Solubility in the PrCl<Subscript>3</Subscript>-SmCl<Subscript>3</Subscript>-HCl-H<Subscript>2</Subscript>O System at 25°C

The solubility in the PrCl₃-SmCl₃-HCl-H₂O quaternary water-salt system was studied at 25°C along the 40% hydrochloric acid section (a system with solid solutions and discontinuity). The composition of the discontinuity point was as follows: PrCl₃ · 7H₂O, 2.33; SmCl₃ · 6H₂O, 0.11; HCl, 40.05; and H₂O, 57.51 wt %.     

Solubility in the LaCl<Subscript>3</Subscript>-LnCl<Subscript>3</Subscript>-HCl-H<Subscript>2</Subscript>O (Ln = Pr,Nd) Systems at 25°C

The solubility in the quaternary water-salt systems LaCl₃-NdCl₃-HCl-H₂O (1) and LaCl₃-PrCl₃-HCl-H₂O (2) at 25°C was studied in the section of 40 wt % hydrochloric acid, a system with a eutonic discontinuity. The composition at the point of discontinuity for the eutonic solution is the following. In system 1: 4.67 wt % LaCl₃ · 7H₂O, 0.37 wt % PrCl₃ · 7H₂O, 37.98 wt % HCl, and 56.98 wt % H₂O; in system 2: 4.37 wt % LaCl₃ · 7H₂O, 0.93 wt % NdCl₃ · 6H₂O, 37.88 wt % HCl, and 56.82 wt % H₂O.     

Solubility in the Na,Ca∥CO<Subscript>3</Subscript>,HCO<Subscript>3</Subscript>–H<Subscript>2</Subscript>O system at 25°C

Solubility in the Na,Ca∥CO₃,HCO₃–H₂O system is studied; its phase diagram at 25°C is plotted.     

Solubility in the ternary system LiCl + MgCl<Subscript>2</Subscript> + H<Subscript>2</Subscript>O at 60 and 75°C

The solubility of ternary system of lithium, magnesium and chloride and refractive indexes have been determined at 60 and 75°C, respectively. Using the experimental results, the phase diagrams of the ternary system were plotted. The single-salt Pitzer parameters of LiCl and MgCl₂ β⁽⁰⁾, β⁽¹⁾ and C ^ϕ were calculated by using the equations reported by Li Y-H and de Lima at different temperatures, respectively. On the basis of Pitzer ion-interaction model and solubility product equation for mixed electrolytes, the mixing parameters θ_{Li, Mg}, Ψ_{Li, Mg, Cl} and equilibrium constant K _sp were evaluated in this system, which were not reported in literature. A complete phase diagram of the ternary system was predicted at 60 and 75°C. The prediction of solubilities in ternary system was then demonstrated. The calculated solubilities agreed well with the experimental values.     

Interaction of components in the NaOH-TiO<Subscript>2</Subscript> · H<Subscript>2</Subscript>O-H<Subscript>2</Subscript>O system at 25°C

Solubilities in the NaOH-TiO₂ · H₂O-H₂O system at 25°C were studied. The solubility isotherm was found to have two maxima. The formation of two compounds, Na₂Ti₅O₁₁ · 10H₂O and Na₂Ti₃O₇ · 7H₂O, was established.     

Phase equilibria in the Na,K‖CO<Subscript>3</Subscript>,HCO<Subscript>3</Subscript>,F-H<Subscript>2</Subscript>O system at 25°C

Phase equilibria in the Na,K‖CO₃,HCO₃,F-H₂O system at 25°C are studied by the translation method. Twenty nine double-saturation divariant fields, 31 triple-saturation monovariant curves, and 11 quadruple-saturation points for equilibrium solid phases are distinguished in the system. The first looped phase diagram (phase complex) of the title system is designed.     

Phase equilibria in the Na,K||SO<Subscript>4</Subscript>,CO<Subscript>3</Subscript>,HCO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system at 25°C

Phase equilibria in the system Na,K|SO₄,CO₃,HCO₃-H₂O at 25°C are studied by the translation method. Thirty two double-saturation fields, 36 triple-saturation monovariant curves, and 13 quadruple-saturation points are distinguished in the system. The first closed phase diagram (phase complex) of the title system is designed.     

Na<Subscript>2</Subscript>MoO<Subscript>4</Subscript>-K<Subscript>2</Subscript>MoO<Subscript>4</Subscript>-H<Subscript>2</Subscript>O system at 25°C

Phase formation in the Na₂MoO₄-K₂MoO₄-H₂O system was studied at 25°C. Two incongruently saturating complex phases are formed in this system: Na₃K(MoO₄)₂ · 9H₂O and NaK₃(MoO₄)₂. The densities, refractive indices, and dynamic viscosities of saturated solutions of the system were determined; molar volume and ionic strength isotherms were calculated. A correlation relation was found between solubility and solution properties in the system. The indicated double salts were recovered and characterized using chemical analysis, powder X-ray diffraction, complex thermal analysis, and IR spectroscopy.     

The NaCl–AlCl<Subscript>3</Subscript>–HCl–H<Subscript>2</Subscript>O system at 25°С

Solubility was studied in the system NaCl–AlCl₃–HCl–H₂O at 25°C in the section 28 wt % HCl. The system is of the eutonic type and has an extensive sodium chloride crystallization region. The composition of the eutonic solution is the following, wt %: NaCl, 0.47; AlCl₃ ? 6H₂O, 8.88; HCl, 25.38; and H₂O, 65.27. The lines of saturated solutions were approximated by polynomial equations.     

Phase diagram of the NaCl–MgCl<Subscript>2</Subscript>–H<Subscript>2</Subscript>O system at 25–75°C and its application for MgCl<Subscript>2</Subscript> · 6H<Subscript>2</Subscript>O purification

The co-saturation line for the solid phases NaCl_(s) and MgCl₂ · 6H₂O_(s) in aqueous solution has been measured by a phase equilibrium at various temperatures. It was found that the Y _b (Y _b = w(NaCl)/(w(NaCl) + w(MgCl₂))) value of the co-saturation line increase with increasing temperature. A new recrystallization approach has been suggested for the purification of MgCl₂ · 6H₂O_(s) containing quite amount of impurity NaCl, i.e., dissolving the crude sample at low temperatures, followed by evaporating and phase separating at high temperatures. Applying the proposed approach a crude MgCl₂ · 6H₂O_(s) sample can be purified to the level of Y _b = 0.17% by only one crystallization process.     

Phase equilibria in a ternary fullerenol-d(C<Subscript>60</Subscript>(OH)<Subscript>22–24</Subscript>)–SmCl<Subscript>3</Subscript>–H<Subscript>2</Subscript>O system at 25°C

The solubility in a ternary fullerenol-d (C₆₀(OH)_22–24)–SmCl₃–H₂O system at 25°C is studied via isothermal saturation in ampules. The solubility diagram is shown to be a simple eutonic one that consists of two branches corresponding to the crystallization of fullerenol-d (C₆₀(OH)_22–24 · 30H₂O) and samarium(III) chloride SmCl₃ · 6H₂O crystallohydrates and contains one nonvariant eutonic point corresponding to saturation with both crystallohydrates. The long branch of C₆₀(OH)_22–24 · 30H₂O crystallization shows the effect of fullerenol-d salting out of saturated solutions; in contrast, the short branch of SmCl₃ · 6H₂O crystallization shows the pronounced salting-in effect of samarium(III) chloride.     

Solubility in the LaCl3-YbCl3-HCl-H2O System at 25°C

Solubility has been studied in the LaCl₃-YbCl₃-HCl-H₂O water-salt system at 25°C along the (40 ± 0.2)% HCl section; this is a eutonic-type system. The composition of the eutonic solution is as follows (wt %): LaCl₃ · 7H₂O, 4.67, YbCl₃ · 6H₂O, 0.37; HCl, 37.98; and H₂O, 56.98.     

Solubility in the system 2HCOONa + CaCl<Subscript>2</Subscript> ⇄ (HCOO)<Subscript>2</Subscript>Ca + 2NaCl–H<Subscript>2</Subscript>O

Phase and conversion equilibria in the quaternary reciprocal water–salt system 2HCOONa + CaCl₂ ? (HCOO)₂Ca + 2NaCl–H₂O at 25°C were studied for the first time to determine the concentration parameters of the production of calcium formate from sodium formate.     

Modeling of the composition of the eutonic solution in the NaCl–AlCl<Subscript>3</Subscript>−SrCl<Subscript>2</Subscript>–HCl–H<Subscript>2</Subscript>O system at 25°С and its experimental confirmation

The solubility was studied in the system NaCl–AlCl₃?SrCl₂–HCl–H₂O of the eutonic type at 25°C in the section 28 wt % HCl. It was determined that it is possible to derive equations of the solubility surface of crystallizing salts and to calculate the composition of the eutonic solution.     

Formation of nanocrystals in the ZrO<Subscript>2</Subscript>–H<Subscript>2</Subscript>O system

Formation of zirconia nanocrystals in the course of thermal treatment of an X-ray amorphous zirconium oxyhydroxide was studied. It was shown that the formation of tetragonal and monoclinic polymorphs of ZrO₂ in the temperature range from 500 to 700°C occurs owing to dehydration and crystallization of amorphous hydroxide. An increase of the temperature up to 800°C and higher activates mass transfer processes and, as a result, activates the nanoparticle growth and increases the fraction of the phase based on monoclinic modification of ZrO₂ due to mass transfer from the nanoparticles with the non-equilibrium tetragonal structure. Herewith, formed ZrO₂ nanocrystals with monoclinic structure have a broad size distribution of crystallites, and the average crystallite size after thermal treatment at 1200°C for 20 min is about 42 nm.     

Solution-solid phase equilibrium in the systems MgBr<Subscript>2</Subscript>-NR<Subscript>4</Subscript>Br-H<Subscript>2</Subscript>O at 25°C (R = Me,Et, Bu)

Solubility in the ternary systems MgBr₂-NR₄Br-H₂O (R = Me, Et, Bu) at 25°C was determined by the isothermal saturation method. A comparative analysis of phase diagrams was fulfilled. The results obtained were interpreted in the context of competition between hydration and association processes in water-salt systems. The structure of double salts NMe₄Br·MgBr₂·6H₂O and NEt₄Br·MgBr₂·8H₂O was determined, and the possibility for predicting compositions of crystallizing double salts on the basis of crystallographic characteristics of ions was analyzed.     

Solubilities of salts in the ternary systems NaCl + CaCl<Subscript>2</Subscript> + H<Subscript>2</Subscript>O and KCl + CaCl<Subscript>2</Subscript> + H<Subscript>2</Subscript>O at 75°C

The solubility in the NaCl-CaCl₂-H₂O and KCl-CaCl₂-H₂O systems were determined at 75°C and the phase diagrams and the diagram of physicochemical property vs composition were plotted. One invariant point, two univariant curves, and two crystallization zones, corresponding to potassium chloride, dihydrate (CaCl₂ · 2H₂O) showed up in the phase diagrams of the ternary systems. The mixing parameters θ_{M, Ca} and Ψ_{M, Ca, Cl} (M = Na or K) and equilibrium constant K _sp were evaluated in NaCl-CaCl₂-H₂O and KCl-CaCl₂-H₂O systems by least-squares optimization procedure, in which the single-salt Pitzer parameters of NaCl, KCl, and CaCl₂ β⁽⁰⁾, β⁽¹⁾, β⁽²⁾, and C ^Φ were directly calculated from the literature. The results obtained were in good agreement with the experimental data.     

Simulating equilibrium processes in the Ga(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>–H<Subscript>2</Subscript>O–NaOH system

Equilibrium processes in the Ga(NO₃)₃–H₂O–NaOH system are simulated with allowance for the formation of precipitates of various compositions using experimental data from potentiometric titration and theoretical studies. The values of the instability constants are calculated along with the stoichiometric compositions of the resulting compounds. It is found that pH ranges of 1.0 to 4.3 and 12.0 to 14.0 are best for the deposition of gallium chalcogenide films.     

Phase formation in the system Zn(VO<Subscript>3</Subscript>)<Subscript>2</Subscript>–HCl–VOCl<Subscript>2</Subscript>–H<Subscript>2</Subscript>O

The phase and chemical compositions of precipitates formed in the system Zn(VO₃)₂–HCl–VOCl₂–H₂O at pH 1?3, molar ratio V⁴⁺: V⁵⁺ = 0.1?9, and 80°C were studied. It was shown that, within the range 0.4 ≤ V⁴⁺: V⁵⁺ ≤ 9, zinc vanadate with vanadium in a mixed oxidation state forms with the general formula Zn_xV⁴⁺ _yV⁵⁺ _2-yO₅ ? nH₂O (0.005 ≤ x ≤ 0.1, 0.05 ≤ y ≤ 0.3, n = 0.5?1.2). Vanadate Zn_xV₂O₅ ? nH₂O with the maximum tetravalent vanadium content (y = 0.30) was produced within the ratio range V⁴⁺: V⁵⁺ = 1.5?9.0. Investigation of the kinetics of the formation of Zn_xV₂O₅ ? nH₂O at pH 3 determined that tetravalent vanadium ions VO2+ activate the formation of zinc vanadate, and its precipitation is described by a second-order reaction. It was demonstrated that, under hydrothermal conditions at pH 3 and 180°C, zinc decavanadate in the presence of VOCl₂ can be used as a precursor for producing V₃O₇ ? H₂O nanorods 50–100 nm in diameter.