Study on phase diagrams and properties of solutions in ternary systems Li+,K+(Mg2+)/SO42--H2O at 25℃

Solubilities of ternary systems Li+,K+/SO42--H2O (1) and Li+,Mg2+/SO42-H2O (2) were investigated by isothermal method at 25℃. 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℃. 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.     

Li~+,Na~+//+ Cl~-,B_4O_7~(2-)-H_2O Reciprocal Quaternary System Solubility Phase Diagrams

The solubilities, refraction indices and densities of saturated solution of Li+ , Na+ Cl- ,B4O72- -H2O reciprocal quaternary system at 0℃, 25℃ and 50℃ were determined by using isotherm method. Using total concentration of all the salts in solution as concentration coordinate(ordinate) the isothermal stereogram of solubility of the system was drawn. The results showed that the stable salt-pair of the system is Na2Cl2-Li2B4O7 and that there are two isothermal invariant points, eutonic ponit E and inversion point Pcorresponding to the eqilbria: solution (E) LiCl·H2O (at 25, 50℃) or LiCl·2H2O (at 0℃) + NaCl + Li2B4O7 · 3H2O and solution (P) + Na2-B4O7·1OH2O NaCl + Li2B4O7·3H2O and the crystallization fields ofborates are much larger than those of chlorides.     

Measurement and Correlation of Equilibrium Data for Aqueous Two-phase System Ethanol＋Water＋ K2HPO4

The isothermal solubility data of aqueous two-phase system ethanol water K2HPO4 were determined with the turbidity titration method at 303.2 K. The binodal curves were described by using the Mistry equation very well. An experimental procedure for measuring the liquid-liquid equilibrium data of the aqueous two-phase system was proposed, in which the concentrations of the coexisting phases were determined with the corresponding densities of the solution. The tie lines were satisfactorily described by using the Othmer-Tobias and Bancroft equations.     

Solid-liquid Metastable Equilibria in Quaternary System Li_2SO_4+Li_2CO_3+Li_2B_4O_7+H_2O at 288 K

Metastable equilibrium solubilities and densities of quaternary system Li2SO4+Li2CO3+ Li2B4O7+H2O at 288 K were determined by isothermal evaporation method. According to the experimental data, the metastable equilibrium phase diagram was plotted. The metastable phase diagram had one invariant point F, three double saturated liquid curves E1F, E2F and E3F, and three crystallization fields corresponding to Li2SO4·H2O, Li2CO3 and LiBO2·8H2O. It was found that lithium sulphate(Li2SO4) had the highest concentrat...     

Solid-liquid Equilibria in the Quaternary System Na＋, K＋//Br-, B4O72--H2O at 298 K

According to the compositions of the underground gasfield brines in the west of Sichuan Basin, the solu- bilities and densities of the solid-liquid equilibria in the quaternary system Na＋, K＋//Br-, B4O72--H2O at 298 K were determined by the method of isothermal solution saturation. From the experimental data, the phase diagram, water content diagram and density-composition diagram were obtained. This quaternary system is of simple eutectic type, without double salt and solid solution. There are two invariant points, five univariant curves, four fields of crystalli- zation in the system. The equilibrium solid phases are Na2BaO7·10H20, K2B4O7·4H2O, NaBr·2H2O and KBr. Na2B4O7·10H2O has a larger crystallization field, and NaBr·2H2O has a smaller crystallization field. It is also found that bromide has the salting-out effect on borate in the quaternary system Na＋, K＋//Br-, B4O72--H2Oat 298 K.     

Phase Equilibrium of Quaternary System Cd~(2+)//Cl~-,SO_4~(2-),NO_3~--H_2O at 298 K

Solid-liquid equilibrium of quaternary system Cd2+//Cl-, SO42-, NO3--H2O at 298 K was studied by means of an isothermal solution saturation method. Experimental results indicate that there are three univariant curves BE, AE and CE, one invariant point E and three crystallization fields in the quaternary system. The quaternary system belongs to a simple type, and there are no double salts or solid solution existing. The crystallization zones of equilibrium solid phases are CdCl2·5/2H2O(AEB field), 3CdSO4·8H2...     

三元系RbCl-C2H5OH-H2O液固相平衡及其物化性质研究

The isothermal solubility and physico-chemical properties (density, refractive index) of ternary system RbCl-EtOH-H₂O at 25℃ and 50℃ have been firstly investigated by means of self-made micro-equilibrium and sampling apparatus .The compositions of liquid and solid at equilibrium state were determined, and the problem of analysis of ethanol content in system was properly solved. The phase diagram was drawn by the TPD phase-diagram computer program developed by us. Three empirical formulae were proposed to correlate the solubility, density and refractive index respectively. No demixing phenomena was observed in the range of temperature related in this study.     

离子相互作用模型在HCl-LiCl-MgCl2-H2O体系20˚C时溶解度预测中的应用

Component solubility in HCl-LiCl-MgCl2-H2O system of high ionic strength at 20℃ was predicted by using the Pitzer＇s ion-interaction model. The results indicated that the model supplied a very good prediction of the component solubility of the system mentioned above. The values of parameters of β^0, β^1 and C^＊ of HCl, LiCl and MgCl2 were obtained from optimization of literature data, while those of θMN and ψMNX were calculated from a least-squares optimization procedure to couple activity coefficient with solubility data. According to the ion-interaction model, no additional parameters need to be determined for more complex systems. The study provided theoretical basis for the manufacture process, which was proposed by Gao and employed to extract LiCl and MgCl2·6H2O from salt lake brine.     

三元体系KCl-SrCl_2-H_2O 25℃相平衡研究

Phase equilibria in the ternary system KCl-SrCl2-H2O at 25 ℃ was studied by using the isothermal method. Density and refractive index of the solution were also determined. The phase diagram was plotted according to the experimental data. In the equilibrium phase diagram of KCl-SrCl2-H2O, there is one invariant point, two univariant curves and two regions of crystallization: KCl and SrCl2·6H2O. In the invariant point, the composition of the liquid phase (mass fraction, wB) was wKCl 7.22%, wSrCl232.31%, the solid phase was KCl and SrCl2·6H2O. Neither double salts nor solid solutions between KCl and SrCl2·6H2O were found, and dehydration of SrCl2·6H2O didn′t occur in the system. The system is a simple eutectic type.     

Kinetics and rate-limiting mechanisms of dolomite dissolution at various CO_2 partial pressures

Techniques of rotating-disk and catalyst were used in investigating the kinetics of dolomite dissolution in flowing CO2-H2O system. Experiments run in the solutions equilibrated with various CO2 partial pressures (PCO2) from 30 to 100000 Pa. It shows that dissolution rates of dolomite are related with rotating speeds at conditions far from equilibrium. This was explained by modified diffusion boundary layer (DBL) model. In addition, the dissolution rates increase after addition of carbonic anhydrase (CA) to solutions, where the CA catalyzes CO2 conversion. However, great differences occur among various CO2 partial pressures. The experimental observations give a conclusion that the modified DBL model enables one to predict dissolution rates and their behaviour at various PCO2 with satisfactory precision at least far from equilibrium.     

Die Kristallstruktur von K2S3 und K2Se3

The Crystal Structure of K₂S₃ and K₂Se₃ Well formed crystals of K₂S₃ and K₂Se₃ were obtained by reaction of the elements in liquid ammonia at 500 bar and 150°C. The substances are both orthorhombic, space group Cmc2₁. Cell constants are: The structure contains S₃^2?(Se₃^2?) polyanions, with S? S? S(Se? Se? Se) angles of 105.4(102.5)°. The S? S(Se? Se) distance is 2.083(2.383) Å.     

Die Systeme K2NaAlF6/Na2SO4 und K2NaAlF6/K2SO4 Phasendiagramme und Alkaliionenleitung

On the Systems K₂NaAlF₆/Na₂SO₄ and K₂NaAlF₆/K₂SO₄: Phase Diagrams and Alkali Ion Conductivity The phase diagrams of the K₂NaAlF₆/Na₂SO₄ and K₂NaAlF₆/K₂SO₄ systems have been determined by means of thermal, x-ray powder and electrochemical methods in the solidus-liquidus and the sub-solidus region, as well. At the optimum combination of parameters, the alkaliion conductivity increased by about three orders of magnitude upon doping K₂NaAlF₆ with Na₂SO₄ and/or K₂SO₄.     

Ultraviolet bands of Na2 and K2

The ultraviolet spectra of Na₂ and K₂ molecules have been investigated. These studies were made in absorption in the second order of a 3.4 m Ebert Spectrograph with a reciprocal dispersion of 2.6 Å/mm. A number of new bands in the spectra of both the molecules not previously reported have been observed. Computer methods have been used to calculate the term values and to evaluate molecular constants.     

Zum System K2O/PbO. Zur Kenntnis von K2Pb2O3

On the System K₂O/PbO: The Crystal Structure of K₂Pb₂O₃ Orange-coloured single crystals of K₂Pb₂O₃ crystallize by means of 4-circle-Diffractometer data (237 of 238 possible hkl, R = 5.9₉%, MoKα) cubic with a = 8.41₉ Å, Z = 4, in space group I2₁3?T⁵, parameter see text. We find a superstructure of the perovskite type of structure, where, concerning the formula KPbO_3/2, half of the O^2? ions are omitted systematically, without loosing the 3-Dimensional arrangement of order. Pb²⁺ is surrounded by 3 K⁺ by 6 O^2? and O^2? by 2 Pb²⁺ and 4 K⁺. The Madelung Part of the Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, are calculated and discussed.