, such a model is more accurate than the UNIQUAC model in correlating experimental data, especially in the dilute regime. Therefore, models developed based on this approach are theoretically sound and potentially applicable to a broader range of conditions.
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prediction of mixture vapor liquid equilibrium from the combined use of peng robinson equation of state and cosmo sac Activity Coefficient model through the wong sandler mixing rule
Fluid Phase Equilibria, 2007Co-Authors: Mingtsung Lee, Shiang-tai LinAbstract:Abstract In this work we examined the prediction of vapor–liquid equilibria (VLE) of mixtures from the combined use of the Peng–Robinson equation of state (PR EOS) and the COSMO-SAC liquid Activity Coefficient model (LM). Based on the results of quantum mechanical calculations, it has been shown that the COSMO-SAC model is capable of predicting VLE of mixtures away from the critical point of any constituent component. Following the Wong–Sandler mixing rule, we found that the combined model is capable of predicting the VLE of binary mixtures, including alkane and alkane, alkane and alcohol, alkane and ketone, and alcohol and water, over a wide range of temperature (183.15–623.15 K) and pressure (0.1–19 MPa). Furthermore, it is found that the accuracy can be greatly improved when the Stavermann–Guggenheim combinatorial term in the COSMO-SAC model is ignored. The average error in both the pressure and vapor phase composition from the latter approach, denoted as PR + WS + COSMOSACres, is lowered by more than 50% compared to that from the PR EOS with the van der Waals one fluid mixing rule (PR + VDW). Our results show that PR + WS + COSMOSACres is a promising approach for mixture VLE predictions over a large range of conditions.
Yuhua Song - One of the best experts on this subject based on the ideXlab platform.
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symmetric electrolyte nonrandom two liquid Activity Coefficient model
Industrial & Engineering Chemistry Research, 2009Co-Authors: Yuhua Song, Chau-chyun ChenAbstract:The electrolyte nonrandom two-liquid (eNRTL) model is reformulated as a symmetric Activity Coefficient model with the reference states chosen to be pure liquids for solvents and pure fused salts for electrolytes. These reference states are consistently used in the local interaction term, represented by a reformulated NRTL expression, and the long-range interaction term, represented by an extended symmetric Pitzer−Debye−Huckel expression. Retaining the local electroneutrality and like-ion repulsion hypotheses, the new symmetric electrolyte NRTL model yields simpler Activity Coefficient expressions for both molecular and ionic species. The utility of the model is demonstrated with vapor−liquid equilibrium, liquid−liquid equilibrium, and solid−liquid equilibria of several mixed solvent electrolyte systems.
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extension of nonrandom two liquid segment Activity Coefficient model for electrolytes
Industrial & Engineering Chemistry Research, 2005Co-Authors: Chauchyun Chen And, Yuhua SongAbstract:The nonrandom two-liquid segment Activity Coefficient model of Chen and Song (Ind. Eng. Chem. Res. 2004, 43, 8354) has shown to be a simple and practical tool for chemists and engineers to correlate and estimate solubilities of organic nonelectrolytes in support of chemical and pharmaceutical process design. In this paper, the model is extended for the computation of ionic Activity Coefficients and solubilities of electrolytes, organic and inorganic, in common solvents and solvent mixtures. In addition to the three types of molecular parameters defined for organic nonelectrolytes, i.e., hydrophobicity X, polarity Y, and hydrophilicity Z, an electrolyte parameter, E, is introduced to characterize both local and long-range ion−ion and ion−molecule interactions attributed to ionized segments of electrolytes. Successful representations of mean ionic Activity Coefficients and solubilities of electrolytes, inorganic and organic, in aqueous and nonaqueous solvents are presented.
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solubility modeling with a nonrandom two liquid segment Activity Coefficient model
Industrial & Engineering Chemistry Research, 2004Co-Authors: Chau-chyun Chen, Yuhua SongAbstract:A segment contribution Activity Coefficient model, derived from the polymer nonrandom two-liquid model, is proposed for fast, qualitative estimation of the solubilities of organic nonelectrolytes in common solvents. Conceptually, the approach suggests that one account for the liquid nonideality of mixtures of complex pharmaceutical molecules and small solvent molecules in terms of interactions between three pairwise interacting conceptual segments: hydrophobic segment, hydrophilic segment, and polar segment. In practice, these conceptual segments become the molecular descriptors used to represent the molecular surface characteristics of each solute and solvent molecule. The treatment results in component-specific molecular parameters: hydrophobicity X, polarity Y, and hydrophilicity Z. Once the molecular parameters are identified from experimental data for common solvents and solute molecules, the model offers a simple and practical thermodynamic framework to estimate solubilities and to perform other p...
Peter A Crafts - One of the best experts on this subject based on the ideXlab platform.
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correlation and prediction of drug molecule solubility in mixed solvent systems with the nonrandom two liquid segment Activity Coefficient nrtl sac model
Industrial & Engineering Chemistry Research, 2006Co-Authors: Chau-chyun Chen, Peter A CraftsAbstract:The recently developed Nonrandom Two-Liquid Segment Activity Coefficient (NRTL−SAC) model [reported by Chen and Song, Ind. Eng. Chem. Res. 2004, 43, 8354] offers a practical thermodynamic framework to predict drug solubility in a wide range of solvents, based on a small initial set of measured solubility data. The model yields satisfactory results in first correlating drug solubility in a few representative pure solvents and then qualitatively predicting drug solubility in other pure solvents. Here, we investigate the applicability of the NRTL−SAC model for predicting drug solubility in mixed solvents for three molecules: acetaminophen, sulfadiazine, and cimetidine. The study shows that the model provides robust correlation and prediction of drug solubility in both pure and mixed solvents, with a qualitative level of accuracy. The model is a useful tool in support of the early stages of crystallization process development and other areas of drug process design.
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correlation and prediction of drug molecule solubility in mixed solvent systems with the nonrandom two liquid segment Activity Coefficient nrtl sac model
Industrial & Engineering Chemistry Research, 2006Co-Authors: Chau-chyun Chen, Peter A CraftsAbstract:The recently developed Nonrandom Two-Liquid Segment Activity Coefficient (NRTL−SAC) model [reported by Chen and Song, Ind. Eng. Chem. Res. 2004, 43, 8354] offers a practical thermodynamic framework to predict drug solubility in a wide range of solvents, based on a small initial set of measured solubility data. The model yields satisfactory results in first correlating drug solubility in a few representative pure solvents and then qualitatively predicting drug solubility in other pure solvents. Here, we investigate the applicability of the NRTL−SAC model for predicting drug solubility in mixed solvents for three molecules: acetaminophen, sulfadiazine, and cimetidine. The study shows that the model provides robust correlation and prediction of drug solubility in both pure and mixed solvents, with a qualitative level of accuracy. The model is a useful tool in support of the early stages of crystallization process development and other areas of drug process design.
Yusuke Shimoyama - One of the best experts on this subject based on the ideXlab platform.
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effect of mixing rule and Activity Coefficient model on prediction of solid liquid gas equilibria for carbon dioxide organic compound mixtures using peng robinson equation of state and ge type mixing rule
Fluid Phase Equilibria, 2013Co-Authors: Yusuke ShimoyamaAbstract:Abstract Solid–liquid–gas equilibria (SLGE) for carbon dioxide + organic compound mixtures were predicted by Peng–Robinson (PR) equation of state with excess Gibbs free energy (GE) type mixing rule. Activity Coefficient models using molecular surface charge density were applied for the calculation of Activity Coefficient and GE in the mixing rules. Two types of GE type mixing rule, Modified Huron–Vidal (MHV1) and Linear Combination of Vidal and Michelsen (LCVM) mixing rules were applied for the energy and size parameters on PR equation of state. The Activity Coefficient models used in this work were Conductor-like Screening Model Segment Activity Coefficient (COSMO-SAC) and COSMO-UNIQUAC. In these Activity Coefficient models, two kinds of the combinatorial equations, Stavermann–Guggenheim (SG) and Flory–Huggins (FH) equations were used. Consequently, the eight combinations with the GE type mixing rule, the Activity Coefficient model and the combinatorial equation were applied for the prediction of SLGE for carbon dioxide + organic compound mixtures. The organic compounds interested in this work were aromatic hydrocarbons, alcohols and acids. On the SLVE calculation in this work, the temperatures at the phase equilibria were calculated by fixed pressure. The effects of mixing rule and Activity Coefficient model on the prediction performance of the solid–liquid–gas equilibria were investigated. The combination of MHV1/COSMO-SAC/SG presented the best performance of the SLVE prediction for carbon dioxide + aromatic hydrocarbon systems. The absolute deviation between experimental and predicted result of the temperature at the SLGE was 3.6 K in temperature. For alcohols and acids, the smallest absolute deviations between experimental and predicted results of the temperature at the SLGE were given by the combinations of MHV1/COSMO-SAC/FH and LCVM/COSMO-SAC/FH, respectively. The values of the absolute deviations were 1.1 and 4.1 K for alcohols and acids.
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predictions of cation and anion effects on solubilities selectivities and permeabilities for co2 in ionic liquid using cosmo based Activity Coefficient model
Fluid Phase Equilibria, 2010Co-Authors: Yusuke Shimoyama, Akira ItoAbstract:Abstract The solubilities and selectivities for CO 2 , N 2 and CH 4 in ionic liquid were predicted using a COSMO based Activity Coefficient model, COSMO-SAC method. The 1-alkyl-3-methylimidazolium cations were focused in this work. The anion species include tetrafluoroborate [BF 4 ], hexafluorophosphate [PF 6 ], triflate [OTf], dicyanamide [dca] and bis(trifluoromethane)-sulfonimide [Tf 2 N]. The predicted results of the solubilities of CO 2 in the ionic liquids by COSMO-SAC method are in agreement with the experimental data within the averaged deviation of 0.0017 in mole fraction. The predicted results of selectivities for CO 2 /N 2 and CO 2 /CH 4 represent the effects of anion species qualitatively. Permeability through supported liquid membrane can be presented by solubility and diffusion Coefficients in the liquid. The permeabilities of CO 2 through the ionic liquid membranes were also predicted by a solution-diffusion model with COSMO-SAC method. The predicted results of the CO 2 permeabilities through the ionic liquids represent the experimental data within the order of the permeabilities.
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development of Activity Coefficient model based on cosmo method for prediction of solubilities of solid solutes in supercritical carbon dioxide
Journal of Supercritical Fluids, 2009Co-Authors: Yusuke Shimoyama, Yoshio IwaiAbstract:Abstract A COSMO base Activity Coefficient model was newly developed to predict the solubilities of solid solutes in supercritical carbon dioxide. This Activity Coefficient model describes that the system is composed of the surface segments on the solvent molecule and vacancy unlike the conventional model based on COSMO method. The density change of supercritical fluid can be represented by the change of the surface area of the vacancy. This prediction model is referred to “COSMO-vac (vacancy)” model. The solubilities of 16 pharmaceuticals in supercritical carbon dioxide were predicted by COSMO-vac model. The averaged deviations between the logarithmic experimental and predicted results are smaller than unity. Furthermore, the predicted results for the solutes composed of only C, H and O atoms are better than those for the solutes including the other atoms. The percentage of the predicted results within the order of the experimental data at the pressure over 15 MPa is higher than that at the pressures below 15 MPa.
