Zirconium Dioxide Solubility in High Temperature Aqueous Solutions

The heat transport purification system of CANDU nuclear reactors is used to remove particulates and dissolved impurities from the heat transport coolant. Zirconium dioxide shows some potential as a high-temperature ion-exchange medium for cationic and anionic impurities found in the CANDU heat transport system (HTS). Zirconium in the reactor core can be neutron activated, and potentially can be dissolved and transported to out-of-core locations in the HTS. However, the solubility of zirconium dioxide in high-temperature aqueous solutions has rarely been reported. This paper reports the solubility of zirconium dioxide in 10⁻⁴ mol⋅kg⁻¹ LiOH solution, determined between 298 and 573 K, using a static autoclave. Over this temperature range, the measured solubility of zirconium dioxide is between 0.9 and 12×10⁻⁸ mol⋅kg⁻¹, with a minimum solubility around 523 K. This low solubility suggests that its use as a high-temperature ion-exchanger would not introduce significant concentrations of contaminants into the system. A thermodynamic analysis of the solubility data suggests that Zr(OH)₄⁰ likely is the dominant species over a wide pH region at elevated temperatures. The calculated Gibbs energies of formation of Zr(OH)₄⁰(aq) and Zr(OH)₄(am) at 298.15 K are −1472.6 kJ⋅mol⁻¹ and −1514.2 kJ⋅mol⁻¹, respectively. The enthalpy of formation of Zr(OH)₄⁰ has a value of −1695±11 kJ⋅mol⁻¹ at 298.15 K.     

Nickel(II) Oxide Solubility and Phase Stability in High Temperature Aqueous Solutions

A platinum-lined, flowing autoclave facility was used to investigate the solubility behavior of nickel(II) oxide (NiO) in deoxygenated ammonium and sodium hydroxide solutions, between 21 and 315°C. Solubilities were found to vary between 0.4 and 400 nmol-kg^–1. The measured nickel ion solubilities were interpreted via a Ni(II) ion hydroxo- and ammino-complexing model, and thermodynamic functions for these equilibria were obtained from a least-squares analysis of the data. Two solid phase transformations were observed: at temperatures below 149°C, the activity of Ni(II) ions in aqueous solution was controlled by a hydrous Ni(II) oxide (theophrastite) solid phase rather than by anhydrous NiO (bunsenite); above 247°C, Ni(II) activities were controlled by cubic rather than by rhombohedral bunsenite.     

Dielectric Shielding of Ionic Charges in Aqueous Solutions of Different Ionic Strength

The thermodynamic functions of the proton transfer H₂tn²⁺+tn → 2 Htn⁺ (tn = 1,3-diaminopropane) have been determined in aqueous solutions containing different amounts of KCl (0.05 ? μ ? 3.01). The free energy (?ΔG) of the process decreases, whereas the enthalpy (-ΔH) increases with μ. There is reason to believe that the reaction is entirely controlled by the Coulomb forces between the two protonic charges. The electrostatic energy involved can be described in terms of a model incorporating an effective dielectric constant εe, such that δε_e/δμ and δ²ε_e/δμδT are both positive. The polarisation of pure water is produced by orientation of hydrogen-bonded dipole molecules H₂O, whereas the electrolyte solution is polarised in addition by dislocation of the ions K⁺ and Cl^?. Our results demonstrate that the former type of polarisation is much more temperature dependent than the latter.     

Solubility and Hydrolysis of La, Pr, Eu, Er, and Lu in 1 M NaCl Ionic Strength at 303 K

The pLn-pC _H diagrams obtained by a radiometric technique were used for the determination of the solubility and the first hydrolysis constants for La, Pr, Eu, Er, and Lu in 1 M NaCl ionic strength at 303 K. The saturation and unsaturation zones, and the borderline of precipitation were determined from these diagrams. The first hydrolysis constants were determined from pH titrations where no precipitation was found; these data were treated with the SUPERQUAD program. Fitting methods involving pLn versus pC _H and the average ligand number vs. pC _H were used to calculate both the first hydrolysis constants and the solubility products. The log K _sp values obtained for La, Pr, Eu, Er, and Lu were –19.53, –20.92, –22.24, –22.62, and –23.05 and the log* ₁ average values obtained were –8.87 ± 0.05, –8.54 ± 0.04, –8.34 ± 0.03, –8.16 ± 0.04, and –8.11 ± 0.03, respectively, under CO₂ free conditions. Finally, the results were compared with those found in the literature.     

水的内压与水溶液的Henry常数

为使前文提出的气体溶解度的新模型能够适用于稀水溶液,由分子间作用位能 函数建立了一个水的内压方程,它能用来描述宽阔温度范围内水的内压随密度的改 变。用38种气体在水中的Henry常数实验数据对新模型检验结果表明,计算值与实 验值间的一致性是令人满意的。此外,新模型还能由溶质与溶剂和溶剂与溶剂分子 间的作用很好地解释Henry常数的大小及其随温度的变化规律。     

Ionic Solvation in Aqueous and Nonaqueous Solutions

 The history of studies on ionic solvation is briefly reviewed, and structural and dynamic properties of solvated ions in aqueous and nonaqueous solutions are discussed. An emphasis is placed on ionic solvation in nonaqueous mixed solvents in which preferential solvation of ions takes place. A new parameter for expressing the degree of preferential solvation of an ion is proposed.     

木糖醇在纯水和碱金属卤化物水溶液中的稀释焓

应用等温流动微量热法测定了298.15 K时木糖醇在纯水和碱金属卤化物水溶液中的稀释焓, 根据McMillan- Mayer理论计算了木糖醇在溶液中的二到四阶焓相互作用系数. 结果表明, 木糖醇在碱金属卤盐溶液中的焓对相互作用系数h₂均为正值, h₂值随着碱金属阳离子或卤素阴离子半径的增大皆依次增大. 根据木糖醇参与的溶质-溶质, 溶质-溶剂等弱相互作用, 对该种多元醇在碱金属卤盐水溶液中的焓相互作用系数的变化进行了解释.     

Ionic Solvation in Aqueous and Nonaqueous Solutions

Summary.  The history of studies on ionic solvation is briefly reviewed, and structural and dynamic properties of solvated ions in aqueous and nonaqueous solutions are discussed. An emphasis is placed on ionic solvation in nonaqueous mixed solvents in which preferential solvation of ions takes place. A new parameter for expressing the degree of preferential solvation of an ion is proposed. Received January 16, 2001. Accepted January 31, 2001     

Solubility of Fumaric Acid in Aqueous Alcohol Solutions

The solubility of fumaric acid in aqueous alcohol solutions was experimentally measured over the temperature range of (278.15–333.15) K by employing an analytical stirred-flask method. The experimental data showed that the solubility of fumaric acid in the binary mixtures increases with increases of both temperature and mass fraction of the organic solvents. The experimental data were well correlated with the modified Apelblat equation and the Buchowski–Ksiazaczak λh equation. In addition, the calculated solubilities showed good agreement with the experimental results. It was found that the modified Apelblat equation gave better correlation results than the Buchowski–Ksiazaczak λh equation. The experimental results should be useful for optimizing the process of purification of fumaric acid in industry.     

肌醇在纯水和卤化钠水溶液中稀释过程的热力学性质

应用微量热法测定了298.15 K时肌醇在纯水和卤化钠水溶液中的稀释焓, 根据McMillan-Mayer理论, 计算了肌醇在溶液中的二到四阶焓相互作用系数. 结果表明, 肌醇在卤化钠溶液中的焓对相互作用系数h2均为负值, 并且随着卤素阴离子半径的增大, h2的绝对值呈增大趋势.     

D-甘露醇与D-山梨醇在纯水和卤化钠水溶液中的稀释焓

应用等温流动微量热技术测定了298.15 K下D-甘露醇和D-山梨醇在纯水和卤化钠水溶液中的稀释焓,利用M cM illan理论计算了D-甘露醇和D-山梨醇在纯水和卤化钠水溶液中焓相互作用系数.结果表明,D-甘露醇和D-山梨醇在纯水和卤化钠水溶液中的二阶焓相互作用系数均为正值,并随着卤离子半径的变化而相应变化;且同种溶剂中,D-甘露醇的二阶焓相互作用系数要大于D-山梨醇的.结合两分子结构的差异,通过溶质-溶质相互作用和溶剂-溶质相互作用对这一结果进行了讨论.     

NaCl、KCl在蔗糖水溶液中的粘度

报导了在298．15及308．15K下，NaCl、KCl在含有蔗糖5，10，15，20，25％（质量分数w）的水溶液中的密度及粘度数据．计算了在无限稀释条件下，NaCl和KCl在该体系中的粘度B系数及偏摩尔体积．结果发现：两种电解质的B系数随蔗糖含量的增加及温度的升高而增大且对蔗糖水溶液的结构起破坏作用．讨论了该三元体系内部溶质－溶质、溶质－溶剂间的相互作用，同时应用流动过渡状态理论计算了两种电解质在各组成下蔗糖水溶液中的流动活化参数     

Solubility and Thermodynamic Properties of Ammonium-Based Gemini Ionic Liquids in Pure Solvents

Journal of Solution Chemistry - Asymmetrical ammonium-based gemini ionic liquids, 1-trimethylammonium-3-(1-methylpiperidinium)propane dibis[(trifluoromethyl)sulfonyl]imide ([N111C3MPip][NTf2]2) and...     

Solubility Calculations of Methane and Ethane in Aqueous Electrolyte Solutions

Journal of Solution Chemistry - Accurate calculation of light hydrocarbon solubilities in aqueous electrolyte solutions is critical for petroleum and geochemical applications. However, very few...     

Solubility of Rhodochrosite (MnCO3) in NaCl Solutions

The solubility of rhodochrosite (MnCO₃) at 25°C under constant carbon dioxide partial pressure p(CO₂) was determined in NaCl solutions as a function of ionic strength I. The dissolution of MnCO₃(s) for the reaction

Solubility of Siderite (FeCO3) in NaCl Solutions

The solubility of siderite (FeCO₃) at 25°C under constant CO₂ partial pressure [p(CO₂)] was determined in NaCl solutions as a function of ionic strength. The dissolution of FeCO₃(s) for the reaction