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1.
采用等温蒸发法研究了五元体系Li, K//, , -H2O 在288 K时的介稳相平衡关系, 测定了该五元体系在288 K条件下的介稳平衡的溶解度和溶液密度, 根据实验数据绘制了相应的介稳平衡相图和水图. 相平衡研究结果表明该五元体系介稳相平衡中有复盐K2SO4•Li2SO4生成, 其介稳相图(Li2CO3饱和)有4个共饱和点, 9条单变量曲线, 6个Li2CO3饱和的结晶区分别为LiBO2•8H2O, K2B4O7•4H2O, K2CO3•3/2H2O, K2SO4, Li2SO4•H2O和复盐 K2SO4•Li2SO4.  相似文献   

2.
Experimental studies on the metastable solubilities and physicochemical properties (density and refractive index) in the ternary systems K2SO4 + K2B4O7 + H2O and KCl + K2B4O7 + H2O at 308.15 K were determined with the method of isothermal evaporation. According to the experimental results, the phase diagrams of the two ternary systems were plotted. In the phase diagrams, there are both two isotherm evaporation curves, one eutectic point corresponding to K2SO4 + K2B4O7 · 4H2O, and KCl + K2B4O7 · 4H2O, respectively. Both of the ternary systems belong to a simple eutectic type, and neither double salts nor solid solutions formed in the ternary systems. A comparison of the stable and metastable phase diagrams of the ternary systems K2SO4 + K2B4O7 + H2O and KCl + K2B4O7 + H2O shows that the supersaturated phenomenon of potassium borate tetrahydrate is significant and easier to appear the metastable behavior.  相似文献   

3.
Metastable equilibrium solubilities and properties such as densities, conductivity, pH, refractive index, and viscosity of the solution were determined experimentally. According to the experimental data, the metastable equilibrium phase diagram was plotted. In the phase diagram, there are three invariant points, seven univariant curves, five fields of crystallization: Li2SO4 · H2O, K2SO4, Li2B4O7 · 3H2O, K2B4O7 · 4H2O, and K2SO4 · Li2SO4. The double salt K2SO4 · Li2SO4 was found in the quaternary system metastable equilibria. Lithium sulfate (Li2SO4) has the highest concentration and strong salting-out effects on other salts.Also, the relationship diagram between the properties and the ion concentration of solution was constructed. It can be seen from the relationship diagram that the equilibrium solution density values, viscosity values, and refractive index values are increased apparently with the rise of sulfate ion concentration, reaching the maximum values at eutonic point F3. Electrical conductivity values and pH values, however, fall down with the rise of ion concentration on the whole.  相似文献   

4.
The metastable solubilities and densities of the aqueous ternary system K2SO4+MgSO4+H2O at (288.15 and 308.15) K were determined with the isothermal evaporation method. Using the experimental results, the metastable phase diagram and the densities versus composition diagram were plotted. In the metastable phase diagrams of the ternary system at (288.15 and 308.15) K, there are in all two invariant points, three univariant solubility curves, and three metastable crystallization regions corresponding to arcanite (i.e., anhydrous potassium sulfate, K2SO4), picromerite (K2SO4⋅MgSO4⋅6H2O) and epsomite (MgSO4⋅7H2O) that are formed in the metastable equilibrium system. A comparison of the stable and metastable phase diagrams at each temperature shows that the metastable regions of magnesium sulfate are obvious, and the crystallizing regions of epsomite and arcanite are much larger than those in the stable phase diagram. The densities of the system changed regularly with the magnesium sulfate content. The resulting information can be used to recover potassium or remove magnesium. The calculated densities using an empirical equation agree well with the experimental results.  相似文献   

5.
桑世华  殷辉安  曾英  刘凤英 《化学学报》2006,64(22):2247-2253
采用等温蒸发法研究了四元体系Li, Na// SO42-, CO32--H2O 288 K介稳相平衡及平衡液相的密度、电导率、折光率、粘度和pH值, 测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质. 根据实验数据绘制了相应的介稳相图. 研究发现: 该体系介稳平衡中有复盐Na3Li(SO4)2•6H2O形成. 其介稳相图中有3个共饱点, 7条单变量曲线, 平衡固相为: Li2SO4•H2O, Na2SO4, Na3Li(SO4)2•6H2O, Li2CO3, Na2CO3•10H2O. 复盐Na3Li(SO4)2•6H2O和一水硫酸锂(Li2SO4•H2O)的结晶区较小, 而Li2CO3的结晶区最大; 该四元体系介稳平衡条件下未发现Na2SO4•10H2O的结晶区.  相似文献   

6.
The solubility and the density in the aqueous ternary system (Li2SO4 + MgSO4 + H2O) at T = 308.15 K were determined by the isothermal evaporation. Our experimental results permitted the construction of the phase diagram and the plot of density against composition. It was found that there is one eutectic point for (Li2SO4 · H2O + MgSO4 · 7H2O), two univariant curves, and two crystallization regions corresponding to lithium sulphate monohydrate (Li2SO4 · H2O) and epsomite (MgSO4 · 7H2O). The system belongs to a simple co-saturated type, and neither double salts nor solid solution was found. Based on the Pitzer ion-interaction model and its extended HW models of aqueous electrolyte solution, the solubility of the ternary system at T = 308.15 K has been calculated. The predicted solubility agrees well with the experimental values.  相似文献   

7.
The phase and physicochemical properties diagrams of Li+,K+(Rb+)//borate–H2O systems at 323 K were constructed using the experimentally measured solubilities, densities, and refractive indices. The Schreinemakers’ wet residue method and the X-ray diffraction were used for the determination of the compositions of solid phase. Results show that these two systems belong to the hydrate I type, with no solid solution or double salt formation. The borate phases formed in our experiments are RbB5O6(OH)4 · 2H2O, Li2B4O5(OH)4 · H2O, and K2B4O5(OH)4 · 2H2O. Comparison between the stable phase diagrams of the studied system at 288, 323, and 348 K show that in this temperature range, the crystallization form of salts do not changed. With the increase in temperature, the crystallization field of Li2B4O5(OH)4 · H2O salt at 348 K is obviously larger than that at 288 K. In the Li+,K+(Rb+)//borate–H2O systems, the densities and refractive indices of the solutions (at equilibrium) increase along with the mass fraction of K2B4O7 (Rb2B4O7), and reach the maximum values at invariant point E.  相似文献   

8.
Solubilities of ternary systems Li+,K+/SO2-4-H2O (1) and Li+,Mg2+/SO42--H2O (2) were investigated by isothermal method at 25°C. Physico-chemical properties of solutions, such as density, refractive index, viscosity, conductivity and pH, were determined. Phase diagram of the system (1) consists of three solubility branches and three crystallization fields corresponding to K2SO4, Li2SO4·H2O and LiKSO4. LiKSO4 is an incongruent compound, and its transition point is estimated graphically to be 45.5–46.0°C. No solid solution of LiKSO4 with Li2SO4·H2O was found in the system. The system (2) is a simple eutonic type. Pitzer model of electrolyte solution was used to check the obtained solubilities. Data comparison gives good agreement. Two equations were used to correlate density, refractive index of the solution with its composition. Differences between measured and calculated values are less than 0.6% for density, 0.15% for the latter.  相似文献   

9.
The solubilities and densities of the solutions in the ternary system LiCl–NaCl–H2O at 308 and 348 K were determined by the method of isothermal dissolution equilibrium. There are one invariant point, two univariant isotherm dissolution curves, and two crystallization regions corresponding to monohydrate (LiCl · H2O) and NaCl, respectively. This system at both temperatures belongs to hydrate type I, and neither double salt nor solid solution was found. A comparison of the phase diagram for the ternary system at 273–348 K shows that the area of crystallization region of LiCl · H2O is decreased with the increasing of temperature, while that of NaCl is increased obviously. The solution density of the ternary system at two temperatures changes regularly with the increasing of LiCl concentration.  相似文献   

10.
The solid‐liquid equilibria in the quinary system Na+, K+//Cl?, SO2?4, B4O2?7‐H2O at 298 K had been studied experimentally using the method of isothermal solution saturation. Solubilities and densities of the solution of the quinary system were measured experimentally. Based on the experimental data, the dry‐salt phase diagram and water content diagram of the quinary system were constructed, respectively. In the equilibrium diagram of the quinary system Na+, K+//Cl?, SO2?4, B4O2?7‐H2O at 298 K, there are five invariant points F1, F2, F3, F4 and F5; eleven univariant curves E1F1, E2F2, E3F3, E4F5, E5F2, E6F4, E7F5, F1F4, F2F4 F1F3 and F3F5, and seven fields of crystallization saturated with Na2B4O7 corresponding to Na2SO4, Na2SO4·10H2O, Na2SO4·3K2SO4 (Gla), K2SO4, K2B4O7·4H2O, NaCl and KCl. The experimental results show that Na2SO4·3K2SO4 (Gla), K2SO4 and K2B4O7·4H2O have bigger crystallization fields than other salts in the quinary system Na+, K+//Cl?, SO2?4, B4O2?7‐H2O at 298 K.  相似文献   

11.
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。  相似文献   

12.
An experimental study on metastable equilibria at T=288 K in the quinary system Li2CO3 + Na2CO3 + K2CO3 + Li2B4O7 + Na2B4O7 + K2B4O7 + H2O was done by isothermal evaporation method. Metastable equilibrium solubilities and densities of the solution were determined experimentally. According to the experimental data, the metastable equilibrium phase diagram under the condition saturated with Li2CO3 was plotted, in which there are four invariant points; nine univariant curves; six fields of crystallization: K2CO3 · 3/2H2O, K2B4O7 · 5H2O, Li2B2O4 · 16H2O, Na2B2O4 · 8H2O, Na2CO3 · 10H2O, NaKCO3 · 6H2O. Some differences were found between the stable phase diagram at T=298 K and the metastable one at T=288 K.  相似文献   

13.
The Pitzer ion-interaction model has been used for thermodynamics simulation of the ternary system Cs2SO4-MgSO4-H2O at 298.15 K. The Pitzer ternary mixing parameter $ \psi _{CsMgSO_4 } $ \psi _{CsMgSO_4 } and thermodynamic characteristics for double salt Cs2SO4 · MgSO4 · 6H2O have been calculated and the theoretical solubilities isotherm has been plotted.  相似文献   

14.
Non-isothermal studies of the dehydration of double salt hydrates of the type K2AB4·M(II)SO4·6H2O where AB4BeF2?4 or SeO2?4 and M(II)Mg(II), Co(II), Ni(II), Cu(II) or Zn(II) and their D2O analogues were carried out. Thermal parameters like activation energy, order of reaction, enthalpy change, etc., for each step of dehydration were evaluated from the analysis of TG, DTA and DTG curves. These parameters were compared with the corresponding double sulphate, i.e., K2SO4·M(II)SO4·6H2O and their D2O analogues. The role of divalent cation on the thermal properties of dehydration of the salt hydrates and also the effect on the thermal properties due to deuteration were discussed. The order of reaction was always found unity. The values of ΔH were within ~11-~19 kcal mol?1  相似文献   

15.
Saturating solid phases, Ce2(SO4)3·hH2O, with hydrate numbers h equal to 12, 9, 8, 5, 4 and 2, have been identified by critical evaluation of the solubility data in the system Ce2(SO4)3—H2O over the temperature range 273–373 K. The results are compared with the respective TG—DTA—DSC and X-ray data. The solubility smoothing equations, transition points and solution enthalpy estimators of the identified hydrates are given. The stable equilibrium solid phases are concluded to be only Ce2(SO4)3·9H2O at 273–310 K, Ce2(SO4)3·4H2O at 310–367 K and Ce2(SO4)3·2H2O at 367–373 K. Divergencies of up to 185% in the reported solubility data are mainly due to a variety of metastable equilibria involved in the close crystallization fields, and incorrect assignments of the saturating solid phases. Since a similar variety of the hydrate numbers exists for the analogous La(III) system, it most probably also occurs for the corresponding Pu(III), Np(III) and U(III) systems. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
Phase equilibria studies of the system K2SO4–MnSO4–H2O published revealed discrepancies between the data presented in the literature regarding the solid phases formed at ambient temperatures. The solubility in the system at 298 K and 313 K was determined. At 298 K, the existence of the double salt K2SO4·3MnSO4·5H2O and of MnSO4·H2O was confirmed. The examinations at 313 K showed the formation of the stable solid phases MnSO4·H2O, K2SO4·2MnSO4, K2SO4·MnSO4·1.5H2O, K2SO4 and the formation of a metastable phase K2SO4·MnSO4·2H2O.  相似文献   

17.
Phase equilibria of the Na,K,Mg,Ca||SO4,Cl–H2O system at 50°С in the polyhalite (K2SO4 · MgSO4 · 2CaSO4 · 2H2O) crystallization region were studied using the translation method. Polyhalite was found to be involved, as an equilibrium phase of the title system at 50°С, in 17 invariant points, 36 monovariant curves, and 24 divariant fields. A fragment of equilibrium phase diagram of the title system in the polyhalite crystallization region was constructed.  相似文献   

18.
The Pitzer ion-interaction model has been used for calculations of thermodynamic characteristics of double salts 3RbCl · LiCl · 2H2O and RbCl · 2LiCl · 4H2O in the ternary system LiCl-RbCl-H2O at 298.15 K. The standard molar Gibbs energy of formation of the two double salts from the corresponding simple salts LiCl · H2O and RbCl, as well as the standard molar Gibbs energy of formation have been determined.  相似文献   

19.
The solubilities and the densities in the aqueous ternary system (MgCl2 + MgSO4 + H2O) at 323.15 K were determined by the isothermal evaporation method. The phase diagram was drawn for this system at 323.15 K. The phase diagram consists of two invariant points, three univariant curves, and three crystallization regions corresponding to bischofite (MgCl2 · 6H2O), tetrahydrate (MgSO4 · 4H2O) and hexahydrite (MgSO4 · 6H2O). Neither double salts nor solid solution was found. Based on the Pitzer and Harvie–Weare (HW) model, the solubility equilibrium constants for the salts were fitted with the solubilities in this research work, and the solubilities of the ternary system at 323.15 K were calculated. Comparisons between the calculated and measured solubilities show that the predicted data agree well with the experimental results.  相似文献   

20.
Ternary System KN3? Ca(N3)2? H2O at 298 K The ternary system KN3? Ca(N3)2? H2O has been investigated at 298 K by means of solubility measurements and x-ray methods. A complex alkali-alkaline earth azide hydrate with the composition K2Ca(N3)4 · 4 H2O was crystallized and the stability condition defined. Lattice parameters were determined by x-ray single crystal techniques. K2Ca(N3)4 · 4 H2O crystallizes orthorhombic, a = 1876.9, b = 1094.4, c = 613.9 pm, N = 4, space group Ccca.  相似文献   

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