R1270 and R1234ze(E) are environmentally friendly refrigerants with GWP<1 and zero ODP, and the lubricants used in refrigeration system applications need to be matched to the alternative refrigerants and exhibit suitable solubility. In this paper, phase equilibrium studies of R1270 and R1234ze(E) in polyvinyl ether (PVE) lubricants are carried out based on the isovolumetric saturation method. The experimental temperatures ranged from 283.15 to 353.15 K and the pressures ranged from 0 MPa to 2.0 MPa, and the viscosities of the lubricants are determined by viscometers after the solubilisation of the refrigerants, and analysed by molecular dynamics simulations. The microscopic interaction between the refrigerant and the lubricant is analysed by molecular dynamics simulation. The results showed that the solubility of the two refrigerants in PVE68 decreased with increasing temperature, and the solubility of R1270 in PVE68 is smaller than that of R1234ze(E) in PVE68, which is mainly attributed to the strong interactions between fluorine atoms and oxygen atoms during the dissolution process of R1234ze(E) and PVE68. In addition, the viscosity of R1270/PVE68 mixture is lower than that of R1234ze(E)/PVE68 mixture, and the difference in viscosity between the two is smaller; meanwhile, the self-diffusion coefficient D of R1270 is larger than that of R1234ze(E), indicating that the viscosity of the mixture and the self-diffusion coefficient D showed a negative correlation.
{"title":"Experimental study and molecular dynamics modelling of R1270 and R1234ze(E) with polyvinyl ether","authors":"Bujian Zhang, Zhao Yang, Xueling Liu, Hongxia He, Zhaoning Hou, Lei Gao","doi":"10.1016/j.fluid.2025.114634","DOIUrl":"10.1016/j.fluid.2025.114634","url":null,"abstract":"<div><div>R1270 and R1234ze(E) are environmentally friendly refrigerants with GWP<1 and zero ODP, and the lubricants used in refrigeration system applications need to be matched to the alternative refrigerants and exhibit suitable solubility. In this paper, phase equilibrium studies of R1270 and R1234ze(E) in polyvinyl ether (PVE) lubricants are carried out based on the isovolumetric saturation method. The experimental temperatures ranged from 283.15 to 353.15 K and the pressures ranged from 0 MPa to 2.0 MPa, and the viscosities of the lubricants are determined by viscometers after the solubilisation of the refrigerants, and analysed by molecular dynamics simulations. The microscopic interaction between the refrigerant and the lubricant is analysed by molecular dynamics simulation. The results showed that the solubility of the two refrigerants in PVE68 decreased with increasing temperature, and the solubility of R1270 in PVE68 is smaller than that of R1234ze(E) in PVE68, which is mainly attributed to the strong interactions between fluorine atoms and oxygen atoms during the dissolution process of R1234ze(E) and PVE68. In addition, the viscosity of R1270/PVE68 mixture is lower than that of R1234ze(E)/PVE68 mixture, and the difference in viscosity between the two is smaller; meanwhile, the self-diffusion coefficient <em>D</em> of R1270 is larger than that of R1234ze(E), indicating that the viscosity of the mixture and the self-diffusion coefficient <em>D</em> showed a negative correlation.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"603 ","pages":"Article 114634"},"PeriodicalIF":2.7,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145682421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-19DOI: 10.1016/j.fluid.2025.114633
Alessandro Cazonatto Galvão , Amanda Taruhn Mioto , Raquel Bordignon , Igor Gabriel Kaiser , Pedro Felipe Arce , Weber da Silva Robazza
This study explores the solubility of theophylline in binary liquid mixtures of water with methanol, ethanol, or 2-propanol, across all mole fractions and temperatures from 283.2 K to 323.2 K. The composition of the liquid phase was determined using a gravimetric method. Solubility increases with temperature and shows a weak dependence on the solvent mixture’s dielectric constant, driven more by hydrogen bonding. Solubility trends across all isotherms show two patterns: an initial rise with water content, followed by a decline after a solubility peak. This suggests an endothermic dissolution and a hydration effect at specific water levels. This work provides novel solubility data for theophylline in water-ethanol mixtures, absent in the literature, and generates 32 new interaction parameters for UNIFAC-Dortmund and ASOG models. The UNIFAC-Dortmund and ASOG activity coefficient models were fitted to the experimental data, generating new parameters. The UNIFAC-Dortmund parameters were used to predict theophylline solubility with the PSRK equation of state. Model performance was assessed with average relative deviation (ARD), root mean square deviation (RMSD), and Bayesian Information Criterion (BIC). The ASOG showed the best performance, followed by UNIFAC-Dortmund and PSRK.
{"title":"Theophylline solubility in water-alcohol mixtures: Novel experimental data and predictive modeling with UNIFAC-Dortmund, ASOG, and PSRK from 283 K to 323 K","authors":"Alessandro Cazonatto Galvão , Amanda Taruhn Mioto , Raquel Bordignon , Igor Gabriel Kaiser , Pedro Felipe Arce , Weber da Silva Robazza","doi":"10.1016/j.fluid.2025.114633","DOIUrl":"10.1016/j.fluid.2025.114633","url":null,"abstract":"<div><div>This study explores the solubility of theophylline in binary liquid mixtures of water with methanol, ethanol, or 2-propanol, across all mole fractions and temperatures from 283.2 K to 323.2 K. The composition of the liquid phase was determined using a gravimetric method. Solubility increases with temperature and shows a weak dependence on the solvent mixture’s dielectric constant, driven more by hydrogen bonding. Solubility trends across all isotherms show two patterns: an initial rise with water content, followed by a decline after a solubility peak. This suggests an endothermic dissolution and a hydration effect at specific water levels. This work provides novel solubility data for theophylline in water-ethanol mixtures, absent in the literature, and generates 32 new interaction parameters for UNIFAC-Dortmund and ASOG models. The UNIFAC-Dortmund and ASOG activity coefficient models were fitted to the experimental data, generating new parameters. The UNIFAC-Dortmund parameters were used to predict theophylline solubility with the PSRK equation of state. Model performance was assessed with average relative deviation (ARD), root mean square deviation (RMSD), and Bayesian Information Criterion (BIC). The ASOG showed the best performance, followed by UNIFAC-Dortmund and PSRK.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"603 ","pages":"Article 114633"},"PeriodicalIF":2.7,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-19DOI: 10.1016/j.fluid.2025.114632
Cleiton S. Beraldo , Xiaodong Liang , Georgios M. Kontogeorgis , Luis A. Follegatti-Romero
We evaluate the performance of two electrolyte variants of the Statistical Associating Fluid Theory for Variable Range interactions (SAFT-VR) in the generic Mie form, the SAFT-VRE Mie and eSAFT-VR Mie equations of state, in predicting liquid-phase densities and the speed of sound for imidazolium-based ionic liquids (ILs) and their mixtures with water, methanol, and ethanol. A strictly predictive modeling strategy was employed: only pure-component IL densities were used to derive ion-specific molecular parameters (segment length, size, and energy) for imidazolium-based cations and anions, while solvent parameters were taken from the literature. Ion-solvent and ion-ion pair interactions were calculated via a simplified Hudson-McCoubrey combining rule, assuming equal ionization potentials and avoiding any binary parameter fitting. Six formulations of the relative static permittivity (constant, temperature‐dependent, linear in composition, and a volumetric‐composition model) were evaluated within both the SAFT-VRE Mie and eSAFT-VR Mie frameworks. We introduce a novel Born size interpretation that explicitly accounts for hydrogen‐bonding in IL ions, yielding improved agreement with experimental data. Furthermore, we identify quantitative correlations between these Born size and the underlying SAFT parameters, enabling predictive parametrization of related IL systems. The electrolyte models enhance performance over the SAFT-VR Mie, particularly in mixed‐solvent regions, though further refinement is needed near the pure‐IL limit. All calculations were conducted using the open‐source Clapeyron.jl toolkit, ensuring full reproducibility and extensibility.
{"title":"Modeling the thermodynamic properties of imidazolium ionic liquids in water, methanol, and ethanol using SAFT-VRE Mie and eSAFT-VR Mie equations of state","authors":"Cleiton S. Beraldo , Xiaodong Liang , Georgios M. Kontogeorgis , Luis A. Follegatti-Romero","doi":"10.1016/j.fluid.2025.114632","DOIUrl":"10.1016/j.fluid.2025.114632","url":null,"abstract":"<div><div>We evaluate the performance of two electrolyte variants of the Statistical Associating Fluid Theory for Variable Range interactions (SAFT-VR) in the generic Mie form, the SAFT-VRE Mie and eSAFT-VR Mie equations of state, in predicting liquid-phase densities and the speed of sound for imidazolium-based ionic liquids (ILs) and their mixtures with water, methanol, and ethanol. A strictly predictive modeling strategy was employed: only pure-component IL densities were used to derive ion-specific molecular parameters (segment length, size, and energy) for imidazolium-based cations and anions, while solvent parameters were taken from the literature. Ion-solvent and ion-ion pair interactions were calculated via a simplified Hudson-McCoubrey combining rule, assuming equal ionization potentials and avoiding any binary parameter fitting. Six formulations of the relative static permittivity (constant, temperature‐dependent, linear in composition, and a volumetric‐composition model) were evaluated within both the SAFT-VRE Mie and eSAFT-VR Mie frameworks. We introduce a novel Born size interpretation that explicitly accounts for hydrogen‐bonding in IL ions, yielding improved agreement with experimental data. Furthermore, we identify quantitative correlations between these Born size and the underlying SAFT parameters, enabling predictive parametrization of related IL systems. The electrolyte models enhance performance over the SAFT-VR Mie, particularly in mixed‐solvent regions, though further refinement is needed near the pure‐IL limit. All calculations were conducted using the open‐source <em>Clapeyron.jl</em> toolkit, ensuring full reproducibility and extensibility.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"603 ","pages":"Article 114632"},"PeriodicalIF":2.7,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-17DOI: 10.1016/j.fluid.2025.114630
M. G. De Angelis , E. Ricci , M. Minelli , E.A. Macedo
{"title":"Preface to the proceedings of the 33rd European symposium on applied thermodynamics (50th anniversary of ESAT) special issue","authors":"M. G. De Angelis , E. Ricci , M. Minelli , E.A. Macedo","doi":"10.1016/j.fluid.2025.114630","DOIUrl":"10.1016/j.fluid.2025.114630","url":null,"abstract":"","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"603 ","pages":"Article 114630"},"PeriodicalIF":2.7,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-13DOI: 10.1016/j.fluid.2025.114629
Mars Z. Faizullin, Eugene D. Nikitin
The two-phase (liquid + vapor) heat capacities of glymes CH3(OCH2CH2)nOCH3 with n from 1 to 4 (monoglyme, diglyme, triglyme and tetraglyme), as well as ethylene glycol, 2-propanol, n-octane, and benzoic acid have been measured by a differential scanning calorimeter DSC 204 F1 Phoenix (Netzsch, Germany) at atmospheric pressure in the temperature range from 298.2 K to approximately the normal boiling points of the compounds under study. The last four compounds have served as testing ones. The saturation heat capacity and isobaric heat capacity have been calculated. The experiments with testing compounds have shown that the uncertainty of the measurements is less than 0.03. The deviations of the literature data on the isobaric heat capacity of the glymes from the values measured in this work do not in general exceed the uncertainty of the experiments. The temperature dependences of the heat capacity of glymes have been approximated by third-order polynomials. The dependence of the molar heat capacity of glymes on the number of repeating units in a molecule n is linear.
用差示扫描量热计DSC 204 F1 Phoenix （Netzsch, Germany）测量了n为1 ~ 4（单lyme，二lyme，三lyme和四lyme）的glymes CH3(OCH2CH2)nOCH3以及乙二醇，2-丙醇，正辛烷和苯甲酸的两相（液+气）热容，温度范围从298.2 K到所研究化合物的正常沸点。后四种化合物被用作测试物。计算了饱和热容和等压热容。实验结果表明，测量结果的不确定度小于0.03。文献中关于糖份等压热容的数据与本工作测量值的偏差一般不超过实验的不确定度。glymes热容量的温度依赖性已用三阶多项式近似。分子的摩尔热容与分子中重复单位的数目呈线性关系。
{"title":"Heat capacity of glymes from monoglyme to tetraglyme","authors":"Mars Z. Faizullin, Eugene D. Nikitin","doi":"10.1016/j.fluid.2025.114629","DOIUrl":"10.1016/j.fluid.2025.114629","url":null,"abstract":"<div><div>The two-phase (liquid + vapor) heat capacities of glymes CH<sub>3</sub>(OCH<sub>2</sub>CH<sub>2</sub>)<sub>n</sub>OCH<sub>3</sub> with <em>n</em> from 1 to 4 (monoglyme, diglyme, triglyme and tetraglyme), as well as ethylene glycol, 2-propanol, n-octane, and benzoic acid have been measured by a differential scanning calorimeter DSC 204 F1 Phoenix (Netzsch, Germany) at atmospheric pressure in the temperature range from 298.2 K to approximately the normal boiling points of the compounds under study. The last four compounds have served as testing ones. The saturation heat capacity and isobaric heat capacity have been calculated. The experiments with testing compounds have shown that the uncertainty of the measurements is less than 0.03. The deviations of the literature data on the isobaric heat capacity of the glymes from the values measured in this work do not in general exceed the uncertainty of the experiments. The temperature dependences of the heat capacity of glymes have been approximated by third-order polynomials. The dependence of the molar heat capacity of glymes on the number of repeating units in a molecule <em>n</em> is linear.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"602 ","pages":"Article 114629"},"PeriodicalIF":2.7,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145569060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<div><div>The presence of impurities in CO<sub>2</sub> streams has implications in the design and operation of CCS systems. Due to the wide range of potential emitters and the chemical nature of the impurities, the phase behaviour of CO<sub>2</sub>-rich mixtures may be affected leading to integrity risks. Polar impurities, even at trace or low ppm-mol levels, can influence water solubility and induce a free aqueous phase at temperatures higher than the pure water dew point. This risk can manifest at conditions at which transport pipelines operate, highlighting the need for accurate determination of the dew point of the aqueous phase in the presence of polar molecules.</div><div>This paper evaluates the performance of various Equation of State (EoS) against experimental solubility data for polar components in CO<sub>2</sub>, aiming to highlight potential uncertainties inherent in standard industry tools used for Carbon Capture and Storage (CCS) pipeline transport systems. Specifically, the Cubic-Plus-Association (CPA) EoS, as implemented in the commercial property package <em>Multiflash</em>, was assessed for its ability to predict the solubility of polar impurities—such as methanol (MeOH), triethylene glycol (TEG), and ethylene glycol (MEG)—in binary CO<sub>2</sub>-rich systems. The results reveal the capabilities and limitations of the CPA EoS in accurately estimating polar component solubilities of polar component. Significant discrepancies were observed in the solubility predictions of MeOH, TEG, and MEG, with Average Absolute Deviations (AAD) of 34.4 %, 65.8 %, and 27.8 %, respectively. These deviations underscore the model’s limitations under varying conditions, primarily due to the complexity of intermolecular interactions and the inherent challenges in capturing them within a cubic EoS framework.</div><div>To enhance the prediction accuracy of the solubility of the polar component solubility in CO<sub>2</sub>, the CPA EoS was tuned using available literature experimental data. The EoS was optimized through a calibration process that involved fitting temperature-dependent binary interaction parameters (BIPs), and cross-association parameters. We focused on improving the accuracy of solubility predictions for MeOH, TEG, and MEG in CO<sub>2</sub>, as evidenced by a reduction in the Absolute Average Deviation (AAD) down to 21.6 %,19.3 %, and 13.4 %, respectively.</div><div>While the estimations of the CPA EoS are improved, there are still some limitations. Furthermore, experimental data deviations under similar pressure and temperature conditions, along with the limited availability of reliable measurements in CO<sub>2</sub> gas and supercritical conditions relevant to CCS pipeline operations, pose additional challenges for model validation and improving predictive capability across the wide range of conditions encountered in the CCS industry. To address these limitations, this study emphasizes the need for further experimental research to gen
{"title":"Solubility of TEG, MEG, and MeOH in CO2: Improving CPA EoS modelling for CCS transport applications","authors":"Dhanaraj Turunawarasu, Paula S.C. Farias, Ayuni Saidi, Arfa Amir, Eduardo Luna-Ortiz","doi":"10.1016/j.fluid.2025.114628","DOIUrl":"10.1016/j.fluid.2025.114628","url":null,"abstract":"<div><div>The presence of impurities in CO<sub>2</sub> streams has implications in the design and operation of CCS systems. Due to the wide range of potential emitters and the chemical nature of the impurities, the phase behaviour of CO<sub>2</sub>-rich mixtures may be affected leading to integrity risks. Polar impurities, even at trace or low ppm-mol levels, can influence water solubility and induce a free aqueous phase at temperatures higher than the pure water dew point. This risk can manifest at conditions at which transport pipelines operate, highlighting the need for accurate determination of the dew point of the aqueous phase in the presence of polar molecules.</div><div>This paper evaluates the performance of various Equation of State (EoS) against experimental solubility data for polar components in CO<sub>2</sub>, aiming to highlight potential uncertainties inherent in standard industry tools used for Carbon Capture and Storage (CCS) pipeline transport systems. Specifically, the Cubic-Plus-Association (CPA) EoS, as implemented in the commercial property package <em>Multiflash</em>, was assessed for its ability to predict the solubility of polar impurities—such as methanol (MeOH), triethylene glycol (TEG), and ethylene glycol (MEG)—in binary CO<sub>2</sub>-rich systems. The results reveal the capabilities and limitations of the CPA EoS in accurately estimating polar component solubilities of polar component. Significant discrepancies were observed in the solubility predictions of MeOH, TEG, and MEG, with Average Absolute Deviations (AAD) of 34.4 %, 65.8 %, and 27.8 %, respectively. These deviations underscore the model’s limitations under varying conditions, primarily due to the complexity of intermolecular interactions and the inherent challenges in capturing them within a cubic EoS framework.</div><div>To enhance the prediction accuracy of the solubility of the polar component solubility in CO<sub>2</sub>, the CPA EoS was tuned using available literature experimental data. The EoS was optimized through a calibration process that involved fitting temperature-dependent binary interaction parameters (BIPs), and cross-association parameters. We focused on improving the accuracy of solubility predictions for MeOH, TEG, and MEG in CO<sub>2</sub>, as evidenced by a reduction in the Absolute Average Deviation (AAD) down to 21.6 %,19.3 %, and 13.4 %, respectively.</div><div>While the estimations of the CPA EoS are improved, there are still some limitations. Furthermore, experimental data deviations under similar pressure and temperature conditions, along with the limited availability of reliable measurements in CO<sub>2</sub> gas and supercritical conditions relevant to CCS pipeline operations, pose additional challenges for model validation and improving predictive capability across the wide range of conditions encountered in the CCS industry. To address these limitations, this study emphasizes the need for further experimental research to gen","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"602 ","pages":"Article 114628"},"PeriodicalIF":2.7,"publicationDate":"2025-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-06DOI: 10.1016/j.fluid.2025.114618
Peiming Wang , Mohiedin Bagheri Hariri , Jerzy J. Kosinski , Basil Perdicakis , Andre Anderko
The dissolution behavior of iron oxides in high-temperature water containing various dissolved species is a critical factor for understanding and predicting the conditions that control flow-accelerated corrosion (FAC). Predicting the stability of passivating films under steam-generating conditions, which may give rise to FAC, requires an accurate thermodynamic model that is capable of predicting the solubility of film materials, particularly magnetite (Fe3O4), hematite (Fe2O3) and iron oxyhydroxides (FeOOH). This is essential for accurate corrosion prediction, particularly in applications such as steam generation for hydrocarbon recovery from oil sands, water/steam cycle boilers, power plants, boiler feedwater systems, etc. In this study, available experimental solubility data have been evaluated for iron oxides/hydroxides, and a comprehensive thermodynamic model has been developed using the Mixed Solvent Electrolyte (MSE) framework for temperatures up to 600 K and pressures exceeding 50 MPa. The MSE model reproduces solubility in the presence of various inorganic ions and additives used in all-volatile treatments (AVT) wherein volatile alkalizing agents are employed under either reducing conditions (i.e., AVT(R)) or oxidizing conditions (i.e., AVT(O)). The accuracy of model predictions is, in general, consistent with the inherent uncertainty of experimental solubility data while the distribution of errors is a function of pH and temperature, with elevated uncertainty observed for neutral and alkaline solutions. Further, the MSE model has been applied to predict magnetite stability across various AVT(R) scenarios with different dosages of alkaline and non-alkaline reducing agents (i.e., hydrazine, hydrogen) to provide a thermodynamic foundation for controlling environmental variables in mitigating AVT(R) flow-accelerated corrosion risks. This work is especially relevant to the Canadian oil sands industry, in particular to industrial steam generation applications such as oilfield once-through steam generation systems, where high temperatures and high pH conditions affect corrosion behavior.
{"title":"Modeling the solubility of iron oxides in wide temperature ranges: thermodynamic foundation for understanding flow-accelerated corrosion","authors":"Peiming Wang , Mohiedin Bagheri Hariri , Jerzy J. Kosinski , Basil Perdicakis , Andre Anderko","doi":"10.1016/j.fluid.2025.114618","DOIUrl":"10.1016/j.fluid.2025.114618","url":null,"abstract":"<div><div>The dissolution behavior of iron oxides in high-temperature water containing various dissolved species is a critical factor for understanding and predicting the conditions that control flow-accelerated corrosion (FAC). Predicting the stability of passivating films under steam-generating conditions, which may give rise to FAC, requires an accurate thermodynamic model that is capable of predicting the solubility of film materials, particularly magnetite (Fe<sub>3</sub>O<sub>4</sub>), hematite (Fe<sub>2</sub>O<sub>3</sub>) and iron oxyhydroxides (FeOOH). This is essential for accurate corrosion prediction, particularly in applications such as steam generation for hydrocarbon recovery from oil sands, water/steam cycle boilers, power plants, boiler feedwater systems, etc. In this study, available experimental solubility data have been evaluated for iron oxides/hydroxides, and a comprehensive thermodynamic model has been developed using the Mixed Solvent Electrolyte (MSE) framework for temperatures up to 600 K and pressures exceeding 50 MPa. The MSE model reproduces solubility in the presence of various inorganic ions and additives used in all-volatile treatments (AVT) wherein volatile alkalizing agents are employed under either reducing conditions (i.e., AVT(R)) or oxidizing conditions (i.e., AVT(O)). The accuracy of model predictions is, in general, consistent with the inherent uncertainty of experimental solubility data while the distribution of errors is a function of pH and temperature, with elevated uncertainty observed for neutral and alkaline solutions. Further, the MSE model has been applied to predict magnetite stability across various AVT(R) scenarios with different dosages of alkaline and non-alkaline reducing agents (i.e., hydrazine, hydrogen) to provide a thermodynamic foundation for controlling environmental variables in mitigating AVT(R) flow-accelerated corrosion risks. This work is especially relevant to the Canadian oil sands industry, in particular to industrial steam generation applications such as oilfield once-through steam generation systems, where high temperatures and high pH conditions affect corrosion behavior.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"602 ","pages":"Article 114618"},"PeriodicalIF":2.7,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-06DOI: 10.1016/j.fluid.2025.114615
Qing Yang, Shuai Peng, Yueting Zhu, Ke Chen, Jianfang Liu
The dissolution behavior of drugs is critical for understanding dissolution mechanisms and optimizing pharmaceutical formulations. This study investigated the solubility of the anti-rheumatic drug Iguratimod (IGU) in 12 organic solvents between 283.15 and 323.15 K at 101.3 kPa. Notably, solvent-induced polymorphic transformation yielded two distinct crystal forms: α and β. The Apelblat, λh, Yaws, NRTL, and Wilson models were employed to correlate the solubility data, with the Apelblat equation providing the most accurate prediction. Thermodynamic analysis shows that the dissolution of both polymorphs is endothermic and enthalpy-driven. Correlation analysis and Hirshfeld surface analysis indicate that the stability and solubility of crystal form α are mainly influenced by solvent polarity and hydrogen bond acidity. The crystal structure may be stabilized through an intrinsic hydrogen bonding network, and solubility is achieved in solvents that exhibit high polarity and low hydrogen bonding self-association tendency. The formation and solubility of crystal form β are determined by its unique crystal stacking mode, the formation of crystal structure is determined by the steric hindrance and weak hydrogen bonding donor ability of the solvent through dynamic pathway selection, and its solubility is mainly guided by the thermodynamic equilibrium between the lower lattice energy (HH and HO interactions) of the crystal itself and the high polarity solvation ability of the solvent. This work provides fundamental insights into solvent-induced polymorphic transformation, offering a theoretical basis for rational polymorph control and solvent selection in pharmaceutical processing.
{"title":"Solvent-driven polymorphic transformation and dissolution thermodynamics study of Iguratimod","authors":"Qing Yang, Shuai Peng, Yueting Zhu, Ke Chen, Jianfang Liu","doi":"10.1016/j.fluid.2025.114615","DOIUrl":"10.1016/j.fluid.2025.114615","url":null,"abstract":"<div><div>The dissolution behavior of drugs is critical for understanding dissolution mechanisms and optimizing pharmaceutical formulations. This study investigated the solubility of the anti-rheumatic drug Iguratimod (IGU) in 12 organic solvents between 283.15 and 323.15 K at 101.3 kPa. Notably, solvent-induced polymorphic transformation yielded two distinct crystal forms: α and β. The Apelblat, λh, Yaws, NRTL, and Wilson models were employed to correlate the solubility data, with the Apelblat equation providing the most accurate prediction. Thermodynamic analysis shows that the dissolution of both polymorphs is endothermic and enthalpy-driven. Correlation analysis and Hirshfeld surface analysis indicate that the stability and solubility of crystal form α are mainly influenced by solvent polarity and hydrogen bond acidity. The crystal structure may be stabilized through an intrinsic hydrogen bonding network, and solubility is achieved in solvents that exhibit high polarity and low hydrogen bonding self-association tendency. The formation and solubility of crystal form β are determined by its unique crystal stacking mode, the formation of crystal structure is determined by the steric hindrance and weak hydrogen bonding donor ability of the solvent through dynamic pathway selection, and its solubility is mainly guided by the thermodynamic equilibrium between the lower lattice energy (H<img>H and H<img>O interactions) of the crystal itself and the high polarity solvation ability of the solvent. This work provides fundamental insights into solvent-induced polymorphic transformation, offering a theoretical basis for rational polymorph control and solvent selection in pharmaceutical processing.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"602 ","pages":"Article 114615"},"PeriodicalIF":2.7,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145569059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-05DOI: 10.1016/j.fluid.2025.114617
Ibtissem Guennoun , Ilham Mokbel , Latifa Negadi , Jacques Jose , Joseph Saab
This study investigates the vapor pressures of the platform chemicals furfural and 5-methylfurfural, as well as their binary mixtures with bio-derived solvents γ-valerolactone and γ-butyrolactone, using a static isothermal apparatus. Measurements were conducted over a range of 5 Pa to 10 kPa and 273.15 K to 363.15 K. The experimental data for the pure compounds were compared with literature values, while no reference data were available for the binary systems. The results were subsequently correlated using the NRTL and UNIQUAC models.
{"title":"Experimental vapor-liquid equilibria of pure compounds and binary systems (furfural + γ-valerolactone or γ-butyrolactone) and (5-methylfurfural + γ-valerolactone or γ-butyrolactone) encountered in biorefineries","authors":"Ibtissem Guennoun , Ilham Mokbel , Latifa Negadi , Jacques Jose , Joseph Saab","doi":"10.1016/j.fluid.2025.114617","DOIUrl":"10.1016/j.fluid.2025.114617","url":null,"abstract":"<div><div>This study investigates the vapor pressures of the platform chemicals furfural and 5-methylfurfural, as well as their binary mixtures with bio-derived solvents γ-valerolactone and γ-butyrolactone, using a static isothermal apparatus. Measurements were conducted over a range of 5 Pa to 10 kPa and 273.15 K to 363.15 K. The experimental data for the pure compounds were compared with literature values, while no reference data were available for the binary systems. The results were subsequently correlated using the NRTL and UNIQUAC models.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"602 ","pages":"Article 114617"},"PeriodicalIF":2.7,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-05DOI: 10.1016/j.fluid.2025.114616
Ricardo Macías-Salinas , María Antonieta Zúñiga-Hinojosa , Obed Andrés Solis-González
The well-known Gradient Theory of Fluid Interfaces (GTFI) was coupled with a simple cubic equation of state (CEoS) to accurately calculate the surface tension of non-polar, polar, and associating fluids over a wide temperature range, from the triple point to the critical region. For most of the pure fluids studied, a remarkably accurate representation of reference surface tensions was obtained near their critical points, even though the homogeneous fluid portion of the GTFI was modeled using a simple CEoS, which typically fails to accurately describe fluid phase behavior near the critical point. To mitigate this limitation of the CEoS within the GTFI framework, a new scaling function for the influence parameter of the inhomogeneous fluid was introduced. The proposed expression for the influence parameter proved highly satisfactory, particularly near the critical point, when combined with the Soave-Redlich-Kwong (SRK) or Peng-Robinson (PR) CEoS in representing the reference surface tensions of various pure fluids, including normal paraffins, aromatics, CO2, SF6, alcohols, water, acetone, and others, thus yielding overall values of average absolute relative deviations of 1.67 % using the GTFI-SRK approach, and 1.78 % using the GTFI-PR approach.
{"title":"Surface-tension modeling of pure fluids using the gradient theory coupled with a cubic EoS","authors":"Ricardo Macías-Salinas , María Antonieta Zúñiga-Hinojosa , Obed Andrés Solis-González","doi":"10.1016/j.fluid.2025.114616","DOIUrl":"10.1016/j.fluid.2025.114616","url":null,"abstract":"<div><div>The well-known Gradient Theory of Fluid Interfaces (GTFI) was coupled with a simple cubic equation of state (CEoS) to accurately calculate the surface tension of non-polar, polar, and associating fluids over a wide temperature range, from the triple point to the critical region. For most of the pure fluids studied, a remarkably accurate representation of reference surface tensions was obtained near their critical points, even though the homogeneous fluid portion of the GTFI was modeled using a simple CEoS, which typically fails to accurately describe fluid phase behavior near the critical point. To mitigate this limitation of the CEoS within the GTFI framework, a new scaling function for the influence parameter of the inhomogeneous fluid was introduced. The proposed expression for the influence parameter proved highly satisfactory, particularly near the critical point, when combined with the Soave-Redlich-Kwong (SRK) or Peng-Robinson (PR) CEoS in representing the reference surface tensions of various pure fluids, including normal paraffins, aromatics, CO<sub>2</sub>, SF<sub>6</sub>, alcohols, water, acetone, and others, thus yielding overall values of average absolute relative deviations of 1.67 % using the GTFI-SRK approach, and 1.78 % using the GTFI-PR approach.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"602 ","pages":"Article 114616"},"PeriodicalIF":2.7,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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