电解质溶液热力学新进展

从应用角度对电解质溶液理论、活度系数半经验模型等方面的研究现状和进展作了综述。认为电解质溶液理论在描述其非理想性时，必须同时考虑带电粒子的长程静电作用、所有粒子间的短程推斥作用和离子的溶剂化作用以及这些作用随温度改变的普遍化关系，以正确反映复杂的多元电解质溶液在宽阔温度范围和浓度区域内的变化规律。     

电解质溶液的分子热力学模型

本文以扰动理论为基础建立了含极性组分和电解质的混合物的状态方程.混合物的Helmholtz能由硬球、静电和吸引项三部分组成.对于无电解质的混合物,本状态方程还原成Hu等近期开发的方程.用Bromley、Meissner、pitzer、Chen和本文摸型对25个二元电解质水溶液(最高浓度达20mol/kg)298.15K时的离子平均活度系数进行了关联,本文模型的精度最高.另外,用298.15K回归出的参数对其它温度下的离子平均活度系数进行了预测,结果表明模型参数与温度的关系较小.     

电解质溶液的粘性电解质模型及其应用

在平均球近似理论的基础上引入离子事项和短程作用力项,建立了粘性电解质模型。离子间导入粘性屏蔽作用。阴离子取Ｐａｕｌｉｎｇ晶体直径,阳离子直径和能量参数由参数估计求得。对１６种碱金属卤化物水溶液的活度系数进行模拟计算,与实验数据比较,误差普遍小于３％,满足工程设计的需要。     

聚电解质溶液的分子热力学模型

聚电解质溶液的分子热力学模型姜建文刘洪来胡英（华东理工大学化学系上海２００２３７）自然界、生物体中的许多物质,诸如核酸、蛋白质等均为聚电解质溶液。聚电解质溶液具有高分子溶液的特性,同时由于其中的聚离子带有相当强的电荷,这使得聚电解质溶液的许多性质都与...     

电解质溶液活度系数的计算方法

本文详细讨论了电解质活度系数的计算方法。     

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.     

初级的强电解质水溶液热力学模型

提出了1个电解质溶液的热力学模型,它由两步组成,即电解质与溶剂的混合和电解质在溶剂中的电离.据此,导得了电解质离子的平均活度系数和溶剂（水）的渗透系数方程.并能方便地推广到混合电解质溶液.用实验数据广泛检验结果表明,这个模型能很好地适用于较高浓度下的强电解质溶液.     

电解质溶液热力学进展

本文从工程应用的角度出发,综述了近年来电解质溶液热力学的理论、活度系数的半经验模型及各类相平衡计算方法。讨论了化工界较为关心的含盐溶液汽液平衡关联和预测的进展问题。     

存在反应的电解质溶液相平衡研究

从应用的角度出发,对电解质溶液模型、相平衡计算的现状与发展进行了简要的回顾,并系统地介绍和讨论了作者在这方面的工作。指出对P itzer模型和作者提出的电解质溶液水化平衡模型建立各自相应的普遍化温度关系,结合所提出的固液平衡级计算方法,可以预测工业过程所涉及的高温、高压、高浓度范围内复杂体系的热力学性质,解决此类过程集成模拟优化的瓶颈问题。此外,还介绍了离子选择性电极测定弱电解质体系热力学的方法。     

Modeling for mean ion activity coefficient of strong electrolyte system with new boundary conditions and ion-size parameters

A rigorous approach is proposed to model the mean ion activity coefficient for strong electrolyte systems using the Poisson–Boltzmann equation. An effective screening radius similar to the Debye decay length is introduced to define the local composition and new boundary conditions for the central ion. The crystallographic ion size is also considered in the activity coefficient expressions derived and non-electrostatic contributions are neglected. The model is presented for aqueous strong electrolytes and compared with the classical Debye–Hückel (DH) limiting law for dilute solutions. The radial distribution function is compared with the DH and Monte Carlo studies. The mean ion activity coefficients are calculated for 1:1 aqueous solutions containing strong electrolytes composed of alkali halides. The individual ion activity coefficients and mean ion activity coefficients in mixed sol-vents are predicted with the new equations.     

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.     

A new model in correlating and calculating the solid–liquid equilibrium of salt–water systems

In this work, a new activity coefficient model was deduced for the correlation of solid–liquid equilibrium(SLE) in electrolyte solutions. The new excess Gibbs energy equation for SLE contains two parts: the single electrolyte item and the mixed electrolyte item. Then a new hypothesis for the reference state of activity coefficients was proposed in the work. Literature data for single electrolyte solution and mixed electrolyte solution systems,with temperature spanning from 273.15 to 373.15 K, were successfully correlated using the developed model.     

A predictive thermodynamic model for the Brazilian gasoline

In Brazil, as in many other countries, the fuel quality control is made according to standard assays, which depend on some of the fuel properties, such as specific gravity, Reid vapor pressure and distillation curve. These properties are intimately related to the fuel composition and their prediction relies on the knowledge of its components characteristics. In Brazil, 25% (v/v) of anhydrous ethanol is added to the mixture of hydrocarbons that is usually called gasoline, according to the local regulations. In this work, the composition of the gasoline was obtained by gas chromatography as a small series of pseudo-components. Given the gasoline composition, its volatility properties and specific gravity were calculated using the Peng-Robinson equation of state with the Fisher-Gmehling mixing rule. The model provided excellent predictions for specific gravity, Reid vapor pressure and most of the distillation curve. However, important deviations are observed at the end of the distillation curve (90+%). These deviations are due to chemical alterations of the fuel caused by the high temperatures occurring at the end of the distillation curve. The model, as proposed, is efficient to forecast the fuel properties; as a consequence, it can be applied as a tool in the study of gasoline formulations and as an alternative tool in quality control.     

Prediction of thermodynamic properties of aqueous electrolyte solutions using equation of state

In this study, a predictive model is presented for estimation of second order thermodynamic properties of electrolyte solutions. In order to provide a comprehensive understanding, the capability of modified electrolyte PC‐SAFT up to high pressure and temperature has been studied. In addition to the first order derivative thermodynamic properties, the Gibbs free energy, enthalpy and heat capacity of aqueous electrolyte solutions at infinite dilution are predicted. Using new methodology, the dielectric constant is modified to keep the pressure, temperature, and ionic strength dependency. Our results show that the Born term has a significant contribution on prediction of second order derivative properties. Meanwhile the impact of temperature‐dependent solution dielectric constant on standard state heat capacity is studied. Finally, the isobaric heat capacity at various salt concentrations is predicted without any adjustable parameters. The results of this work indicate an acceptable agreement with experimental data especially at high pressure and temperature. © 2017 American Institute of Chemical Engineers AIChE J, 2017     

Thermodynamics of supersaturated solutions: From ternary electrolyte+solute+H2O to binary solute+H2O systems

In our previous paper, a new experimental technique based on the potentiometric method was developed to obtain thermodynamic activity data (in form of activity ratio) particularly for ternary electrolyte+nonelectrolyte+H₂O solutions supersaturated with the nonelectrolyte. In this paper, a rigorous thermodynamic approach is proposed to derive activity data for binary nonelectrolyte+H₂O solutions in the supersaturated region, via cell potentials of an electrolyte tracer and solubility data of the nonelectrolyte. An analysis of thermodynamic consistency is presented to evaluate the reliability and accuracy of the measured data. A systematic experimental investigation of three ternary electrolyte+nonelectrolyte+H₂O and two binary nonelectrolyte+H₂O systems is reported in both under-saturated and supersaturated regions (up to a supersaturation level of approximately 27%). Interesting thermodynamic behaviors are observed and their significance is discussed, with the role of thermodynamics in exploration of crystallization phenomena highlighted.     

Empirical equations for the thermodynamic properties of aqueous sodium chloride

Equations for the thermodynamic properties of aqueous sodium chloride near its vapour pressure are presented. The equations are functions of temperature and concentration, and may be used to estimate aqueous sodium chloride's solubility, density, vapour pressure, specific enthalpy and entropy. They are valid for temperatures from 0 to 300°C, and concentrations extending to saturation with suitable accuracy. The thermodynamic equations are represented graphically and compared with published experimental data. These equations should prove to be a useful tool for modeling desalination equipment, particularly distillation processes.     

水盐体系汽液平衡的热力学模型研究

水盐体系的相平衡性质是化工单元操作的基础,在化学化工、海洋、地质等领域有着重要的研究价值。国内外许多学者对水盐体系汽液平衡进行了实验和理论的研究,构筑了各具特色的经验和半经验的模型。针对水盐体系,在NRTL理论的基础上,基于水化作用和混合盐假设建立了能够预测混合体系汽液平衡的活度系数扩展模型。通过对21组二元水盐体系和14组混合体系的关联计算,验证了该模型的可行性;同时,该模型可以采用二元体系参数直接预测计算混合水盐体系汽液平衡。     

Hydrodynamic properties of aqueous dextran solutions

The hydrodynamic performance of aqueous dextran solutions, including the rheological and thixotropic properties, were investigated. Three kinds of dextrans with different molecular weights were employed to examine the effects of the molecular weight, concentration, temperature, and so forth on the hydrodynamic properties of aqueous dextran solutions. The results showed that an aqueous solution of a dextran with a high molecular weight of 5.223 × 10⁵ at a high concentration of 30 wt % had pseudoplastic properties, in contrast to the conclusions of other researchers finding that aqueous dextran solutions were Newtonian liquids. The viscosity of the aqueous dextran solutions decreased with temperature, and the activation energy was calculated to be 16,849.2 J/mol with a 10 wt % dextran (weight‐average molecular weight = 5.223 × 10⁵) solution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009