用微扰理论状态方程预测电解质水溶液的密度

对微扰理论的电解质水溶液状态方程作了进一步简化．由水的分子参数和离子直径,计算了包含强酸在内的12个单一电解质水溶液、9个二元和1个四元电解质水溶液在不同温度下的密度．对单一电解质水溶液密度关联准确度在1％之内,对混合电解质水溶液密度预测的平均相对偏差在2％左右,若阳离子直径采用由单一电解质水溶液的回归值代替Pauling直径,则能进一步改善预测准确度．     

高温高压下氯化钠水溶液的热力学(Ⅱ)——在823K及100MPa条件下NaCI-H_2O体系的热力学性质

本文将(I)报中提出的简易方程式推广应用到823K和100MPa的NaCl水溶液,NaCl的最高浓度达65.2wt%(三相点时的饱和溶解度)下热力学性质的计算.这些热力学性质包括溶液中水的活度、氯化钠的平均离子活度系数、溶液的Gibbs自由能,计算值与实验值吻合较好.文中列出了不同温度压力下的w和△_8G_2~0/RT值及其变化曲线、和本文提出的参考压力值P_r,为高温高压下电解质水溶液的研究作了初步的探索.     

硫酸水溶液的水蒸汽压、活度和(火用)值的计算

本文探讨了有关硫酸水溶液水蒸汽压、活度和(火用)值的工程计算方法。为了能在全浓度范围(硫酸重量分率浓度,C=0～1.0)关联文献上的水蒸汽压数据,本文提出了计算硫酸溶液上水蒸汽压的经验方程式: P=P_oe~(-C×e~(A+B×C)) 并由此推出计算硫酸水溶液中水的活度系数的半经验式: a_水=e_~(-C×e~(A+B×C)) 同时,根据Gibbs—Duhem方程,计算出硫酸溶液中硫酸的活度以及溶液的化学册、过剩(火用)等数据。     

一种预测电解质溶液密度的新方法

根据对应状态原理的基本思想本文提出了一种预测电解质溶液密度的新方法。以CaCl2 溶液作为参考流体 ,本文得到了溶液渗透压和溶剂水的表观摩尔体积的定量关系。假定该关系对所有电解质水溶液都是适用的 ,则由离子半径和溶液组成 ,就可以计算单一电解质溶液和预测混合电解质溶液在全浓度和 2 73K～ 373K范围内的密度。模型的可靠性通过 30个二元电解质溶液在 2 98 1 5K和 1 1个单一电解质溶液在 2 73K～ 373 1 5K范围内密度的预测进行了检验。采用与温度和浓度无关的离子半径的优化值 ,本文对密度预测的总平均相对偏差小于 1 %。该方法公式简单 ,计算精度可以满足工业设计计算的要求     

二元无机水溶液的(火用)值计算法

本文探讨了有关二元无机水溶液的蒸汽压、溶质与溶剂的偏摩尔(?),溶液总(?)值的工程计算方法。提出了能关联全浓度范围内溶液蒸汽压数据的经验式和计算无机水溶液中水的偏摩尔(?)的半经验式。根据Gibbs-Duhem方程,推导出计算二元无机水溶液(?)值的通用式。     

硫酸加工天然硼砂矿生产硼酸的相平衡

以Pitzer电解质溶液理论为基础 ,引入离子强度函数来表达高温 (1 0 0℃ )时两电解质之间及电解质与非电解质之间的作用系数 ,计算了 2 5℃和 1 0 0℃时H3BO3-Na2 SO4-NaCl-H2 O四元体系的溶解度 ,计算值与实验测定值相吻合 .应用该四元体系的相图讨论了用西藏天然硼砂生产硼酸的工艺过程 .     

强电解质标准生成热的计算

本文介绍用离子贡献法计算水溶液中强电解质标准生成热和固体电解质的标准生成热,以及水溶液中离子标准生成热的计算。为了读者使用本法计算强电解质标准生成热的方便,文中还列出了部分离子的标准生成热和部分电解质的溶解热,供读者参考。     

计算电解质水溶液导热系数新方法

根据电解质水溶液导热系数的变化规律 ,发展了一种计算不同温度下电解质水溶液导热系数的普适方法 ,该方法不仅适用于稀溶液 ,而且适用于浓溶液 ,同时适用于高浓度的强酸和强碱溶液。对 5 1种电解质 35 5个数据点的计算结果表明 ,导热系数计算值与文献推荐值的一致性令人满意 ,平均误差 3.87% ,计算精度优于文献方法     

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。     

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。     

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.     

Temperature dependence of interaction parameters in electrolyte NRTL model

The electrolyte NRTL model captures the electrolyte solution nonideality over the entire concentration range with two binary interaction parameters. Here, the temperature dependence of the binary parameters is formulated with a Gibbs‐Helmholtz expression containing three temperature coefficients associated with Gibbs energy, enthalpy, and heat capacity contributions. We show the Gibbs energy term is correlated to the excess Gibbs energy of aqueous single electrolyte systems at 298.15 K. With the Gibbs energy term identified, the enthalpy term is correlated to the excess enthalpy at 298.15 K. With the Gibbs energy term and the enthalpy term identified, the heat capacity term is correlated to the excess heat capacity at 298.15 K. Once the temperature coefficients are properly quantified by regressing data of mean ionic activity coefficient, excess enthalpy, and heat capacity at 298.15 K or the equivalents, the model provides a comprehensive thermodynamic framework to represent all thermodynamic properties of electrolyte solutions. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1244–1253, 2016     

用微扰理论状态方程计算电解质水溶液的活度系数

近年来,电解质溶液理论的研究日益活跃^[1]。因为理论模型能反映微观粒子参数与溶液结构和性质间的关系,参数物理意义明确,预测功能强。电解质溶液的原始模型中,忽略了离子－溶剂和溶剂－溶剂相互作用,而只考虑在溶剂平均场中离子之间的相互作用。这类模型不能反映溶液的本质和溶质－溶剂间的真实相互作用,因此很难推广到混合溶剂电解质溶液。用微扰理论研究电解质溶液的状态方程已经取得很大进展^[2]。硬球离子流体^[3]和离子－偶极^[4]模型流体的微扰理论处理结果已经成功地用于构筑实际电解质溶液的状态方程^[5]。作者采用微扰理论研究了电解质溶液的密度性质^[6],本文将进一步研究活度系数的计算问题。     

基于微扰理论和平均球近似的强电解质水溶液分子热力学模型

用平均球近似处理离子-离子间的静电相互作用,用微扰理论处理电解质溶液中各种粒子间的其他相互作用,建立了一个强电解质水溶液的分子热力学模型。该模型将阳离子直径作为唯一的可调参数,对52种1-1、1-2、2-1、2-2型强电解质水溶液离子的平均活度系数进行了关联,与现有模型比较,该模型形式相对简单,具有很好的适用性和满意的计算精度。     

Effect of Ionic Strength on the Stability of Binary Ceramic Suspensions

The colloidal stability of aqueous Al₂O₃/ZrO₂ and Al₂O₃/SiC suspensions in the presence of electrolyte was investigated by rheological measurement. It was observed that the stability of binary systems improved with increasing ionic strength, where the solution pH value was maintained in the middle range of the two isoelectric points of the constituent powders. In this case, the electrostatic attractive interaction between dissimilar particles became more prominent when their number ratio approached unity. In addition, the salt-dependent stability was studied over the entire range of pH and relative component fraction. The results showed that the role of ionic strength in promoting flocculation or stabilization of colloidal dispersions was mainly determined by the predominant electrostatic interaction between particles, and the experimental stability maps were used to distinguish the stable and unstable suspensions with the addition of an electrolyte.     

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.     

GENERAL LINEARIZED MATRIX THEORY OF ELECTROCHEMICAL MASS TRANSFER WITH APPLICATIONS TO ELECTRODE PROCESSES AND ION EXCHANGE

A general linearized matrix theory for electrochemical mass transfer is presented. The accuracy of the theory when applied to cases where electric current exists is tested by comparing results with exact calculations of the effect of ionic migration on limiting currents at a rotating disk electrode with laminar flow and at a flat plate electrode adjacent to a stagnant fluid film. Application of the theory is further illustrated by using it to calculate the effect of ionic migration on limiting currents in a turbulent, law-of-the-wall boundary layer. Finally, the theory is used to evaluate commonly used “film-model” methods for generalizing binary mass-transfer correlations to multicomponent nonideal mixtures. For this last purpose, a film-model generalization method was developed for nonideal electrolyte mixtures. The method is equivalent to that used by Krishnamurthy and Taylor (1985) for mass-transfer in nonideal nonelectrolyte mixtures. Results using the film-model method are compared to matrix calculations of multicomponent ion-exchange mass transfer across a laminar boundary layer and in fixed and fluidized beds.