On the thermodynamics of concentrated strong electrolytes aqueous solutions the system NaNO3—NaCl—H2O

A simple analytical function is proposed for the calculation of molar excess Gibbs energy of binary solutions of strong electrolytes in water. Empirical parameters can be easily determined from experimental data reported in the literature. The treatment is extended to ternary solutions and to solid liquid equilibria using an empirical equation. Absence of solid solutions is assumed. The correlations are applied to the common ion ternary system NaNO₃-NaCl-H₂O in the temperature range from 0 to 100°C. Predictions of activity coefficients of the binary systems and saturation curves of the ternary system are in good agreement with experimental data.     

蛋白质-磷酸钾-聚乙二醇双水相体系热力学研究

建立了由蛋白质、磷酸氢二钾、磷酸二氢钾、聚乙二醇所组成的双水相体系的平衡浓度分析测定方法,实验测定了6种蛋白质分子在25℃下的液液平衡分配数据,共23组.将Baskir等的吸附晶格模型和Pitzer的长程静电项相结合,扩展用于含电解质-高聚物双水相体系的热力学计算,仅用7组实验数据进行关联,得到2个吸附能参数,预测了其它16组蛋白质分配系数,结果满意。并提出了蛋白质分配系数与双水相成相物质在两相间浓度差的经验关系式。     

非电解质水溶液的粘度方程

在Eyring的液体粘性流动模型基础上,根据Rother等的假定和Shealy与Sand ler的水溶液过量自由焓溶质聚集模型,导出了一个双参数非电解质水溶液的粘度模型。利用该模型可由二元水溶液的2个模型参数预测多元水溶液的粘度。用该模型计算了6个体系391个不同温度和组成的二元水溶液和3个体系164个不同温度和组成的三元水溶液的粘度,计算值与实验值的总平均相对偏差分别为1.732%和2.977%,计算值与实验数据吻合很好。     

Modelling of direct-contact evaporation using a simultaneous heat and multicomponent mass-transfer model for superheated bubbles

A recently developed model for coupled heat and mass transfer in binary systems during the formation and ascension of superheated bubbles was extended to a multicomponent system comprising N volatile species. The model allows variable properties and bubble radius changes, assuming diffusive mass fluxes to be properly described by Fick's law. Experimental direct-contact evaporation tests were conducted with ethyl acetate aqueous solutions to provide data for assessing the developed model. In addition, the model was tested against available literature data for an air-stripper. In both cases, a good agreement between simulation and experimental results was verified.     

有机物水溶液导热系数的关联

根据对有机物水溶液导热系数影响因素的分析,在Horvath液体导热系数关系式的基础上,导出了估算有机物水溶液导热系数的计算模型;利用该模型计算了14个体系中447个数据点的不同温度和组成的二元水溶液导热系数;结果表明,计算值与实验数据吻合很好,其与实验值的总平均相对偏差为1.03％,计算准确性优于文献方法。本文计算方法简单方便,只需知道水溶液各组分的临界温度、临界体积和导热系数数据,就可以直接预测各种温度和组成的有机物水溶液混合物的导热系数。     

Measurement and prediction of gas hydrate and hydrated salt equilibria in aqueous ethylene glycol and electrolyte solutions

A recently developed method in modelling electrolyte solutions is extended to include phase behaviour of aqueous solutions containing hydrated salts (e.g., calcium chloride) and organic hydrate inhibitors (e.g., ethylene glycol). A novel salt precipitation model applicable to various hydrated salts is presented. The precipitation model takes into account various precipitates of hydrated salts over a wide range of temperature (i.e., -20-120 ^°C). Due to lack of the required experimental data in the literature, new experimental data have been generated. These data, which have been used in determining the binary interaction parameters between salts and organic inhibitors, include; freezing point depression, boiling point elevation, and salt solubility in the aqueous solutions containing salts and organic inhibitors. The extended thermodynamic model is capable of predicting complex vapour-liquid-solid equilibria (VLSE) for aqueous electrolytes and/or organic inhibitor solutions over a wide range of pressure, temperature and inhibitor concentration.In addition, in order to establish the effect of a combination of salts and organic inhibitors on the locus of incipient hydrate-liquid water-vapour (H-L_W-V) curve, reliable equilibrium data have been generated for one quaternary system, methane/water/calcium chloride/ ethylene glycol at pressures up to 50 MPa. These data along with various independent literature data are used to validate the predictive capabilities of the model for phase behaviour and hydrate equilibria. Good agreement between experimental data and predictions is observed, demonstrating the reliability of the developed model.     

On the modelling of multicomponent acid extraction with long-chain aliphatic amines

The solvent extraction of phosphoric, hydrochloric, sulphuric, hydrofluosilicic and hydrofluoric acids with long-chain aliphatic amins is modelled. Pure acid equilibria are based on existing isotherms or calculated extraction constants when only experimental data are available. For binary mixtures binary combinations of acid complexes are added. In the aqueous phase Bromley's model for electrolytes is used for calculation of ionic activity coefficients and the appropriate association/dissociation equilibria taken into account for calculation of ionic strength. For the organic phase an empirical model for the non-ideal behaviour of phosphoric acid is used. For multicomponent mixtures at low acid concentrations the model calculates the extraction of phosphoric, hydrochloric and sulphuric acid almost quantitatively. For hydrofluosilicic and hydrofluoric acid the calculations are less precise and further information is needed about the different fluoride exchange equilibria involved.     

含盐溶液汽液平衡预测

本文提出一种新的预测含盐溶液汽液平衡的方法。对Pitzer(1980年)模型进行扩展后,将其简化成单参数形式,推广至多元电解质溶液;经过适当假定,得到计算含盐挥发性强电解质和水体系及含盐水醇体系的活度系数公式,这些公式仅含有二元相互作用参数;由二元溶液的活度关联出参数后,可用于含盐体系各温度下汽液平衡的预测。关联了四十个二元电解质水溶液及七个电解质甲醇溶液298.15K时的简化Pitzer方程的单参数;用以推算六个水盐体系和二个甲醇盐体系在320-403K的蒸汽压,得到满意的结果,182个数据点的平均偏差小于0.65kPa;用以预测五个不同类型的含盐三元体系的等温、等压汽液平衡,所得的平均偏差对于汽相组成、沸点、压力分别为0.015、1K、1.92kPa。     

1-氨丙基-3-甲基咪唑溴盐水溶液的汽液相平衡

1-氨丙基-3-甲基咪唑溴盐([APMIm][Br])是一种对CO₂有良好吸收性能的功能型离子液体,在工业中可采用水溶液来实现高效能的吸收和解吸循环过程,因此对其水溶液特性的研究至关重要。对[APMIm][Br]水溶液在中低温度下的汽液相平衡进行了测量,获得可靠的实验数据,从而揭示其水溶液特性。实验温度范围为278.15～348.15 K,[APMIm][Br]在水溶液中质量分数分别为10.0%、20.3%、29.5%、40.0%、57.5%、75.3%、84.0%、88.9%、90.9%。考虑了低温下离子液体分子在水溶液中的强缔合特性,采用带缔合惰化因子的离子液体水溶液活度模型对实验数据进行了拟合,实验值与计算结果符合很好,平均相对误差为2.15%。     

Correlation of the mean activity coefficient of aqueous electrolyte solutions using an equation of state

Accurate calculation of thermodynamic properties of electrolyte solution is essential in the design and optimization of many processes in chemical industries.A new electrolyte equation of state is developed for aqueous electrolyte solutions.The Carnahan–Starling repulsive model and an attractive term based on square-well potential are adopted to represent the short range interaction of ionic and molecular species in the new electrolyte EOS.The long range interaction of ionic species is expressed by a simplified version of Mean Spherical Approximation theory(MSA).The new equation of state also contains a Born term for charging free energy of ions.Three adjustable parameters of new e EOS per each electrolyte solution are size parameter,square-well potential depth and square-well potential interaction range.The new e EOS is applied for correlation of mean activity coefficient and prediction of osmotic coefficient of various strong aqueous electrolyte solutions at 25 °C and 0.1 MPa.In addition,the extension of the new e EOS for correlation of mean activity coefficient and solution density of a few aqueous electrolytes at temperature range of 0 to 100 °C is carried out.     

Studies of association effects in adsorption from multicomponent solutions on solids

The adsorption from multicomponent solutions on solids involving heterogeneity effects and association in the bulk phase is discussed. Two theoretical models are proposed to describe the association of the bulk solution. To consider the influence of both factors on the adsorption equilibrium, i.e. heterogeneity and association effects, the illustrative model calculations are performed. The proposed equations are examined by using the experimental data of n-butanol adsorption from binary hydrocarbon solutions on silica gel.     

Multicomponent sorption kinetics of ethane and propane in activated carbon: simultaneous adsorption

Extensive experimental data of binary adsorption kinetics of ethane and propane onto Ajax activated carbon are collected by using a 'differential adsorption bed' over a range of particle sizes and shapes, bulk concentrations and temperatures. A multicomponent model incorporating macropore, surface and micropore diffusion mechanisms recently proposed by Hu and Do (Chem Eng Sci (in press)) is used to predict the binary adsorption dynamic data by using information of single-component isotherms and dynamics. The multicomponent adsorption equilibrium is calculated by using the ideal adsorbed solution theory (IAST), with the single-component isotherm described by a Unilan equation. The model is found to describe the binary adsorption kinetics well and in particular it accurately predicts the degree of the overshoot of the fast-diffusing/less-strongly adsorbed species.     

MULTICOMPONENT TRANSPORT OF ELECTROLYTES THROUGH CELLULOSE ACETATE MEMBRANES

A multicomponent transport model is presented to describe the rejection components of electrolyte systems by cellulose acetate reverse osmosis membranes. Comparison of the model with the experimental results obtained with NaCl-CaCl₂-H₂O solutions shows good agreement. It was observed that the presence of CaCl₂ can reduce drastically the rejection of NaCl in this multicomponent system and even cause 'negative rejection' in certain cases. The results of this study will be helpful in better understanding, predicting and controlling the operation of reverse osmosis desalination plants that process multicomponent feeds where interactions among the electrolytes present can affect the performance of the membranes used     

Competitive adsorption of phenol and resorcinol onto rice husk ash

The present study deals with the adsorptive removal of phenol and resorcinol from aqueous solution onto rice husk ash. The competitive adsorption equilibrium of the binary mixtures (phenol/resorcinol) was determined by conducting batch experiments with initial concentration varying in the range of 50 to 1000 mg/L. In order to evaluate multicomponent adsorption isotherm parameters, individual adsorption equilibrium studies were also carried out. Langmuir, Freundlich and Redlich-Peterson equilibrium isotherm models were used for single compound equilibrium sorption data modeling. All three models almost similar fit for single compound equilibrium data. Binary equilibrium adsorption data and the parameter evaluated from single adsorption data were fitted to various multicomponent isotherm models by minimizing the sum of square of error. The extended Langmuir model gave the better fit to the experimental adsorption data of phenol and resorcinol from binary systems onto rice husk ash. It seems that both phenol and resorcinol compete for the same adsorption sites on rice husk ash. The net interactive effect of phenol and resorcinol on the adsorption of resorcinol by rice husk ash was found to be antagonistic.     

基于共存理论的二元系强电解质水溶液质量作用浓度通用热力学模型

利用离子-分子共存理论建立了可计算强电解质水溶液组元质量作用浓度的热力学通用模型. 以KCl-H2O, CsCl-H2O, NaCl-H2O及BaCl2-H2O二元系为示例,计算了上述4个二元系在温度为298.15 K、质量摩尔浓度在0.2 mol/kg到饱和浓度范围内的组元质量作用浓度. 热力学模型计算的以纯物质为标准态、以摩尔分数为浓度单位的组元质量作用浓度经过转换后,与文献报道的以无限稀为标准态、以质量摩尔浓度为浓度单位的组元活度可良好吻合. 这说明本工作建立的强电解质水溶液的质量作用浓度热力学模型可用于预测组元活度,基于强电解质水溶液中存在离子和分子结构的推断是合理的,质量作用浓度在计算的组元浓度范围内遵守质量作用定律.     

STRIPPING OF AMMONIA FROM AQUEOUS SOLUTIONS OF AMINO ACIDS AND INORGANIC IONS

The stripping of ammonia from aqueous solutions of amino acids and strong electrolytes has been investigated both experimentally and theoretically. The experiments have been carried out in an isothermal stirred semibatch stripper. A good agreement between experimental data and model predictions has been obtained for all the examined operating conditions. The model accounts for all dissociation equilibria while it assumes ideal behavior for the liquid phase. It does not include any adjustable parameter, and so it can be readily extended to various systems of practical interest, such as those involved in the treatment of side-streams arising in the production of amino acids     

含盐聚电解质溶液的分子热力学模型

A molecular thermodynamic model of polyelectrolyte developed previously was extended to polyelectrolyte solutions with added salts.Thermodynamic properties,such as activity coefficients of polyelectrolytes or added salts and osmotic coefficients of solvent, of a number of aqueous mixtures of polyelectrolytes and salts are analyzed with the proposed model.Successful correlation is obtained in the range of moderate or higher polyion concentration.For the same sample,thermodynamic properties of polyelectrolytes with and without simple electrolytes can be predicted mutually using parameters from regression data.     

非缓冲体系中性氨基酸的离子交换平衡

研究了非缓冲体系中性氨基酸在７３２型强酸性阳离子交换树脂上的离子交换平衡，并提出了平衡模型。该理论模型考虑了氨基酸的两性弱解离性质和树脂能团的能量非均一性，可以很好地关联氨基酸与Ｈ＾＋的二元离子交换平衡，并且通过两个二元体系ＶＡＬ／Ｈ＾＋和Ｎａ＾＋／Ｈ＾＋的平衡参数成功地预测了三元体系ＶＡＬ／Ｎａ＾＋／Ｈ＾＋的平衡关系，表明该模型可以描述非缓冲体系中性氨基酸的多元离子交换平衡。     

Ion-Exchange Equilibrium of Ca2+, Mg2+, K+, Na+, and H+ Ions on Amberlite IR-120: Experimental Determination and Theoretical Prediction of the Ternary and Quaternary Equilibrium Data

Abstract

A study of the cation-exchange equilibria between Amberlite IR-120 resin and aqueous solutions of calcium, magnesium, potassium, and sodium chlorides and hydrochloric acid has been made. Experiments were carried out at 283, 303, and 323 K with solutions having total cation concentrations of approximately 0.1, 0.3, and 0.5 N. Experimental data for the ion-exchange equilibria of the ternary and quaternary systems are reported. These systems exhibit nonideal characteristics in both phases. The predictions have been based on the reaction equilibrium constants and correlations for the activity coefficients in both phases. A model which allows the prediction of multicomponent ion-exchange equilibria from binary data has been developed. Predictions of ternary and quaternary systems based solely on the binary data are in good agreement with the experimental results.