Li+,K+/Cl-,CO32--H2O四元交互体系(298K)介稳相平衡的实验研究

我国西藏的扎布耶盐湖卤水以富含硼、锂、钾而闻名于世[1-2]。依据扎布耶盐湖卤水体系的主要成分,该卤水体系可简化Li K Na B4O72- CO32- Cl- SO42- H2O体系。针对西藏盐湖地处干旱、强日照特点,开展对扎布耶盐湖卤水体系的多温稳定及介稳相平衡研究,对于解释盐湖的演化及指     

Solid–liquid metastable equilibria in the quaternary system (NaCl–KCl–CaCl2–H2O) at 288.15 K

The solubilities and the physicochemical properties (densities, viscosities, refractive indices, conductivities, and pH) in the liquid–solid metastable system (NaCl–KCl–CaCl₂–H₂O) at 288.15 K have been studied using the isothermal evaporation method. Based on the experimental data, the dry-salt phase diagram, water-phase diagram and the diagram of physicochemical properties vs. composition in the system were plotted. The dry-salt phase diagram of the system includes one three-salt co-saturated point, three metastable solubility isotherm curves, and three crystallization regions corresponding to sodium chloride, potassium chloride and calcium chloride hexahydrate. Neither solid solution nor double salts were found. Based on the extended Harvie–Weare (HW) model and its temperature-dependent equation, the values of the Pitzer parameters β⁽⁰⁾, β⁽¹⁾, C for NaCl, KCl and CaCl₂, the mixed ion-interaction parameters θ_Na,K, θ_Na,Ca, θ_K,Ca, Ψ_Na,K,Cl, Ψ_Na,Ca,Cl, Ψ_K,Ca,Cl, the Debye–Hückel parameter A and the standard chemical potentials of the minerals in the quaternary system at 288.15 K were obtained. In addition, the average equilibrium constants of metastable equilibrium solids at the same temperature were obtained using a method derived from the activity product constant for the metastable system. Using the standard chemical potentials of the minerals and the average equilibrium constants of solids at equilibrium, the solubility predictions for the quaternary system are presented. A comparison between the calculated and experimental results shows that the predicted solubilities obtained with the extended HW model using the average equilibrium constants agree well with experimental data.     

Phases in the system Tb<Subscript>2</Subscript>O<Subscript>3</Subscript>-SeO<Subscript>2</Subscript>-H<Subscript>2</Subscript>O at 100°C and their physicochemical study

Summary The solubility isotherm of the system Tb₂O₃-SeO₂-H₂O at 100° was studied. The compounds of the three-component system were identified by the Schreinemakers’ method as well as by chemical and X-ray phase analyses. Simultaneous TG and DTA analyses of all compounds of the system were made. The mechanism of thermal decomposition was described.     

Phase equilibria in the CdI<Subscript>2</Subscript>-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript> system

The phase diagram of the system CdI₂-Bi₂O₃ is studied by means of X-ray diffraction, differential thermal analysis and measurements of the density of the material. As a result of the synthetic and peritectic interactions, two incongruently melting intermediate phases i.e. phase A — CdI₂·2Bi₂O₃ and phase B — CdI₂·4Bi₂O₃ (stable in the temperature interval 370–850°C) are formed.The phase A exists in two polymorphic forms with a temperature of the phase transition T =320–370°C. The unit cell parameters at low temperature modification of -CdI₂°2Bi₂O₃ were determined. (a=1.032 nm, b=1.046 nm, c=1.046 nm, =115.02°, =109.11° and =82.04°). The phases A and B have fields of homogeneity.The authors acknowledge thankfully the financial support for this work from the Ministry of Education and Science (Fond Scientific investigations — contract TN-1102).     

Study of the crystallization fields of cobalt(II) slenites in the system CoSeO<Subscript>3</Subscript>-SeO<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

Summary The solubility of CoSeO₃-SeO₂-H₂O system in the temperature region 298-573 K was studied. The phase diagram of cobalt(II)selenites was drawn and the crystallization fields for the different phases were determined. Depending on the conditions for hydrothermal synthesis, CoSeO₃×2H₂O, α-CoSeO₃×1/3H₂O, β-CoSeO₃×1/3H₂O, CoSeO₃, Co(HSeO₃)₂×2H₂O and CoSe₂O₅ were obtained. The different phases were proved and characterized by chemical and X-ray analyses, as well as IR spectroscopy.     

K2B4O7-Na2B4O7-Li2B4O7-H2O 四元体系15℃介稳相平衡研究

采用等温蒸发平衡法研究了四元体系K2B4O7-Na2B4O7-Li2B4O7-H2O15℃时的介稳相平衡及平衡液相的物化性质(密度,粘度,电导率,折光率,pH)。根据实验数据绘制了相图,相图中有一个共饱点E,三条单变度曲线E3F,E2F,E1F;三个平衡固相分别为：K2B4O7•4H2O,Na2B4O7•10H2O和Li2B2O4•16H2O;硼酸钾具有最大溶解度,硼酸钠具有最小溶解度。同时,根据试验数据绘制了组成－物化性质关系图,从图可见溶液的密度,粘度和折光率均随着溶液浓度的增大而逐渐增大,在共饱和点F处达到最大值,而溶液的pH值和电导率却随着溶液浓度的增大呈总体下降的趋势。     

Development of Accurate Chemical Equilibrium Models for Oxalate Species to High Ionic Strength in the System: Na—Ba—Ca—Mn—Sr—Cl—NO<Subscript>3</Subscript>—PO<Subscript>4</Subscript>—SO<Subscript>4</Subscript>—H<Subscript>2</Subscript>O at 25 °C

The development of an accurate aqueous thermodynamic model is described for oxalate species in the Na—Ba—Ca—Mn—Sr—Cl—NO₃—PO₄—SO₄—H₂O system at 25 °C. The model is valid to high ionic strength (as high as 10 mol·kg⁻¹) and from very acid (10 mol·kg⁻¹ H₂SO₄) to neutral and basic conditions. The model is based upon the equations of Pitzer and co-workers. The necessary ion-interaction parameters are determined by comparison with experimental data taken from the literature or determined in this study. The proposed aqueous activity and solubility model is valid for a range of applications from interpretation of studies on mineral dissolution at circumneutral pH to the dissolution of high-level waste tank sludges under acidic conditions.     

Phase equilibrium in the system RbCl-EuCl<Subscript>3</Subscript>-HCl(13.44, 22.75%)-H<Subscript>2</Subscript>O at 298.15 K

Solubility of the quaternary system RbCl-EuCl₃-HCl(13.44, 22.75%)-H₂O at 298.15 K was determined and corresponding equilibrium diagrams were constructed. The quaternary system is simple, and consists of two equilibrium solid phases RbCl and EuCl₃ · 6H₂O. The composition of double saturation point (average) is 13.29% HCl, 16.18% RbCl, and 18.72% EuCl₃ for the RbCl-EuCl₃-HCl(13.44%)-H₂O quaternary system, and 22.44% HCl, 15.59% RbCl, and 6.26% EuCl₃ for the RbCl-EuCl₃-HCl (22.75%)-H₂O quaternary system.     

Li+，Na+//CO32-，B4O72--H2O交互四元体系273 K介稳相平衡研究

我国青藏高原由于特殊的地理气候特点而盐湖众多,西藏境内的扎布耶盐湖卤水中锂、硼、钾浓度之高,在世界盐湖中也非常罕见[1-3].     

Structural and thermal studies on the solid products in the system MnSeO<Subscript>3</Subscript>-SeO<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

The solubility of MnSeO₃-SeO₂-H₂O system was studied in the temperature region 25–300°C. The compounds of the three-component system were identified by the Schreinemaker’s method. The phase diagram of manganese(II) selenites was drawn and the crystallization fields for the different phases were determined. Depending on the conditions for hydrothermal synthesis, MnSeO₃·H₂O, MnSeO₃·3/4H₂O, MnSeO₃·l/3H₂O and MnSe₂O₅ were obtained. The different phases were proven and characterized by chemical, powder X-ray diffraction and thermal analyses, as well as IR spectroscopy. The kinetics of dehydration and decomposition of MnSeO₃·H₂O was studied under non-isothermal heating. Based on 4 calculation procedures and 27 kinetic equations, the values of activation energy and pre-exponential factor in Arrhenius equation were calculated for both processes.     

Ternary water-salt system Sm(CCl<Subscript>3</Subscript>COO)<Subscript>3</Subscript>-Er(CCl<Subscript>3</Subscript>COO)<Subscript>v</Subscript>-H<Subscript>2</Subscript>O at 298 K

The system of samarium and erbium trifluoroacetates and water has been studied by the isothermal solubility technique at 298 K. The composition of the solids has been determined using the Schreinemakers wet residue technique. The refractive indices, specific volumes, and viscosities of liquid phases and the refractive indices of solid residues have been determined. A continuous solid solution is found to form in the system. Some thermodynamic parameters have been determined for this solid solution.     

Solid solutions in the system Nd(CCl<Subscript>3</Subscript> COO)<Subscript>3</Subscript>-Y(CCl<Subscript>3</Subscript> COO)<Subscript>3</Subscript>-H<Subscript>2</Subscript> O at 298 K

The water-salt system consisting of neodymium and yttrium trichloroacetates is studied by the isothermal solubility method at 298 K. The compositions of solid phases are determined by the Schreinemakers wet residues technique. Refractive indices, specific volumes, and viscosities for liquid phases and refractive indices of crystals for solid phases are determined. Continuous solid solutions are found in the system; some their thermodynamic characteristics are calculated.     

Specific features of the thermodynamics of activation in the LaNi<Subscript>5</Subscript>-H<Subscript>2</Subscript> and CeNi<Subscript>5</Subscript>-H<Subscript>2</Subscript> systems

Using heat conducting Tian—Calvet calorimetry and volumetric measurements, the first hydrogen absorption—desorption cycles in the LaNi₅-H₂ and CeNi₅-H₂ systems were studied. The pressure—composition isotherms were plotted, the equilibrium pressures of hydrogen along the absorption and desorption branches and in the region of hysteresis for different activation steps were determined, and the enthalpies of phase transitions α → β and β → α were calculated. The profiles of the heat evolution curves were analyzed. It was concluded that the mechanism of the reactions studied changes upon activation.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 134–139, January, 2005.     

Interactions in the system Mn(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-HCONH<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

Solubilities and solid phases in the system Mn(NO₃)₂-HCONH₂-H₂O were studied by an isothermal method at 25°C. The congruently saturating compound Mn(NO₃)₂ · 2HCONH₂ · 2H₂O was isolated; the concentration conditions for its crystallization in the system were determined. The solid phases of the system were characterized by physicochemical methods (X-ray powder diffraction, differential thermal analysis, IR spectroscopy, and crystal-optical analysis).     

Computational investigation into the phase transitions from AlPO<Subscript>4</Subscript>-H<Subscript>3</Subscript>

Open-framework aluminophosphates constitute an important family of materials due to their enormous potential applications in catalysis, exchange and gas separation, such as aluminosilicate zeolites. These compounds, whose formations are promoted by the presence of organic templates, are constructed from alternation of AlO4 and PO4 tetrahedral with an Al/P ratio of unity. However, there are quite a number of AlPOs that contain 5- or 6-coordinated Al atoms which are coordinated to extra-fram…     

Phase equilibria in the Ce<Subscript>2</Subscript>O<Subscript>3</Subscript>-K<Subscript>2</Subscript>O-P<Subscript>2</Subscript>O<Subscript>5</Subscript> system

Ce₂O₃-K₂O-P₂O₅ ternary system has been investigated by thermoanalytical methods (DTA, DSC), powder X-ray diffraction, XPS and IR spectroscopy. The existence of three double potassium-cerium(III) phosphates has been confirmed and a new binary phosphate K₄Ce₂P₄O₁₅ has been found. Phase diagram and isothermal section at room temperature of the system Ce₂O₃-K₂O-P₂O₅ have been presented.     

Kinetics of the oxidation of diethyl sulfide in the B(OH)<Subscript>3</Subscript>-H<Subscript>2</Subscript>O<Subscript>2</Subscript>/H<Subscript>2</Subscript>O system

Data obtained for the kinetics of oxidation of diethyl sulfide (Et₂S) by hydrogen peroxide in aqueous solution catalyzed by boric acid indicate that monoperoxoborates B(O₂H)(OH) ₃ ⁻ and diperoxoborates B(O₂H)₂(OH) ₂ ⁻ are the active species. The rates of the reactions of Et₂S with B(O₂H)(OH) ₃ ⁻ and B(O₂H)₂(OH) ₂ ⁻ are 2.5 and 100 times greater than with H₂O₂. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 1, pp. 38–42, January–February, 2007.     

Preparation and physicochemical study of nickel(II) thiostannate in the NiCl<Subscript>2</Subscript>-SnS<Subscript>2</Subscript>-H<Subscript>2</Subscript>O system

Nickel(II) thiostannate is prepared in the NiCl₂-SnS₂-H₂O system by precipitation from solutions. Its formation temperature and homogenization time are determined. The synthesis of NiSnS3 from the ammonium acetate buffer solution is found to last 6–8 h at 80–90°C. The elemental composition of ternary nickel(II) thiostannate is detrermined by chemical analysis.     

(Solid+Liquid) Equilibria in the Quaternary System Na2B4O7-MgB4O7-K2B4O7-H2O at 288 K

(Solid+Liquid) phase equilibria in the quaternary system Na₂B₄O₇‐MgB₄O₇‐K₂B₄O₇‐H₂O at 288 K were studied experimentally using the method of isothermal solution saturation. Solubility of any single salt in the solution of the quaternary system was determined experimentally. Based on the experimental data achieved, the phase diagram and water content diagram of the quaternary system were constructed, respectively. In the phase equilibrium diagram of the quaternary system Na₂B₄O₇‐MgB₄O₇‐K₂B₄O₇‐H₂O at 288 K, there are one invariant point E, three univariant curves E1E, E2E and E3E, and three fields of crystallization corresponding to Na₂B₄O₇·10H₂O, K₂B₄O₇·4H₂O and MgB₄O₇·9H₂O. The experimental results show that potassium borate (K₂B₄O₇·4H₂O) have higher solubilities than the magnesium borate and sodium borate in the quaternary system Na₂B₄O₇‐MgB₄O₇‐K₂B₄O₇‐H₂O at 288 K.     

Phase equilibria and heterogenization of supercritical fluids in the K<Subscript>2</Subscript>SO<Subscript>4</Subscript>-K<Subscript>2</Subscript>CO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system

This experimental study of phase equilibria in the K₂SO₄-K₂CO₃-H₂O system at 385–500°C and pressures up to 100 MPa is directed to determine the sequence of phase transformations that generate heterogeneous supercritical fluids from the homogeneous one; the homogeneous supercritical region spreads into the ternary system from the K₂SO₄-H₂O subsystem. We found that heterogenization of supercritical fluid upon addition of K₂CO₃ starts with l₁=l₂ critical phenomena in solid saturated solutions and is attended by amalgamation of the stable immiscibility region that spreads from the K₂CO₃-H₂O system with the metastable immiscibility region that originates from the K₂SO₄-H₂O system. Our experimental results and the topological analysis of phase equilibria at temperatures above the critical point of water gave us the full scenario of the phase behavior of the title ternary system in the regions of fluid equilibria, g=l and l₁=l₂ critical phenomena, and liquid-liquid phase separation in two-, three-, and four-phase equilibria.