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  • 更新日期:2020-01-14
  • Separation of thiophene from octane/hexadecane with ionic liquids in ternary liquid-liquid phase equilibrium
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-13
    Marcin Durski; Paramespri Naidoo; Deresh Ramjugernath; Urszula Domańska

    This work is a continuation of the investigations on desulfurization processes, by assessing the applicability of two ionic liquids (ILs), 1-butyl-1-methylpiperidynium dicyanamide, [BMPIP][DCA] and tri-iso-butylmethylphosphonium tosylate, [Pi4,i4,i4,1][TOS], for the separation of thiophene from octane, or hexadecane. The latter two components are used as model substances of the fuel stream. Experimental liquid-liquid phase equilibrium (LLE) data were obtained for four ternary systems {IL + thiophene + octane, or hexadecane} at temperature T = 308.15 K and pressure p = 101 kPa. The DCA-based IL showed better selectivity than the tosylate-based IL in the extraction of thiophene from both alkanes with much lower solute distribution ratio. The selectivity is acceptable in all systems in comparison with currently published data for different ILs. Chromatography analysis showed that the IL was not present in the octane, or hexadecane layer, which simplifies the process of separating the solvent from the hydrocarbon layer. The non-random two liquid (NRTL) model showed satisfactory correlation of the measured phase data.

    更新日期:2020-01-14
  • Predicting wax appearance temperature and precipitation profile of normal alkane systems: An explicit co-crystal model
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-11
    Meng Wang; Chau-Chyun Chen

    Wax precipitation is a major flow assurance issue for petroleum production, oil blending, downstream processing, and oil products usage. While numerous thermodynamic models have been proposed to calculate wax appearance temperature (WAT) and precipitation profile at temperatures below WAT, the existing models are correlative in nature and fail to comply with phase behavior experimentally observed for wax precipitation. This work presents a predictive thermodynamic model for wax precipitation based on an explicit co-crystal formation assumption for precipitated wax, a treatment consistent with experimental findings. With a simple Flory-Huggins expression accounting for the liquid phase nonideality and the treatment of lamella structure for wax precipitation below WAT, the model satisfactorily predicts WAT at low pressures for multicomponent paraffin mixtures and wax precipitation amounts and contents as the temperature drops below WAT.

    更新日期:2020-01-13
  • Competitive H2S–CO2 absorption in reactive aqueous methyldiethanolamine solution: Prediction with the ePC-SAFT equation of state
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-10
    Conor Cleeton; Odin Kvam; Riccardo Rea; Lev Sarkisov; Maria Grazia De Angelis
    更新日期:2020-01-11
  • Measurement and modelling of solid apparition temperature for the CO2 – H2S – CH4 ternary system
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-10
    Pascal Théveneau; Rémi Fauve; Christophe Coquelet; Pascal Mougin

    In order to develop a new process to eliminate acid gases from natural gas, it is important to consider phase equilibrium properties. New solid-liquid equilibrium data were determined concerning the ternary system CO2 + H2S + CH4. The experimental technique is based on visual synthetic method. The new experimental data were compared to predictions given by the Predictive Peng-Robinson equation of state (PPR78), PSRK UNIFAC, Peng-Robinson with Huron-Vidal mixing rules and GERG 2008 models coupling with classical approach or Jager and Span for solid phase. The results have shown that the model selected for the fluid phase has more impact that the model considered for the solid phase. New binary interaction parameters of Peng-Robinson equation of state were fitted only on our experimental data and it was found that the obtained values are very different from the value used for Vapor Liquid Equilibrium computation.

    更新日期:2020-01-11
  • A group contribution-based prediction method for the electrical conductivity of ionic liquids
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-09
    Yuqiu Chen; Yingjun Cai; Kaj Thomsen; Georgios M. Kontogeorgis; John M. Woodley

    A group contribution method is developed for estimating the electrical conductivity of ionic liquids (ILs). Based on 1578 collected experimental data covering 57 ILs in a wide range of temperature (248.05–468.15 K) and electrical conductivity (0.0017–9.1670 S m−1), the parameters of each group (cation, anion, substituent) in the method are optimized. A deterministic algorithm-based on multivariate linear regression is used with 1121 data points covering 57 ILs used as training set and the reaming 457 data points covering 20 ILs are used for validation. The prediction results (from test set) expressed as an average absolute relative deviation (AARD %) of 6.8% between the experimental and predicted electrical conductivities of ILs illustrate the good predictive capability of this group contribution method, with a maximum relative deviation (RD %) of 26.6%. This group contribution-based method can be easily extended to new IL groups that are not involved in this study once the experimental data of ILs involving these new groups become available.

    更新日期:2020-01-09
  • Corresponding state principle based correlation for the thermal conductivity of saturated refrigerants liquids from Ttr to 0.90Tc
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-08
    Shangguo Yang; Jianxiang Tian; Hua Jiang

    We here report that the corresponding state principle well stands for the temperature dependent thermal conductivity of the saturated refrigerants liquids by using the reduced quantities proposed here. A corresponding state principle based correlation is proposed and proven to be accurate in the temperature range from the triple point temperature to 0.90 times the critical temperature. Additionally, this correlation also stands for the saturated n-alkanes liquids. For the 23 refrigerants and 11 n-alkanes considered here, the proposed correlation can reproduce the REFPROP data with AAD<2% for 21 liquids, and AAD<5% for all the liquids considered.

    更新日期:2020-01-09
  • 更新日期:2020-01-08
  • 更新日期:2020-01-08
  • Thermodynamic study of ester diethyl tartrate and its binary systems with iso-alcohols
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-08
    Divna M. Majstorović; Ivona R. Radović; Mirjana Lj Kijevčanin; Emila M. Živković
    更新日期:2020-01-08
  • 更新日期:2020-01-07
  • 更新日期:2020-01-07
  • Measurement and correlation of the saturated vapor pressures of Ethenyltris(2,2,2-trifluoroethoxy)silane, Dimethoxymethyl(3,3,3-trifluoropropyl)silane and Trimethoxy(3,3,3-trifluoropropyl)silane
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-07
    Pan Jiang; Hong Dong; Wengeng Luan; Daowei Chen; Yunfeng Zheng; Liangbing Huang; Zhirong Qu; Chuan Wu

    The saturated temperature of ethenyltris(2,2,2-trifluoroethoxy)silane (trisF-ES), dimethoxymethyl(3,3,3-trifluoropropyl)silane (F-DiMOMS) and trimethoxy(3,3,3-trifluoropropyl)silane (F-TriMOS) were determined using an inclined ebulliometer from 3.00 to 100.00 kPa. The experimental data were fitted with the Antoine equation and the Clarke−Glew equation by a weighted least-squares regression method, and gave the Antoine parameters (A = 8.8461, B = 1207.11, C = −114.06 K, A = 8.8040, B = 1166.06, C = −97.69 K and A = 8.9712, B = 1279.86, C = −92.77 K) and standard vaporization enthalpy ΔlgHm0(298.15 K) = 55.84 kJ mol−1, ΔlgHm0(298.15 K) = 47.54 kJ mol−1 and ΔlgHm0(298.15 K) = 49.48 kJ mol−1 for trisF-ES, F-DiMOMS and F-TriMOS, respectively. The critical properties of trisF-ES, F-DiMOMS and F-TriMOS, including critical temperature, pressure, and volume, were estimated by the group contribution method introduced by Nannoolal et al. The acentric factors (ω) of trisF-ES, F-DiMOMS and F-TriMOS were estimated from these critical parameters and the reduced saturated vapor pressures calculated using both the Antoine equation and the Clarke−Glew equation.

    更新日期:2020-01-07
  • Solvation structure and molecular interactions of ibuprofen with ethanol and water: A theoretical study
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-03
    Mao Zhang; Yiping Huang; Dule Hao; Yuanhui Ji; Defang Ouyang
    更新日期:2020-01-04
  • Measurements and calculations of solid-liquid equilibria in two quaternary systems: LiCl–NaCl–SrCl2–H2O and LiCl–KCl–SrCl2–H2O at 298 K
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-03
    Guo-Liang Nie; Shi-Hua Sang; Rui-Zhi Cui; Zhong-Zhong Wu; Chao Ye; Yun-Yun Gao

    Using the method of isothermal dissolution equilibrium, stable phase equilibria of unreported strontium-containing systems LiCl–NaCl–SrCl2–H2O and LiCl–KCl–SrCl2–H2O at 298 K have been studied in accordance with the compositions of the underground brine in western Sichuan Basin. The experimental results show that there are no solid solution and complex salt in two quaternary systems. The phase diagram of quaternary system LiCl–NaCl–SrCl2–H2O consists of two invariant points, five isothermal dissolution curves and four crystallization regions. The quaternary system LiCl–KCl–SrCl2–H2O belongs to a simple type and the phase diagram consists of two invariant points, five isothermal dissolution curves and four crystallization regions. The solubilities of salts in the above systems were accurately calculated with Pitzer electrolyte solution theory. It was found that the calculated phase diagrams coincided basically with the experimental phase diagrams by evaluated the accuracy through the experimental results. Meanwhile, the applicability of Pitzer parameters selected in this paper was validated.

    更新日期:2020-01-04
  • Measurement and correlation of liquid–liquid equilibrium data for the ternary systems tetrabutylammonium dicyanamide + 1-propanol/2-propanol + water at different temperatures
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-02
    Shuai Xu; Zhengrong Xu; Qi Zhu; Chong He; Yanlin Qin; Yuliang Li

    In this work the ionic liquid tetrabutylammonium dicyanamide ([N4,4,4,4][dca]) was selected as extraction solvent to separate 1-propanol (NPA) and 2-propanol (IPA) from their aqueous solutions. The experimental liquid-liquid equilibrium data for the ternary systems ([N4,4,4,4][dca] + NPA/IPA + H2O) were measured at 303.15, 308.15, 313.15 and 323.15 K and atmospheric pressure. The equilibrium data were correlated by the NRTL model, and the consistency of correlation parameters was checked. Furthermore, the extraction capability of [N4,4,4,4][dca] was evaluated using distribution coefficients and selectivities. These parameters, for the ternary systems studied, increase with decreasing temperature. This study shows that [N4,4,4,4][dca] is a promising solvent for the extraction of NPA and IPA from water.

    更新日期:2020-01-02
  • Viscosity and self-diffusion coefficient of dipolar liquids
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-01
    S. Nagy; D. Balogh; I. Szalai

    Equilibrium molecular dynamics simulations were used to calculate the viscosity and self-diffusion coefficient of Stockmayer fluids at different dipole moments from the saturated liquid state to the supercritical fluid state. On the basis of the theory of Longuet-Higgins and Pople (J. Chem. Phys. 25 (1956) 884) a physically based correlation equations was proposed for the correlation of density, temperature and dipole moment dependence of viscosity and self-diffusion coefficient simulation data. As an application, with appropriate Stockmayer parameter sets the viscosity of fluoroalkanes were calculated along the saturated liquid curves, and good agreement has been obtained between the experimental and correlation equation data.

    更新日期:2020-01-01
  • Contribution of different chemical groups to the driving forces for the partition of phenylmethane dyes in the PEO1500 + MgSO4 + H2O aqueous two-phase system
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2020-01-01
    Elkin Dario C. Castrillon; Yara L. Coelho; Álvaro Javier P. Agudelo; Isabela A. Marques; Eliara A. Hudson; Ana Clarissa S. Pires; Luis Henrique M. da Silva
    更新日期:2020-01-01
  • Molecular insights into the microstructure of ethanol/water binary mixtures confined within typical 2D nanoslits: The role of the adsorbed layers induced by different solid surfaces
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-31
    Yao Qin; Nana Zhao; Yudan Zhu; Yumeng Zhang; Qingwei Gao; Zhongyang Dai; Yajing You; Xiaohua Lu

    With the emergence of membrane separation and heterogeneous catalysis applications that are associated with confined ethanol/water binary mixture in the pores of two-dimensional (2D) nanomaterials, understanding their confined microstructures is the first step for further relevant applications. In this work, molecular dynamics was performed to investigate the microstructure of ethanol/water binary mixture of 5% mole fraction confined within the four typical 2-nm width 2D-nanoslits (i.e. hBN, GO-0.2, GO-0.4 and Ti3C2(OH)2). Results demonstrated that different chemical properties of solid surfaces can induce distinctive microstructures of mixed fluid within the interfacial contact (adsorbed) layer and thus can result in different mobility of water molecules within the subcontact layer. The residence times of water molecules in the subcontact layer were found in the sequence of Ti3C2(OH)2 > hBN > GO-0.4 > GO-0.2, whereas their sequence of diffusion coefficient within the x-z plane was Ti3C2(OH)2 > hBN > GO-0.2 > GO-0.4. Detailed hydrogen bond (HB) microstructure analysis showed that a high average number of HBs (between fluid molecules of the interfacial contact layer and water molecules of the subcontact layer) induced by solid surfaces could facilitate water molecules to reside in the subcontact layer. Moreover, the small average number of HBs between the water molecules themselves in the subcontact layer could lead to high in-plane diffusion coefficients.

    更新日期:2019-12-31
  • 更新日期:2019-12-31
  • Lattice Boltzmann simulation of swelling behavior of cylindrical IPN hydrogel tablets
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-30
    Pedro J. Boschetti; Orlando Pelliccioni; Marcos A. Sabino; Natalia Vera; María F. Pappaterra

    This manuscript presents a computational method based on a multiple-relaxation-time lattice Boltzmann method to simulate the swelling behavior of cylindrical IPN hydrogel tablets in contact with buffer solutions at different pH and temperature conditions. The simulations were performed by a lattice Bolztmann model for axisymmetric mass diffusion equation using dimensionless measurements of length and mass; therefore, the mass sample estimation at each time step was not linked to the volume of the tablet. Adsorption isotherm tests were carried out using two IPN hydrogel formulations and copolymeric hydrogel formulation at temperatures equal to 298.15 K (25 °C) and 310.15 K (37 °C) and pH equal to 7.49, 4.72 and 8.22. The results show the reliability of the computational model by reproducing with high accuracy the experimental behavior of the hydrogel swelling process. The temperature and pH effect on equilibrium diffusion coefficient was also investigated by the variations on equilibrium diffusion coefficient. According with the state-of-the-art presented in this paper, the literature does not report the use of LBM to simulate this phenomenon in three-dimensional hydrogels; and neither reports were found related IPN hydrogels, nor varying the pH and temperature conditions which modify the diffusion processes.

    更新日期:2019-12-30
  • Experimental thermophysical properties and DFT calculations of imidazolium ionic liquids and 2-butanol mixtures
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-30
    Urooj Fatima; Riyazuddeen; Mohammad Jane Alam; Shabbir Ahmad

    Thermophysical properties, densities (ρ), speeds of sound (u) and dynamic viscosities (η) of binary mixtures constituting 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][CF3SO3])/1-ethyl-3-methylimidazolium ethyl sulfate ([EMIM][EtSO4]) (ILs) and 2-butanol have been measured experimentally. The obtained experimental data are further utilized to determine the excess molar volumes (VE), excess molar isentropic compressibilities (ΚsmE) and viscosity deviations (Δη) to gain insight into the molecular interactions of IL-2-butanol mixtures. In order to understanding the model fitting, the derived/excess properties are fitted to the Redlich-Kister polynomial equation. To unravel the effect of anions [CF3SO3]- and [EtSO4]- on molecular interactions, the Density Functional Theory (DFT) has been performed which provides the in-depth information about interactions in isolated ILs and their mixtures using DFT/D3-B3LYP method. Furthermore, the natural bond orbital (NBO) analysis has been performed to probe all possible interactions between donor-acceptor NBOs. This project aims to provide the experimental data of studied thermophysical properties properties and to obtain the interactional information at the molecular level between ILs having common cation and different anions and the solvent molecules in binary mixtures, which are interpreted in terms of ion-ion, ion-dipole and dipole-dipole interactions.

    更新日期:2019-12-30
  • Liquid surface tension, kinematic viscosity, density and refractive index of the binary mixtures of n-hexadecane with methyl butyrate and methyl decanoate close to saturation conditions
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-29
    Guanjia Zhao; Zemin Yuan; Jianguo Yin; Suxia Ma

    To facilitate the application of clean alternative fuels or fuel additives in compression ignition engines and a better understanding of the characteristics of their combustion and emission, physical biofuel surrogates are necessary to be proposed in computation and the knowledge of their thermophysical properties, such as liquid density, surface tension and viscosity, are also crucial for the design and optimization of the fuel injection system. Therefore, the surface light scattering (SLS) method was adopted for the simultaneous determination of the liquid surface tension and kinematic viscosity of the binary mixtures containing n-hexadecane, methyl butyrate and methyl decanoate in the temperature range between (353.15 and 423.15) K in the present work. Additionally, a U-tube densimeter and refractometer were used to obtain the liquid density and refractive index of the binary mixtures in the temperature range from (293.15–423.15) K and (293.15–358.15) K, respectively. Correlations for all thermophysical properties against temperature and mole fraction were also proposed. The relative deviations of liquid density, refractive index, kinematic viscosity as well as surface tension data from those calculated by the proposed equations were within ±0.3%, ±0.20%, ±2% and ±1%, respectively for the binary systems.

    更新日期:2019-12-29
  • Experimental determination of the dew point pressure for bulk and confined gas mixtures using an isochoric apparatus
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-27
    Shadi Salahshoor; Mashhad Fahes

    A robust high precision experimental approach to determine the Dew Point Pressure (DPP) of the gas condensates in a nano-porous medium is presented in this study. Gas condensate reservoirs have been the center of attention for numerous numerical and experimental studies for decades. Therefore, accurate measurement of DPP is crucial in developing long-term production plans for these reservoirs. This paper presents for the first time a proof of concept for a procedure to study the effect of the pore size distribution on the degree and direction of the shift in the saturation pressure of hydrocarbon gas mixtures under confinement over a relevant range of pressures and temperatures. Isochoric method, an indirect high-precision way of phase transition point determination, is commonly used in other disciplines where a clear non-visual determination of phase transition of a fixed volume of fluid is needed. This study provides an insight into using this approach for determining DPP of gas mixtures inside and outside of the porous media. A semi-automated apparatus for measuring and monitoring equilibrium conditions along with fluid properties is designed based on the isochoric method. The apparatus provides constant volume, variable pressure (0–104 bar), and variable temperature (290–410 K) experimental conditions. Pressure and temperature measurements provide a way to detect the phase transition point along the constant-mole-constant-volume line based on the change in the slope of this line at the phase transition point. A packed bed of BaTiO3 nanoparticles, providing a homogenous porous medium with pores of 1–70 nm is used as a representative nano-scale porous medium. The synthesized porous medium is very helpful in uncoupling the effect of pore size from the effect of mineralogy on the observed deviations in behavior, providing a volume more than 1000 times larger than the typical nano channels. The result is a set of isochoric lines for bulk and confined sample, plotted on the mixture's corresponding phase envelope to demonstrate the change in the saturation pressure. Phase envelopes (P-T diagrams) of the same mixture using different equations of state are created and the accuracy of each of these equations of state in providing an estimate of the experimentally detected DPP is discussed. Many attempts in explaining the shift in saturation pressures of the reservoir fluid confined in the narrow pores of unconventional reservoirs compared to those of the bulk can be found in the literature. However, there are some contradictions between the predicted behavior using different mathematical approaches. Experimental data could be substantially helpful in both validating the models and improving the understanding of the fluid behavior in these formations. Contrary to what many published models proposed, our results show that confinement effect shifts the DPP towards higher values compared to the bulk for a fixed temperature in the retrograde region. Capillary condensation is identified as the main source of the deviations observed in the behavior of fluids inside the nanopores. We evaluated some published models, including those based on EoS modifications, by comparing those to the experimental results which provides a quantification of their accuracy in estimating saturation pressure values for the confined mixtures.

    更新日期:2019-12-27
  • Thermodynamics of the carbon dioxide plus nitrogen plus methane (Co2 + N2 + Ch4) system: Measurements of vapor-liquid equilibrium data at temperatures from 223 to 298 K and verification of Eos-Cg-2019 equation of state
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-27
    Sindre Ottøy; Tobias Neumann; Hans Georg Jacob Stang; Jana Poplsteinova Jakobsen; Anders Austegard; Sigurd Weidemann Løvseth
    更新日期:2019-12-27
  • Predictive models for physical properties of fats, oils, and biodiesel fuels
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-24
    Ericsem Pereira; Antonio J.A. Meirelles; Guilherme J. Maximo

    Physicochemical properties determine in large extent the application of fats and oils, considering products’ formulation, and the design of equipment and processes in the food industry. These lipids have also been highly significant in the development of the bioenergy industry due to the increasing demand for biodiesel worldwide, whose physical properties should attend strict standards specifications. Fats, oils, and biodiesel are multicomponent systems which present complex phase equilibrium profile. Thus, the phase equilibrium behavior of these lipids plays a crucial role in their physicochemical properties. In this context, several thermodynamic modeling approaches have been used to predict the behavior of lipids and design products with desired properties. In this paper, we critically review and summarize the current state of knowledge of predictive modeling approaches used for the calculation of physicochemical properties of fats, oils, and biodiesel with a special focus on properties related to product design, such as melting/crystallization behavior and viscosity. The most remarkable publications dealing with predictive modeling are analyzed, and the underlying thermodynamic concepts used in those approaches, as well as their limitations, are assessed. Finally, we discuss future perspectives and indicate challenges to improve the research area.

    更新日期:2019-12-25
  • Semi-clathrate hydrate phase equilibria of carbon dioxide in presence of tetra-n-butyl-ammonium chloride (TBAC): Experimental measurements and thermodynamic modeling
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-23
    Kamalodin Momeni; Abolfazl Jomekian; Bahamin Bazooyar

    The promotion effect of TBAC on the dissociation condition of the studied system is determined under the present experimental data. A combination of the van der Waals–Platteeuw solid solution theory, binding mean spherical approximation electrolyte model and modified Peng–Robinson equation of state is used for calculation of the hydrate, aqueous solution and gaseous phases properties, respectively. The results are also compared with the experimental data for other salts such as tetra-n-butyl-ammonium bromide (TBAB) and tetra-hydro furan (THF). A good agreement between the model predictions and experimental data is found with an absolute average relative deviation of 13.1%.

    更新日期:2019-12-23
  • Selective extraction of female hormones using aqueous two-phase system composed of double protic ionic liquid + acetonitrile
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-23
    Filipe S. Buarque; Victor S. Barreto; Cleide M.F. Soares; Ranyere L. Souza; Matheus M. Pereira; Álvaro S. Lima

    Estrogens are currently considered the most prescribed drugs in the world. These contaminants are not entirely metabolized by humans and therefore, they have been detected in different effluents. Several studies already demonstrated that the hormones are classified as the major responsible for causing endocrine changes in living organisms. In this context, this work aims the selective extraction of hormones based on aqueous two-phase systems (ATPS) composed of acetonitrile (ACN) + double protic ionic liquids (PILs) + water. The respective ATPS pseudo-ternary phase diagrams, were determined at 298.15 ± 1.00 K and 0.10 ± 0.01 MPa. Thereby, their performance as extraction strategies was evaluated using four hormones (Progesterone, 17β-estradiol, estriol and 17α-ethinylestradiol). The binodal curve follows the order of PILs hydrophobicity, exhibiting intermediate biphasic region size between systems using the single PILs. The systems were able to extract selectively two hormones for each phase. Progesterone (PROG) and 17β-estradiol (E2) preferentially migrated to the ACN-rich phase (K > 1), while estriol (E3) 17α-ethinylestradiol (EE2) has higher affinity for the PIL-rich phase (K < 1). Maximum extraction was reached using ATPS formed by 50% of each PIL in a single-step: PROG (99.93%), E2 (99.92%), E3 (99.90%) and EE2 (99.92%). The results obtained show that ATPS based on ACN + double PIL allow the selective extraction of hormones.

    更新日期:2019-12-23
  • Liquid-liquid equilibria of aqueous two-phase systems made of polyethylene glycol and gelatin systems and their application in emulsion formation
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-20
    Jia Min Lee; Eng-Seng Chan; Ramakrishnan Nagasundara Ramanan; Chien Wei Ooi

    Water-in-water (W/W) emulsion is an interesting template for microentrapment of hydrophilic compounds due to biocompatible nature of its aqueous media. W/W emulsification can be established from a destabilised aqueous two-phase system (ATPS). In this study, binodal data of ATPSs comprising polyethylene glycol (PEG) and gelatin were generated. Binodal curves of PEG + gelatin + water systems were successfully correlated using non-linear empirical Merchuk equation, and the tie lines were constructed using lever-arm rule. Effects of temperature, type of gelatin, and molecular weight of PEG on the binodal curves were evaluated. Notably, a higher molecular weight of PEG decreased the concentration of gelatin required for two-phase formation. ATPSs made of gelatin bovine has a larger biphasic region than that of gelatin porcine. Gelatin microgel was successfully synthesized from the PEG/Gelatin emulsion system via rapid cooling of dispersed phase of gelatin. Size of gelatin microgel was reduced by a higher stirring speed, while a temperature as high as 333.15 K increased the size distribution of gelatin microgel. Lastly, the microentrapment of model protein, green fluorescent protein, was demonstrated. PEG/Gelatin system holds good potential for food engineering and delivery system.

    更新日期:2019-12-21
  • Phase equilibria of systems containing oxygenated compounds: Polar or “pseudo-association” approach?
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-18
    NguyenHuynh Dong; Siem T.K. Tran; Chau T.Q. Mai
    更新日期:2019-12-19
  • A norm indexes-based QSPR model for predicting the standard vaporization enthalpy and formation enthalpy of organic compounds
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-17
    Xue Yan; Tian Lan; Qingzhu Jia; Fangyou Yan; Qiang Wang

    As important thermodynamic properties, vaporization enthalpy and formation enthalpy were extensively utilized in the chemical industry process and chemical engineering design, environment and agriculture. Based on the concept of norm index proposed by our group previously, a unified QSPR model was built for predicting four properties endpoints for 14 families of organic compounds. Four thermodynamic properties endpoints, including standard vaporization enthalpy (ΔHv0), standard formation enthalpy in gas state (ΔHf0(g)), standard formation enthalpy in solid state (ΔHf0(s)) and standard formation enthalpy in liquid state (ΔHf0(l)), were involved in the same modelling work. This model has satisfactory fitting effect for four properties endpoints with R2 of 0.967 for ΔHv0, R2 of 0.990 for ΔHf0(g), R2 of 0.989 for ΔHf0(s) and R2 of 0.987 for ΔHf0(l), respectively. Moreover, the results of internal validation, external validation and applicability domain analysis indicated the good stability and robustness of this model. This work not only calculated vaporization enthalpy and formation enthalpy with the same formula, but also covered gas, solid and liquid phases for formation enthalpy. Satisfying results obtained in the present work suggest that this model and norm indexes have good reliability and generalization.

    更新日期:2019-12-18
  • Experimental and modeling investigation of adsorption equilibrium of CH4, CO2, and N2 on activated carbon and prediction of multi-component adsorption equilibrium
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-17
    Vahab Ghalandari; Hassan Hashemipour; Hamidreza Bagheri

    In this study, the equilibrium adsorption isotherms of N2, CH4 and CO2 on two types of activated carbon adsorbents were measured. The experimental data of the equilibrium adsorption were fitted to the Sips isotherm model at different temperatures. It was found that the Sips model is appropriate to predict the behavior of gas adsorption. Moreover, a method based on the Gibbs energy of desorption of the solid adsorbent was used to estimate the amount of separation factor of binary mixtures at different temperatures. Also, the amount of gas adsorption on activated carbon was predicted by using the artificial neural network-genetic algorithm (ANN-GA) model. The results of the ANN-GA model indicated that the performance of the model for predicting the behavior of gas adsorption is acceptable. Finally, the extended Sips model was used to simulate the multi-component adsorption of three binary mixtures CO2/N2, CH4/N2 and CO2/CH4, and the results of this model were validated by experimental data.

    更新日期:2019-12-18
  • Continuous aqueous two-phase extraction: From microfluidics to integrated biomanufacturing
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-17
    Diogo Ferreira-Faria; M. Raquel Aires-Barros; Ana M. Azevedo

    Aqueous two-phase extraction (ATPE) has been used since the 1960s, but even having advantages as high recovery yields and selectivity and relatively low cost, it has not been extensively adopted by the biotechnological industry. Recently, the production of bioproducts is entering a new era, where the continuous mode processes are spreading, and the high degree of integration of the ATPE makes them suitable for this kind of processes, however, few studies were done. The following review presents the brief history and the key challenges of continuous ATPE until nowadays and the main devices used, discussing the importance of the microfluidics in the study and development of continuous ATPE, and it analyses the future challenges. In the end, it can be concluded that continuous ATPE has not overcome some major challenges, but it will be an important tool in the downstream processing of biomolecules.

    更新日期:2019-12-18
  • Densities, speed of sound, and derived thermodynamic properties of toluene, tetradecane, and 1-chlorohexane in the compressed liquid region
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-12
    Alexander P. Shchamialiou; Vladimir S. Samuilov; Fares M. Mosbakh; Nadejda V. Holubeva; Aleh G. Paddubski; Dana Drăgoescu; Florinela Sîrbu

    The densities have been measured at temperatures from (273.65–473.15) K and pressures up to 140.1 MPa for toluene, at temperatures from (298.15–433.15) K and pressures up to 100.1 MPa for tetradecane, and 1-chlorohexane. The speeds of sound in liquid toluene and 1-chlorohexane have been measured over the temperature range from (298.15–433.15) K under pressures up to 100.1 MPa. The relative combined expanded uncertainty in the measurement of the density is 0.0003, and of the speed of sound is 0.001, both for 0.99 level of confidence. The values of the heat capacity at constant pressure and at constant volume, isobaric thermal expansivities, isothermal and isentropic compressibilities have been calculated at temperatures between 273.15 K and 473.15 K at pressures up to 140 MPa for toluene, at temperatures between 293.15 K and 433.15 K at pressures up to 100 MPa, for tetradecane, and at temperatures between 298.15 K and 433.15 K at pressures up to 100 MPa for 1-chlorohexane.

    更新日期:2019-12-13
  • Computational comparison of the application of doping, functionalization and ion exchanged of adsorbent structures on the pressure swing adsorption
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-10
    Ehsan Ekramian, Seyedfoad Aghamiri, Mohammad Reza Talaie, Hassan Sabzyan

    In this work, a grand canonical Monte Carlo (GCMC) simulation was performed to evaluate the performance of three types of modifications on the adsorption isotherms of pristine and modified crystal structures of two metal organic frameworks (MOFs) of Zn-MOF-74 and Zn-IRMOF-13. These modifications were: (i) doping by nickel and magnesium ions, (ii) functionalization with OH, CH3, and NH2 groups, and (iii) ion exchange with magnesium and copper ions. The CO2 working capacity, CO2/N2 selectivity, and selection parameters of each pristine and modified structures was calculated. The results showed that among all of modified structures, the copper ion exchange modification of Zn-MOF-74 has the largest selection parameter of 2858 and 250, and this modification can increase the selection parameters by 590 and 455% than the pristine structure, in the pressure ranges of 10–100 kPa, and 100–1000 kPa, respectively. Therefore, among all of structure modifications studied in this work, the adsorbent structure modification with copper ion exchange and the application of Cu-MOF-74 is the most appropriate for both vacuum and pressure swing adsorption processes.

    更新日期:2019-12-11
  • Measurement of the speed of sound in supercritical n-pentane at temperatures from (422.69–653.53) K and pressures from (3.5–10.0) MPa
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-07
    Ying Zhang, Qi Zhou, Taotao Zhan, Junshuai Chen, Maogang He

    n-Pentane is one of the main components in many industrial fluids, and is widely used as the fuel. The speed of sound can be used for developing the Helmholtz energy formulation and calculating other thermodynamic properties, which has not been reported yet for supercritical n-pentane. In this paper, the speed of sound in supercritical n-pentane was measured by the Brillouin light scattering (BLS) technique within the temperature limits of (422.69–653.53) K along four isobars at p = (3.5, 6.0, 8.0, and 10.0) MPa. The relative uncertainty of our BLS experimental system is estimated to be less than 0.6% and the relative uncertainty of the reported speed of sound values is estimated to be 0.85% considering the influence of impurities in the sample. The dependences of the speed of sound on temperature and pressure were also analyzed. At the end, we compared the experimental data with the calculated values from the multiparameter EOS proposed by Span and Wagner and the Modified BWR EOS proposed by J. Ratanapisit and J.F. Ely. The AARD is 1.3% for the multiparameter EOS and 1.5% for the Modified BWR EOS, respectively.

    更新日期:2019-12-07
  • Predicting the surface tension of mixtures of fatty acid ethyl esters and biodiesel fuels using UNIFAC activity coefficients
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-02
    Nayereh Sadat Mousavi, Ascención Romero-Martínez, Luis Felipe Ramírez-Verduzco

    This work presents the use of a formal thermodynamic model together with UNIFAC activity coefficients model, without any further adjustable parameter, to predict the surface tension of biodiesel fuels based on the equality of chemical potentials between the vapor-liquid interface and liquid bulk. The biodiesel samples included in this work were reported previously in the open literature. They were produced from vegetable oils such as: canola, coconut, corn, cottonseed, hazelnut, lard, palm, peanut, rapeseed, safflower, soybean, sunflower, and Walnut. Surface tension values for 18 samples of binary, ternary and quaternary mixtures of fatty acid ethyl esters (FAEEs) at T = 298.15 were predicted with an average absolute relative deviation (AARD) = 1.39%. Surface tension values for 31 biodiesel samples composed by fatty acid methyl esters (FAMEs) were also predicted at temperatures from 303.15 K to 353.15 K. The AARD value obtained for the 78 experimental points of biodiesel samples was 1.86% which shows a very good agreement with experimental measurements. In the UNIFAC method, predictions of surface tension values for the mixtures are based on the knowledge of the values of the surface tension for the pure components; these values were obtained from different sources. Also, two simple mixing rules on mass and mole fraction basis were used to predict the surface tension of biodiesel fuels. The AARD value obtained from the comparison between experimental and calculated values were: 2.77% and 2.91% for mixing rules on mass and mole fractions, respectively.

    更新日期:2019-12-02
  • Liquid-liquid equilibrium data and thermodynamic modeling of systems involved in the biodiesel production in terms of acylglycerols, free fatty acids, ethyl esters, and ethanol at 303.2 and 318.2 K and local pressure
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-02
    Simone Shiozawa, Daniel Gonçalves, Marcela C. Ferreira, Antonio J.A. Meirelles, Eduardo A.C. Batista

    Researches on renewable fuels as biodiesel are being done due to the global concern about the shortage of non-renewable natural energy resources. For the biodiesel production, vegetable oils are transesterified with short-chain alcohols, generating intermediate compounds as monoacylglycerols (MAG) and diacylglycerols (DAG). In order to understand the first stage of the transesterification reaction during the biodiesel production, this study reported experimental liquid-liquid equilibrium (LLE) data and the thermodynamic modeling of systems composed of refined oil (soybean, cottonseed, and rice bran) + commercial mixture of partial acylglycerols (MAG and DAG) + free fatty acids (FFA) + fatty acid ethyl esters (FAEE) + ethanol at T = (303.2 and 318.2) K. The LLE experimental data were thus used to adjust the NRTL model parameters and to evaluate three parameters sets of the UNIFAC model. Calculated Results by the NRTL model were well correlated to the experimental ones, with mass deviations up to 0.32%, whereas the deviations calculated for the UNIFAC model ranged from 1.04 to 9.46%. FFA and MAG exhibited preference to the solvent-rich phase, whereas FAEE and DAG preferred the oil-rich phase. New and more complex LLE data considering partial acylglycerols, FFA, besides the FAEE, as here reported, can assist to describe the real behavior of the transesterification step involved in the biodiesel production process and, consequently, its optimization.

    更新日期:2019-12-02
  • Separation of azeotropic mixture isopropyl alcohol + ethyl acetate by extractive distillation: Vapor-liquid equilibrium measurements and interaction exploration
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-12-01
    Yi Zhang, Xin Xu, Hui Yang, Jun Gao, Dongmei Xu, Lianzheng Zhang, Yinglong Wang

    Isopropyl alcohol and ethyl acetate can be used to produce degradable and renewable fuel. Since isopropyl alcohol + ethyl acetate can form an azeotropic mixture, it is a tough task to separate the binary mixture by general distillation. In this work, extractive distillation process with N, N-dimethylformamide and dimethyl sulfoxide as entrainers was adopted to separate this azeotrope. The binary and ternary vapor-liquid equilibrium data for (isopropyl alcohol + N, N-dimethylformamide), (ethyl acetate + dimethyl sulfoxide), (isopropyl alcohol + ethyl acetate + N, N-dimethylformamide) and (isopropyl alcohol + ethyl acetate + dimethyl sulfoxide) were determined under 101.3 kPa. Meanwhile, the interaction energies between the molecules were calculated to provide the theoretical insight into the separation of the azeotrope of (EA + IPA) by the entrainers. In addition, the NRTL, UNIQUAC and Wilson models were used to fit the determined binary VLE data. The ternary VLE data for (isopropyl alcohol + ethyl acetate + N, N-dimethylformamide) and (isopropyl alcohol + ethyl acetate + dimethyl sulfoxide) were predicted using the NRTL, UNIQUAC and Wilson models with the parameters regressed from the experimental data.

    更新日期:2019-12-02
  • Solid-liquid phase equilibrium determination and correlation of ternary systems NH4Cl+AlCl3+H2O, MgCl2+AlCl3+H2O and SrCl2+AlCl3+H2O at 298 K
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-30
    Xudong Yu, Qiufeng Zheng, Lin Wang, Min Liu, Xinglong Cheng, Ying Zeng

    The equilibrium data (solubility, density and refractive index) of three aqueous ternary systems NH4Cl + AlCl3+H2O, MgCl2+AlCl3+H2O, and SrCl2+AlCl3+H2O at 298 K were measured by isothermal dissolution method, and the corresponding diagrams were plotted. The phase diagram shows that these three systems are simple eutectic type, and neither double salt nor solid solution formed. Three ternary systems all have one ternary invariant point, two isothermal dissolution curves and two crystallization fields. The equilibrium thermodynamics data of three aqueous ternary systems at 298 K were correlated by using the Pitzer thermodynamic model. Result shows that the calculated values are consistent well with the experimental ones.

    更新日期:2019-11-30
  • High-pressure experimental and theoretical study of CO2 solubility in aqueous blends of lysine salts with piperazine as new absorbents
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-30
    Humbul Suleman, Abdulhalim Shah Maulud, Afaf Syalsabila, Muhammad Zubair Shahid, Philip Loldrup Fosbøl

    Vapour-liquid equilibrium of carbon dioxide loaded potassium and sodium l-lysine salts have been investigated in the region of high-pressure and high loadings. The equilibrium solubility of carbon dioxide was measured in separate aqueous l-lysine alkaline salts for a range of temperature (303.15–363.15 K), solution concentrations (1.0–3.0 M) and pressure (95–4204 kPa). In addition to that, solubility of carbon dioxide in blends of both aforementioned amino acid salts with piperazine were investigated. All the studied solutions exhibited an increase in the carbon dioxide loading values with increase in the pressure and had a negative relationship with increase in the temperature and solvent concentration. Furthermore, the experimental data was correlated by the Kent-Eisenberg model. The correlated values shows a good agreement (AAD% of 5.15%) with experimental values. The regressed parameters of the model allows satisfactory estimation of the loadings of carbon dioxide in all studied solutions, for parametric studies. The study shows that l-lysine salts are potential green solvents for the carbon dioxide capture at high pressure.

    更新日期:2019-11-30
  • Protic ionic liquids as constituent of aqueous two-phase system based on acetonitrile: Synthesis, phase diagrams and genipin pre-purification
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-29
    Lídia Cristina Alves Camêlo, Gabriela de Souza Dias Santos, Ranyere Lucena de Souza, Cleide Mara Faria Soares, Jorge Fernando Brandão Pereira, Álvaro Silva Lima

    The aim of this study was to evaluate the formation of aqueous two-phase systems (ATPS) based on different protic ionic liquids (PIL), synthesized using amines, and organic or inorganic acid, and acetonitrile (ACN). The ATPSs are used to pre-purify genipin from genipap (Genipa americana L.). All PILs (purity above 98%) were able to form ATPSs with ACN, the size of the biphasic region being directly dependent on salting-out aptitude of PIL anions and relative hydrophilicity of the corresponding cations. The highest solid–liquid extraction of genipin from genipap was achieved by using aqueous ACN solution at 75% (16.79 ± 0.06 mg g−1 dry raw material) as extractant. After the extraction stage, the ATPS was used as an integrated platform to pre-purify the genipin present in the extract. Three different overall mixture point compositions were tested, and those formed by [MEA][H2Cit] (25 wt%) + ACN (45 wt%) + water (30 wt%) at 298.15 ± 1.00 K and 0.10 ± 0.01 MPa showed the highest selectivity (S = 4.202 ± 0.009) and recovery of genipin in top phase (RTG = 56.74 ± 0.04%), and the purification factor in top phase was 5.9 fold.

    更新日期:2019-11-30
  • Fast methods of Debye-Hückel limiting slopes calculation and low-temperature extrapolation based on IAPWS equation of state of water
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-26
    Alexey L. Voskov, Nikita A. Kovalenko

    An accurate approximation for the Debye-Hückel limiting slopes based on the IAPWS (the International Association for the Properties of Water and Steam) equations for water was proposed. It is valid for T=273.15−523.15K and p=0−100MPa and uses one self-consistent formula and parameters set for all six coefficients. It uses a special extrapolation procedure for values below 273.15 K that is not dependent on equations of state for supercooled water and can be applied down to 173.15 K. The computations took only about 1% of the time that was required for the computations based on original IAPWS equations. Usage of the IAPWS-IF97 (IAPWS Industrial Formulation 1997) equation instead of the IAPWS95 equation for the water density is also discussed. The developed procedure was also applied to other popular equations for Debye-Hückel coefficients (by Archer and Wang and by Bradley and Pitzer). Tabulated IAPWS95 based values for the Debye-Hückel limiting slopes for T=273−723K, p=0−100MPa and their extrapolation down to 173 K are given.

    更新日期:2019-11-26
  • [DCA]-based ionic liquids for the extraction of sulfur and nitrogen compounds from fuels: Activity coefficients at infinite dilution
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-24
    Urszula Domańska, Michał Wlazło, Monika Karpińska

    Some petroleum processes need the removal of low level aromatic-sulfur and nitrogen compounds for many products, which are extremely important according to the new strict environmental regulations to reduce sulfur and nitrogen content compounds in liquid fuels. Thus the new, alternative solvents such as ionic liquids (ILs) have been proposed. ILs reveal a high selectivity and capacity of extraction of sulfur- and nitrogen-compounds from alkanes with little solvent loss during the process. The measurements of activity coefficients γ13∞ at infinite dilution of different solutes in the IL shows the effect of interactions between organic solutes, or water on the interfacial and bulk properties of the IL. The new (3-cyanopropyl)pyridinium dicyanamide, [N–C3CNPy][DCA] and (3-cyanopropyl)methylpyrrolidinium dicyanamide, [N–C3CNMPyr][DCA] were investigated in this work. The data were obtained using the gas-liquid chromatography technique. Measurements were undertaken at six temperatures, in 10 K intervals, in the range of (318.15–368.15) K. The solutes studied included both non-polar and polar compounds, as alkanes, alkenes, alkynes, as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, and esters. The most important solutes used were thiophene, pyridine, and 1-nitropropane. Densities, ρ, measurements for a range of temperatures, T (298.15–368.15) K for the chosen ILs were undertaken at pressure, p = 101 kPa. The gas-liquid partition coefficients, KL at infinite dilution were calculated. The fundamental thermodynamic functions such as partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated from the experimental data measurements to discuss the interaction between solutes and the ILs. The values of selectivity and capacity for three separation cases, viz. heptane/thiophene, heptane/pyridine, and heptane/1-nitropropane were calculated from γ13∞ values and compared to literature data for dicyanamide-based ILs. The Abraham solvation parameter model was presented for all solutes. The obtained results indicated that [N–C3CNPy][DCA] has large selectivity and capacity values for all three of the separation cases studied.

    更新日期:2019-11-26
  • Thermodynamic modeling of gas solubility in aqueous solutions of quaternary ammonium salts with the e-CPA equation of state
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-22
    Li Sun, Xiaodong Liang, Nicolas von Solms, Georgios M. Kontogeorgis

    The study of gas solubility in aqueous electrolyte solutions is important, e.g. for hydrate applications, and it is also a challenging task, as metal halide salts show salting-out effects on gas in water, while some quaternary ammonium salts (QAS) show salting-in effects. This work presents a modeling study of gas solubility in aqueous solutions of several QAS (tetra-n-methyl-ammonium bromide, tetra-n-ethyl-ammonium bromide, tetra-n-propyl-ammonium bromide and tetra-n-butyl ammonium bromide) with the electrolyte Cubic-Plus-Association Equation of State (e-CPA). The ion size and ion-water interaction parameters are obtained by fitting the experimental data of mean ionic activity coefficients and osmotic coefficients of corresponding binary mixtures. The results show that e-CPA can reasonably correlate the mean ionic activity coefficients of QAS in aqueous solutions. The ion-gas interaction parameters are obtained by fitting the experimental data of gas solubility and the results show that e-CPA can correlate the gas solubilities (for nitrogen, carbon dioxide, methane and ethane) reasonably well from a quantitative point of view. For example, e-CPA gives deviations of 9.2% and 5.7% for the solubilities of carbon dioxide and methane in TBAB, respectively. The salting-in and salting-out effects and the influencing factors are also studied.

    更新日期:2019-11-22
  • 更新日期:2019-11-22
  • Corresponding state principle based correlation for the surface tension of carboxylic acids
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-21
    Shangguo Yang, Jianxiang Tian, Hua Jiang

    Motivated by the recent work by G. Di. Nicola et al. [Fluid Phase Equilibria 417 (2016) 229], based on the DIPPR data for carboxylic acids, we here report a corresponding state based correlation for the temperature dependent surface tension of carboxylic acids fluids. Underneath the two reduced quantities defined here, the DIPPR data show a unique trend. It is found that the proposed correlation can be used for different subfamilies of the carboxylic acids, and can describe the DIPPR data with high accuracy with the absolute average deviation (AAD) less than 1% for 14 carboxylic acids, AAD<2% for 20 carboxylic acids, and AAD<5% for all the 29 carboxylic acids.

    更新日期:2019-11-21
  • A PC-SAFT model for hydrocarbons V: Alcohol-hydrocarbon phase behavior with application to petroleum pseudo-components
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-19
    Bennett D. Marshall

    Prediction of alcohol-hydrocarbon phase behavior within a SAFT equation of state is a well-studied topic in the recent literature. Most of these studies focus on the phase behavior of alcohols with n-alkanes, and have demonstrated the successful prediction of non-ideal phase behavior. If the same predictability is to be attained for mixtures of alcohols with aromatic species, there must be a systematic approach to allow for the aromatic cores to receive hydrogen bonds. In this work, we develop a new alcohol parameterization within the PC-SAFT equation of state which is shown to give accurate predictions of alcohol-hydrocarbon phase behavior with both saturated and aromatic hydrocarbons. A major application of alcohol-hydrocarbon phase behavior is the prediction of the phase behavior of alcohol-gasoline blends. In a refinery setting, gasoline will be described by a series of petroleum pseudo-components. In conjunction with the developed alcohol parameterization, we demonstrate the ability of the recently developed EMPETRO characterization scheme to predict the phase behavior of alcohols with petroleum pseudo-components. In a sister publication [Vella J. R. and Marshall B. D., Fuel, 2019] we apply this methodology to predict refinery blending properties of alcohol-gasoline blends such as Reid vapor pressure and ASTM D86 distillation curves.

    更新日期:2019-11-19
  • Speed of sound measurements in deuterium oxide (D2O) at temperatures between (276.97 and 363.15) K and at pressures up to 210 MPa
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-18
    S. Lago, P.A. Giuliano Albo, G. Cavuoto

    This paper presents speed of sound measurements in heavy water (deuterium oxide, D2O) along six isotherms between 276.97 K and 363.15 K for pressures up to 210 MPa using a double pulse-echo method. The experimental apparatus was validated measuring the speed of sound in ordinary water at ambient pressure and at temperatures between 295.5 K and 363.15 K with results found in agreement with values calculated from the reference equation of state for water by Wagner and Pruß within 0.005%. The relative combined expanded uncertainty of our speed of sound measurements, at a confidence level of 95%, is estimated to be less than 0.03% for pressures up to 10 MPa and in the order of 0.05% for pressures up to 210 MPa in the whole investigated temperature range. The speed of sound results have been compared with values calculated from the reference equation for heavy water the IAPS84 Formulation by Hill et al. (1982), and with the prediction of the newly developed equation of state for heavy water by Herrig et al. (2018). The relative deviations of these comparison were found to be consistent with the reference equations within their combined uncertainty. The results presented here were also compared with the most recent data by Wegge et al. and found to be in agreement within 0.05%.

    更新日期:2019-11-19
  • Implementation of the UNIQUAC model in the OpenCalphad software
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-18
    Jing Li, Bo Sundman, Jos Winkelman, Antonis I. Vakis, Francesco Picchioni

    The UNIQUAC model is often used, for example in engineering, to obtain activity coefficients in multicomponent systems, while the CALPHAD method is known for its capability in phase stability assessment and equilibrium calculations. In this work, we combine them by representing the UNIQUAC model according to the CALPHAD method and implementing it in the OpenCalphad software. We explain the harmonization of nomenclature, the handling of the model parameters and the equations and partial derivatives needed for the implementation. The successful implementation is demonstrated with binary and multicomponent phase equilibrium calculations and comparisons with literature data. Additionally we show that the implementation of the UNIQUAC model in the OpenCalphad software allows for the calculation of various thermodynamic properties of the systems considered. The combination provides a convenient way to assess interaction parameters and calculate thermodynamic properties of phase equilibria.

    更新日期:2019-11-19
  • Modeling the solubility of Alkyl Ketene Dimer in supercritical carbon dioxide: Peng-Robinson, group contribution methods, and effect of critical density on solubility predictions
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-18
    Kolawole Adenekan, Brenda Hutton-Prager

    Alkyl Ketene Dimer (AKD) is a sizing agent commonly introduced into cellulose substrates during papermaking to improve its hydrophobicity. High-pressure impregnation of this solute with supercritical carbon dioxide (scCO2) into cellulose and other substrates can achieve excellent hydrophobicity of the substrate, and may be used as an alternative technique to traditional coating (sizing) methods. In this study, the solubility of AKD in scCO2 was modelled using Peng-Robinson equation of state (PR-EOS) with van der Waals mixing rules, and volume-translated PR-EOS (VTPR). Given the unavailability of AKD's experimental critical properties and vapor pressure data, group contribution estimation methods (GCEM) were used to determine these physical constants. Available experimental data from another research group, collected using cloud-point and extraction methods, was used to regress binary interaction parameters and compare the resulting model's capability in predicting solubility. The models for each experimental method predicted crossover pressures within a small range, but fitted the cloud-point experimental data much better than the extraction data, showing good agreement at pressures beyond 15 MPa and all temperatures investigated. The VTPR model showed the least agreement with experimental data. A relative standard deviation of 0.26 was obtained between modelled and experimental data for the cloud-point method, and 0.42 for the extraction method data. The models were confirmed with the Chrastil equation, and strongly demonstrated the linear relationships predicted by this expression. The models additionally predicted a change in temperature dependence around the critical density, with a common linear relationship independent of temperature being observed at densities below the critical value. This newly observed behavior, not predicted by the Chrastil equation, sets the groundwork for further fundamental investigations, while the developed models will assist the design of alternative sizing processes involving AKD and scCO2.

    更新日期:2019-11-18
  • Long-range correlations in the statistical theory of fluid criticality
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-18
    V.N. Bondarev

    Using the approach formulated in the previous papers of the author, a consistent procedure is developed for calculating non-classical asymptotic power terms in the total correlation function hc(r) of a “critical” fluid. Analyzing the Ornstein-Zernike equation with taking account of the contribution ∼hc4(r) in the direct correlation function cc(r) allows us to find, for the first time, the values of transcendental exponents n'=1.73494... and n"=2.26989...which determine the asymptotic terms next to the leading one in hc(r). It is shown that already the simplest approximation based on only two asymptotic terms, ∼r−6/5(it was found earlier) and ∼r−n', leads to the functions hc(r) and cc(r), which agree (at least, qualitatively) with the corresponding correlation functions of the Lennard-Jones fluid (argon) in the near-critical state. The obtained results open a way for consistent theoretical interpretation of the experimental data on the critical characteristics of real substances. Both the theoretical arguments and analysis of published data on the experimentally measured critical exponents of real fluids lead to the conclusion that the known assumption of the similarity of the critical characteristics of the Ising model and the fluid in the vicinity of critical point (the “universality hypothesis”) should be questioned.

    更新日期:2019-11-18
  • Phase equilibrium modeling for methane solubility in aqueous sodium chloride solutions using an association equation of state
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-17
    Wei Xiong, Xiao-Qiang Bian, Yong-Bing Liu

    A new formulation for the fraction of electron acceptor sites of methane (CH4) of cubic-plus-association couple with Huron-Vidal (CPA-HV) model is presented, and a combine rule is used to calculate the cross-associating strength of CH4-water (H2O) binary system. Meanwhile, the interaction parameters (Eij, Eji and F) of CPA-HV model are regressed for CH4–H2O binary and CH4–H2O–NaCl ternary systems. The predictions of CPA-HV model are consistent with a lot of binary and ternary experimental data of these systems. Compared with CPA-vdW and SRK-HV models, the accuracy of CPA-HV model is the best for vapor-liquid equilibria of CH4–H2O system. The average absolute relative deviations of the predicted CH4 solubility in H2O and aqueous sodium chloride solutions for CPA-HV model are respectively 5.84% and 6.91%.

    更新日期:2019-11-18
  • Phase equilibrium for polymer/ionic liquid aqueous two-phase systems
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-15
    Y.P. Jiménez, C. Román Freijeiro, A. Soto, O. Rodríguez

    In this work, the use of ionic liquids as phase-forming components of Aqueous Two-Phase Systems (ATPS) has been evaluated. All ionic liquids used are based on the imidazolium cation, with different alkyl side chains and anions (chloride, bromide, acetate or dicyanamide). As counterpart on the ATPS, a random co-polymer of ethylene oxide and propylene oxide monomers (named EOPO or UCON) was used. Phase diagrams (tie-lines and binodal curves) for a set of UCON/ionic liquid ATPS were measured experimentally at T = (288.15, 298.15 and 308.15 K), using the density and refractive index of the mixtures to obtain the composition of equilibrium phases. The extension of the heterogeneous region increases but the slope of the tie-lines did not change significantly with temperature. Anions had a dramatic effect on the ATPS immiscibility, where acetate produced the largest heterogeneous region and thiocyanate the smallest, following the series OAc− > Cl− > Br− > SCN−. The Chen-NRTL and modified Wilson models were used to correlate the liquid–liquid equilibrium data, but better results were obtained with the Chen-NRTL model.

    更新日期:2019-11-18
  • A neural network correlation for molar density and specific heat of water: Predictions at pressures up to 100 MPa
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-15
    E.B. Melo, E.T. Oliveira, T.D. Martins

    The IAPWS-95 formulation is a set of equations that calculates water properties with high precision. To obtain a certain thermodynamic property, one or more iterative procedures are needed, which demand high computational effort. The aim of this work was to obtain an Artificial Neural Network based equation to predict the IAPWS-95 formulation values of density (ρ) and (Cp) of water in liquid, vapor, and supercritical phases, including the saturation line. Data at temperatures up to 1275 K, and pressures up to 100 MPa were considered. Different sets of input variables were tested and best results were obtained using: temperature, pressure, and speed of sound (used to differentiate liquid from vapor at the saturation line). The network 3-20-15-2 was 99.70% faster than the IAPWS formulation, and presented an overall mean percentage errors of 0.23% and 0.51% for ρ and Cp, respectively, which were lower than those obtained using known correlations.

    更新日期:2019-11-18
  • Isobaric vapor-liquid equilibrium for toluene-methanol system including three ionic liquids with acetate anion at 101.3 kPa
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-15
    Wenxiu Li, Ting Guan, Ying Cao, Yu Zhang, Tao Zhang

    In order to enhance the separation ability of ionic liquid (IL) in the toluene-methanol binary azeotrope, the vapor-liquid equilibrium (VLE) data for the ternary systems of toluene + methanol + IL (1-decyl-3-methylimidazolium acetate [DMIM][OAC], 1-tetradecyl-3-methylimidazolium acetate [C14MIM][OAC] or tri octyl methylammonium acetate [N8,8,8,1][OAC]) were measured at 101.3 kPa. The VLE data were well correlated by the nonrandom two-liquid (NRTL) model. The azeotrope of the toluene-methanol mixture can be fully eliminated when IL content is increased to a specific value. The relative volatility (α12) of toluene to methanol is increased with the increase of [DMIM][OAC] or [C14MIM][OAC], while it is decreased with the increase of [N8,8,8,1][OAC]. The separation ability of [DMIM][OAC] is higher than that of [C14MIM][OAC]. The separation abilities of the three ILs were analyzed with the help of their σ-profiles.

    更新日期:2019-11-18
  • A predictive power sequence equation for vapor pressures of pure organic fluids and partial pressures in multicomponent systems in equilibrium
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-14
    Otto G. Piringer

    The simplified Clausius-Clapeyron equation with the assumption of a constant molar enthalpy of vaporization is not adequate for general applications, despite the desirable need of using only two experimental values for the two integration constants. Therefore many correlations and models of equations of state with more than two necessary empirical constants are used. Here the critical state equation is used as a starting point, with a power sequence as a mathematical model for the estimation of the critical constants for small molecules and for homologous series. With the n-alkanes as reference class for all organic compounds, a reference vapor pressure equation has been defined as function of the relative molecular mass M, which represents principally the correct temperature dependence over the entire liquid state of n-alkanes. With an additional, temperature dependent structural increment U, with the same dimensionless unit as M, a generally applicable vapor pressure equation results for all organic fluids which needs only two specific experimental values. In this investigation principally liquids with freezing point, Tf < 298 K are discussed. The two experimental vapor pressures used are for T1 = 298.15 K and T2 = Tb (boiling point). The predicted values are reliable for the most part of the liquid state. The equation has been validated for alkanes, alkyl-benzenes, 2-ketones, esters, primary alcohols and carboxylic acids by comparing of predicted values with published data of high quality. The increment values for specific functional groups and branching groups can be used for pressure predictions only when the structure or the boiling point is known. An important application of the increments is the prediction of partial pressures in binary mixtures with specific fractions δ of the U-values. The determination of the corresponding δ-values from a set of experimental partial vapor pressures is very easy in comparison with other models. Prediction of partial pressures in multicomponent systems at equilibrium is possible with a good first approximation, without additional empirical constants. Most remarkably, for the application of the developed equation only a small number of easily available empirical parameters are needed as structure increments U and fractions δ of U. The qualitative relation of these parameters to the polarities and other properties of the investigated compounds allow a better understanding of the main reasons for the relative magnitude of vapor pressures and their interactions in mixtures.

    更新日期:2019-11-14
  • Non-equilibrium phase behavior in gas condensate depletion experiments
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-14
    Yang Yang, Zenming Lun, Rui Wang, Wei Hu

    Full diameter core depletion tests are performed in this study to investigate the influence of depletion rate on the production of gas and condensate. Experimental results confirm that the gas recovery of the fast-depletion test is lower than that of the slow-depletion test. On the contrary, without the consideration of the fluid flow in porous media, the condensate recovery of the fast-depletion test is higher than that of the slow-depletion test. Non-equilibrium phase behavior is claimed to explain this abnormal behavior. The non-equilibrium model is adopted in this paper based on the components’ transfer rates between oil and gas phases. In addition, with the consideration of the compositional change in gas-condensate production, a numerical model is built to simulate the depletion process. Based on the comparison between the simulation and experimental results, the influence of non-equilibrium phase behavior on gas-condensate production is analyzed. If the depletion rate is relatively high, the heavy components of the gas-condensate system tend to be produced within the gas phase instead of condensing inside the core due to incomplete vapor-liquid separation. As a result, more condensate is acquired from the fast-depletion test.

    更新日期:2019-11-14
  • 更新日期:2019-11-13
  • The temperature influence on the phase behavior of ionic liquid based aqueous two-phase systems and its extraction efficiency of 2-chlorophenol
    Fluid Phase Equilibr. (IF 2.514) Pub Date : 2019-11-12
    Jifeng Guo, Shuai Xu, Yanlin Qin, Yuliang Li, Xuliang Lin, Chong He, Shuqi Dai

    With the increasing research on the aqueous two-phase systems (ATPS), the ATPS containing ionic liquid (IL) and salt have been widely used in the extraction and purification process. In this work, the partitioning of 2-chlorophenol in novel ATPS composed of n-butylpyridinium trifluoromethanesulfonate and salts (ammonium sulfate, sodium dihydrogen phosphate) is evaluated. Firstly, the cloud point titration method was used to determine the binodal curves data experimentally at four temperatures and atmospheric pressure. And Merchuk equation was used to fit the binodal curves. Then, the gravimetric method was used to initially determine the tie-lines data and the concentration of all the ions in the top and bottom phases were determined by ion chromatography method to study the ion exchange in the ATPS. The reliability of tie-lines was evaluated by Othmer-Tobias and Bancroft equations. Finally, the influence of types of salts and temperature on the phase diagrams were studied carefully. Besides, in order to analyze the application of ATPS in the extraction, the partition coefficient of 2-chlorophenol was calculated at the same total composition while at different temperature. The ATPS formed by n-butylpyridinium trifluoromethanesulfonate, ammonium sulfate, and water at 298.15 K was found to have the maximum amount of partition coefficient and extraction efficiency.

    更新日期:2019-11-13
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