用变阱宽方阱链流体状态方程模拟离子液体相行为

An equation of state (EOS) for square-well chain fluids with variable range (SWCF-VR) developed based on statistical mechanics for chemical association was employed for the calculations of pressure-volume-temperature (pVT) and phase equilibrium of pure ionic liquids (ILs) and their mixtures. The new molecular parameters for 23 ILs were obtained by fitting their experimental density data over a wide temperature and pressure ranges. The molecular parameters of ILs composed of homologous organic cation and an identical anion such as [Cxmim][NTf2] are good linear with respect to their molecular weight, indicating that the molecular pa-rameters of homologous substances, subsequently pVT and vapor-liquid equilibria vapor-liquid equilibria (VLE) can be predicted using the generalized parameter when no experimental data were available. The new set of parameters were satisfactorily used for calculations of the property of solvent and ILs mixture and the solubility of gas in various ILs at low pressure only using one tem-perature-independent binary interaction parameter.     

借助变阱宽方阱链流体状态方程模拟非电解质体系表面张力和粘度(英文)

The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of surface tension and viscosity of common fluids and ionic liquids(ILs).A model of surface tension for multi-component mixtures is presented by combining the SWCF-VR EOS and the scaled particle theory and used to produce the surface tension of binary and ternary mixtures.The predicted surface tensions are in excellent agreement with the experimental data with an overall average absolute relative deviation(AAD)of 0.36%.A method for the calculation of dynamic viscosity of common fluids and ILs at high pressure is presented by combining Eyring’s rate theory of viscosity and the SWCF-VR EOS.The calculated viscosities are in good agreement with the experimental data with the overall AAD of 1.44% for 14 fluids in 84 cases.The salient feature is that the molecular parameters used in these models are self-consistent and can be applied to calculate different thermodynamic properties such as pVT,vapor-liquid equilibrium,caloric properties,surface tension,and viscosity.     

Salting-out effect of ionic liquids on isobaric vapor-liquid equilibrium of acetonitrile-water system☆

This paper presents the vapor–liquid equilibrium (VLE) data of acetonitrile–water system containing ionic liquids (ILs) at atmospheric pressure (101.3 kPa). Since ionic liquids dissociate into anions and cations, the VLE data for the acetonitrile+water+ILs systems are correlated by salt effect models, Furter model and improved Furter model. The overall average relative deviation of Furter model and improved Furter model is 5.43%and 4.68%, respectively. Thus the salt effect models are applicable for the correlation of IL containing systems. The salting-out effect theory can be used to explain the change of relative volatility of acetonitrile–water system.     

单乙醇胺和二乙醇胺甲酸盐离子液体对水、甲醇和乙醇挥发度的影响(英文)

Vapor pressures were measured for six binary systems containing water, ethanol, or methanol with one of the two ionic liquids （ILs） at different component concentrations and temperatures using a quasi-static ebulliometer, with the ILs mono-ethanolammonium formate （[HMEA][HCOO]） and di-ethanolammonium formate （[HDEA][HCOO]）. The vapor pressures of the IL-containing binary systems are well correlated using the NRTL model with an overall average absolute relative deviation （AARD） of 0.0062. The effect of ILs on the vapor pressure depression of sol-vents at 0.050 mole fraction of IL is that [HDEA][HCOO]〉[HMEA][HCOO], and the vapor pressure lowering de-gree follows the order of water〉methanol〉ethanol. Further, the activity coefficients of three solvents （viz. water, ethanol, and methanol） for the binary systems{solvent （1）＋IL （2）}predicted based on the fitted NRTL parameters at T=333.15 K indicate that the two ILs generate a negative deviation from Raoult’s law for water and methanol and a positive deviation for ethanol to a varying degree, change the relative volatility of a solvent. [HMEA][HCOO] may be a promising entrainer to efficiently separate ethanol aqueous solutions by special rectification.     

离子液体[C4mim][PF6]与N, N-二甲基甲酰胺二元混合物在298.15 K～318.15 K的密度和粘度

Viscosities and densities for 1-butyl-3-methylimidazolium hexafluorophosphate （[C4mim][PF6]） and N, N-dimethylformamide （DMF） binary mixtures have been measured at the temperature range from 293.15 K to 318.15 K. It is shown that the viscosities and densities decrease monotonously with temperature and the content of DMF. Various correlation methods including Arrhenius-like equation, Sedclon et al.＇s equation, Redlich-Kister equation with four parameters, and other empirical equations were applied to evaluate these experimental data. A model based on an equation of state Ior estimating the viscosity of mixtures containing ionic liquids were proposed by coupling with the excess Gibbs free energy model of viscosity, which can synchronously calculate the viscosity and the molar volume. The results show that the model gives a deviation of 8.29% for the viscosity, and a deviation of 1.05% for the molar volume when only one temperature-independent adjustable parameter is adopted. The correlation accuracy is further improved when two parameters or one temperature-dependent parameter is used.     

Effect of methylimidazolium-based ionic liquids on vapor–liquid equilibrium behavior of tert-butyl alcohol + water azeotropic mixture at 101.3 kPa

Three ionic liquids(ILs),1-ethyl-3-methylimidazolium bromine([EMIM]Br),1-butyl-3-methylimidazolium bromine([BMIM]Br),and 1-hexyl-3-methylimidazolium bromine([HMIM]Br),were used as the solvent for separation of {tert-butyl alcohol(TBA)+ water} azeotrope.Vapor–liquid equilibrium(VLE)data for {TBA + water + IL}ternary systems were measured at 101.3 k Pa.The results indicate that all the three ILs produce an obvious effect on the VLE behavior of {TBA + water} system and eliminate the azeotropy in the whole concentration range.[EMIM]Br is the best solvent for the separation of {TBA + water} system by extractive distillation among the three ILs.The experimental VLE data for the ternary systems are correlated with the NRTL model equation with good correlations.Explanations are given with activity coefficients of water and TBA,and the experimental VLE-temperature data for {TBA or water + IL} binary systems.     

运用人工神经网络关联二元混合物中气液相平衡

In this paper, a back propagation artificial neural network （BP-ANN） model is presented for the simultaneous estimation of vapour liquid equilibria （VLE） of four binary systems viz chlorodifluoromethan-carbondioxide, trifluoromethan-carbondioxide, carbondisulfied-trifluoromethan and carbondisulfied-chlorodifluoromethan. VLE data of the systems were taken from the literature for wide ranges of temperature （222.04-343.23K） and pressure （0.105 to 7.46MPa）. BP-ANN trained by the Levenberg-Marquardt algorithm in the MATLAB neural network toolbox was used for building and optimizing the model. It is shown that the established model could estimate the VLE with satisfactory precision and accuracy for the four systems with the root mean square error in the range of 0.054-0.119. Predictions using BP-ANN were compared with the conventional Redlich-Kwang-Soave （RKS） equation of state, suggesting that BP-ANN has better ability in estimation as compared with the RKS equation （the root mean square error in the range of 0.115-0.1546）.     

一氧化碳在苯酚+乙醇中的溶解度测量和关联

The solubility of carbon monoxide in phenol＋ethanol mixed solvents at elevated pressures is reported in this article. The experimental results revealed the influence of pressure on the solubility of CO in phenol＋ethanol mixtures. These mixtures are a poorer solvent for carbon monoxide. The solubility of CO is a linear function of pressure, and the extended Henry＇s constants were presented at different concentrations of phenol. The cubic Soave-Redlich-Kwong equation of state was used to correlate the experimental gas liquid equilibrium data and to predict the solubility of CO. At the same time, the binary interaction parameters, kO, for CO-phenol, CO-ethanol and phenol-ethanol systems were estimated by fitting experimental GLE data at 303.15 K and at 2.0-9.0 MPa. Hence, a model was suggested for the solubility of CO in phenol＋ethanol mixed solvents. The agreement between experimental and calculated solubilities with the proposed model was rather satisfactory.     

EOS状态下基于多相流有规栅格理论的水-碳氢化合物两相体系的临界轨迹关系

Quantitative representation of complicated behavior of fluid mixtures in the critical region by any of equation-of-state theories remains as a difficults thermodynamic topics to date.In the present work,a computational efforts were made for representing various types of critical loci of binary water with hydrocarbon systems showing Type Ⅱ and Type Ⅲ phase behavior by an elementary equation of state[called multi-fluid nonrandom lattice fluid EOS(MF-NLF EOS)]based on the lattice statistical mechanical theory.The model EOS requires two molecular parameters which representing molecular size and interaction energy for a pure component and single adjustable interaction energy parameter for binary mixtures.Critical temperature and pressure data were used to obtain molecular size parameter and vapor pressure data were used to obtain interaction energy parameter.The MF-NLF EOS model adapted in the present study correlated quantitatively well the critical loci of various binary water with hydrocarbon systems.     

Prediction of critical temperature,critical pressure and acentric factor of some ionic liquids using Patel-Teja equation of state based on genetic algorithm

Critical properties and acentric factor (ω) of 31 ionic liquids (ILs) were obtained by using vapor-liquid equilibrium data of solvent+IL consisting of P-T and P-x experimental data, based on three-parameter Patel-Teja equation of state and genetic algorithm. Optimized P _c , T _c and ω of ILs with Peng-Robinson equation of state (PR EoS) were used to model the behavior of phase equilibria of solvent+IL. Due to lack of experimental data for optimized properties, the validation was done by comparing them to the results in the literature. In each comparison the average absolute percent deviation (AAPD) for optimized properties was based on P-T experimental data, with PR EoS was minimum. For more confidence in the correctness of optimized properties, the behavior of phase equilibria of two new mixtures (i.e., water+emimDMP and methanol+emimDMP), the density and vapor pressure of some pure ILs were predicted by PR EoS, which the prediction of this EoS was satisfactory.     

Modeling of CO2 Solubility in Selected Imidazolium-Based Ionic Liquids

This study explores the use of COSMO-RS model and Peng-Robinson (PR) equation of state (EoS) to predict the solubility of carbon dioxide (CO₂) in specific ionic liquids (ILs). COSMO-RS was employed to estimate of CO₂ solubility at atmospheric pressure in eight imidazolium-based ILs resulting from the combination of ethyl, butyl, hexyl, and octyl-imidazolium cations with two anions: bis(trifluoromethylsulfonyl)imide ([Tf₂N]) and Trifluoromethanesulfonate ([TFO]). The results indicated relatively acceptable qualitative consistency between the experimental and predicted values. The PR EoS was employed at high pressure by tuning the interaction parameters to fit the experimental data reported in the literature. The model demonstrated excellent accuracy in predicting the solubility of CO₂ at pressure values less than the critical pressure of CO₂; however, at higher pressures, the calculated solubility diverged from the experimental values. Furthermore, the type of anion and cation used in the IL affected the performance of the PR EoS.     

Critical properties and acentric factors of ionic liquids

Since most ionic liquids (ILs) decompose before reaching their critical state, the experimental measurement of their critical properties are not possible. In this study, the critical temperatures, critical pressures and acentric factors of ten commonly investigated ILs were determined by making an optimum fit of the calculated vapor-liquid equilibrium data of binary mixtures of CO₂+IL to the experimental values found in literature. For this purpose, the Peng-Robinson equation of state (PR EoS) and the differential evolution optimization method were used. The ILs considered were 1-ethyl-3-methylimidazolium hexafluorophosphate ([emim][PF₆]), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([emim][Tf₂N]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([bmim][Tf₂N]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim][BF₄]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF₆]), 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([hmim][Tf₂N]), 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF₄]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF₆]). To evaluate the ability of the determined parameters in predicting the phase behavior of systems other than the systems that were used for parameter optimization, both sets of parameters obtained in this work and that of Valderrama et al. were used to predict bubble-point pressures of CHF₃+[bmim][PF₆] (by using the PR EoS and the Soave-Redlich-Kwong equation of state. The bubble-point pressures of CO₂+IL systems optimized in this study by the PR EoS were also determined using the Soave-Redlich-Kwong equation of state (SRK EoS). In addition, liquid densities of pure ILs were predicted using a generalized correlation proposed by Valderrama and Abu-Shark. In all cases, the various predicted properties of these ten ILs, were in better agreement with the experimental data, using the critical properties and acentric factor obtained in this study, compared to the values suggested by Valderrama et al.     

基于黏滞球模型的CPA状态方程应用于醇胺系统相平衡的计算

考虑到醇胺及其混合物中分子间存在缔合作用的事实,结合立方型PR状态方程,通过引入基于黏滞球模型(SSM)发展起来的缔合流体的分子热力学模型,建立了一个新的CPA(cubic-plus-association)状态方程,即CPA-SSM,并将方程应用到醇胺系统相平衡的计算中。通过关联对比温度0.55～0.90范围下醇胺流体的实验饱和蒸气压和液相体积得到了8种醇胺流体的分子参数。结果表明,CPA-SSM方程可满意地计算出醇胺饱和蒸气压和液体密度,总平均误差分别只有0.57%和1.80%。对醇胺混合物,无论是恒压还是恒温系统,只需引入一个与温度无关的可调参数,CPA-SSM方程即可满意关联二元系统的汽液平衡数据,并可进一步预测多元混合物的汽液平衡。     

Application of PSRK for Process Design

A survey about the current status and potential of the predictive Soave-Redlich-Kwong (PSRK) group contribution equation of state (EoS) is given. The PSRK method combines the SRK EoS with the UNIFAC group contribution model by the PSRK mixing rule. The availability of a large number of interaction parameters between UNIFAC and new PSRK main groups allows calculating the phase equilibrium behavior and other thermodynamic quantities for various kinds of systems even with strong electrolytes. Different fields of application are discussed: the prediction of gas solubilities in asymmetric systems, the air solubility calculated for mixed solvents, the removal of H₂S from natural gas by predicting the physical absorption, and the calculation of the enthalpy effects of absorption processes with pressure and temperature.     

Application of PSRK for Process Design

A survey about the current status and potential of the predictive Soave-Redlich-Kwong (PSRK) group contribution equation of state (EoS) is given. The PSRK method combines the SRK EoS with the UNIFAC group contribution model by the PSRK mixing rule. The availability of a large number of interaction parameters between UNIFAC and new PSRK main groups allows calculating the phase equilibrium behavior and other thermodynamic quantities for various kinds of systems even with strong electrolytes. Different fields of application are discussed: the prediction of gas solubilities in asymmetric systems, the air solubility calculated for mixed solvents, the removal of H₂S from natural gas by predicting the physical absorption, and the calculation of the enthalpy effects of absorption processes with pressure and temperature.     

Measurement and correlation of the isobaric vapor-liquid equilibrium for mixtures of alcohol+ketone systems at atmospheric pressure

Vapor-liquid equilibrium (VLE) for binary mixtures composed of ethanol+methyl isobutyl ketone, 1-butanol+ methyl ethyl ketone, and 1-butanol+methyl propyl ketone systems was measured using a circulation type equilibrium apparatus at atmospheric pressure. The measured data and literature data for alcohol and ketone systems have been correlated by the UNIversal Quasi-Chemical (UNIQUAC) model with two binary interaction parameters and the non-random lattice fluid equation of state with hydrogen bonding equation of state (NLF-HB EoS) using a single binary interaction parameter. For the NLF-HB EoS calculations, the numbers of proton acceptor for ketones were adjusted between 0 and 1. The calculation results with the NLF-HB EoS are better than those with the UNIQUAC model.     

Partition Behavior of Drug Molecules in Cholinium-Based Ionic Liquids

In this paper, a series of ionic liquids (ILs) contains cholinium as cations were prepared. These ILs were used as extractants to separate some model drug molecules. The partition coefficients of these drug molecules between ILs and aqueous solutions were determined. Furthermore, the influence of different extraction parameters was investigated: volume ratio, equilibrium time, pH values, temperature, and ILs structure. It is shown that these ILs are highly effective materials for the extraction of drug molecules. The results imply that these ILs may have potential in drug extraction or separation as a new type of media.     

Extension of Valderrama-Patel-Teja equation of state to modelling single and mixed electrolyte solutions

The Valderrama modification of Patel-Teja equation of state (VPT EoS) has been extended to predicting fluid phase equilibria in the presence of single and mixed electrolyte solutions at high-pressure conditions. Salts have been introduced as components in the EoS by calculating their EoS parameters from corresponding cation and anion parameters. A non-density dependent mixing rule is used for calculating a, b, and c parameters of the EoS. The inclusion of salts in the EoS resulted in the omission of the Debye-Hückel electrostatic contribution term in the fugacity coefficient calculations. Water-salt binary interaction parameters (BIPs) are optimised using freezing point depression and boiling point elevation data of aqueous electrolyte solutions. Gas solubility data in aqueous electrolyte solution are used for optimising salt-gas BIPs. The predictions of the model have been compared with independent experimental data, demonstrating the reliability of the approach.