Physicochemical Analysis of the System Zr(SO<Subscript>4</Subscript>)<Subscript>2</Subscript>–Na<Subscript>2</Subscript>SO<Subscript>4</Subscript>–H<Subscript>2</Subscript>SO<Subscript>4</Subscript>–H<Subscript>2</Subscript>O at 25°С

The solubility in the quaternary water–salt system Zr(SO₄)₂ · 4Н₂О–Na₂SO₄–H₂SO₄–H₂O at 25°C was studied. It was found that, in the system, there is crystallization of not only Na₂SO₄ and Zr(SO₄)₄ · 4H₂O, but also sodium sulfate zirconates Na₂Zr(SO₄)₂(OH)₂ · 0.3H₂O, Na₄Zr(SO₄)₄ · 3H₂O, and Na₂Zr(SO₄)₂ · 3H₂O and two new compounds, S₁ and S₂, which are presumably Na₂ZrO(SO₄)₂ · 2H₂O and Na₂Zr₂O₂(SO₄)₃ · 6H₂O.     

Multicomponent systems LiCl–LiBr–Li<Subscript>2</Subscript>SO<Subscript>4</Subscript> and LiCl–LiBr–Li<Subscript>2</Subscript>SO<Subscript>4</Subscript>–Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>

Phase equilibria in the LiCl–LiBr–Li₂SO₄ ternary system and the LiCl–LiBr–Li₂SO₄–Li₂MoO₄ quaternary system were studied by differential thermal analysis. The compositions and temperatures of minima in the ternary and quaternary systems were determined to be (31.2 mol % LiCl, 46.8 mol % LiBr, 22.0 mol % Li₂SO₄, 460°C) and (25.2 mol % LiCl, 30.2 mol % LiBr, 14.6 mol % Li₂SO₄, 30.0 mol % Li₂MoO₄, 411°C), respectively.     

Synthesis of nanopowders and physicochemical properties of ceramic matrices of the LaPO<Subscript>4</Subscript>–YPO<Subscript>4</Subscript>–(H<Subscript>2</Subscript>O) and LaPO<Subscript>4</Subscript>–HoPO<Subscript>4</Subscript>–(H<Subscript>2</Subscript>O) systems

Sol-gel method was used to synthesize nanosize powders in the LaPO₄–YPO₄–(H₂O) and LaPO₄–HoPO₄–(H₂O) systems. Dense ceramic samples with high microhardness (up to 25 GPa) were formed from these powders by sintering at temperatures of up to 1600°C. The isomorphic capacity of the monoclinic LaPO₄ matrix for the second component (yttrium or holmium) simulating radioactive nuclides of the actinide-rare-earth fraction was found to be high. The composites are stable in aqueous solutions, which is indicated by the low concentration of lanthanum and yttrium ions during leaching test (~10^–7 g L^–1). The results obtained in the study can be used to develop new high-efficiency ceramic matrices for solidification of the actinide-rare-earth fraction of liquid wastes formed in processing of the spent nuclear fuel.     

Synthesis and Crystal Structure of [Co(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>](C<Subscript>19</Subscript>H<Subscript>17</Subscript>O<Subscript>4</Subscript>SO<Subscript>3</Subscript>)<Subscript>2</Subscript>⋅8H<Subscript>2</Subscript>O

The title compound, cobalt 4′,7-diethoxylisoflavone-3′-sulfonate([Co(H₂O)₆](X)₂⋅8H₂O, X = C₁₉H₁₇O₄SO₃) was synthesized and its structure was determined by single-crystal X-ray diffraction analysis. It crystallizes in the triclinic space group P-1 with cell parameters a = 9.026(3) Å, b = 16.431(5) Å, c = 18.195(6) Å, α = 72.289(4)^∘, β = 87.498(4)^∘, γ = 82.775(5)^∘, V = 2550.1(13) Å⁻³, D_c = 1.419 Mg m⁻³, and Z = 2. The results show that the title compound consists of one cobalt cation, six coordinated water molecules, eight lattice water molecules, and two 4′,7-diethoxylisoflavone-3′-sulfonate anions, C₁₉H₁₇O₄SO⁻₃. Two anions have different conformations. Twelve H atoms of six coordinated water molecules, as donors, form hydrogen bonds with four oxygen atoms of sulfo-groups of two anions and eight oxygen atoms of eight lattice water molecules. In addition, π < eqid1 > ⋅ < eqid2 > π stacking interactions exist in the crystal structure, which together with hydrogen bonds lead to supramolecular formation with a three-dimensional network.     

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.     

Glass Formation in the Al<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript>–(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>SO–H<Subscript>2</Subscript>O System

The glass formation in the Al₂(SO₄)₃–(CH₃)₂SO–H₂O system was found for the first time. The competitive ability of ligands, dimethyl sulfoxide and water (which are strong donors), for entering the first coordination sphere of aluminum is considered. The possibility of mixed coordination of (CH₃)₂SO (via sulfur and oxygen atoms) in the first coordination sphere of aluminum with retention of the glass-forming ability of the sample was suggested on the basis of IR spectral study.     

Synthesis and X-ray diffraction study of Li(H<Subscript>3</Subscript>O)[UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)] · H<Subscript>2</Subscript>O

Single crystals of Li(H₃O)[UO₂(C₂O₄)₂(H₂O)] · H₂O (I) have been synthesized and studied by X-ray diffraction. Compound I crystallizes in the monoclinic crystal system with the unit cell parameters: a = 7.1682(10) Å, b = 29.639(6) Å, c = 6.6770(12) Å, β= 112.3(7)°, space group P 2₁/c, Z = 4, R = 4.36%. Structure I contains discrete mononuclear groups [UO₂(C₂O₄)₂(H₂O)]^2? ascribed to the crystal-chemical group AB ₂ ⁰¹ M¹ (A = UO₂ ²⁺, B⁰¹ =C₂O ₄ ^2? , M¹ = H₂O), which are “cross-linked” by the lithium ions into infinite layers {Li(UO₂)(C₂O₄)₂(H₂O)₂}^? perpendicular to [010]. The hydroxonium ions are located between adjacent uranium-containing layers. A hydrogen bond system involving water molecules, oxalate ions, and hydroxonium combines the anionic layers into a three-dimensional framework.     

Solid-Liquid Equilibria in the Quaternary Systems KCl–MgCl<Subscript>2</Subscript>–SrCl<Subscript>2</Subscript>–H<Subscript>2</Subscript>O and NaCl–KCl–SrCl<Subscript>2</Subscript>–H<Subscript>2</Subscript>O at 348 K

Solid-liquid equilibria in the quaternary systems KCl–MgCl₂–SrCl₂–H₂O and NaCl–KCl–SrCl₂–H₂O at 348 K were measured by the isothermal solution saturation method. The composition of the equilibrium solid phase, solubilities of salts, and densities of saturated solution in the two systems were determined. Phase diagrams, water content diagrams and solution density diagrams of quaternary systems were plotted according to experimental data. The phase diagram of the quaternary system NaCl–KCl–SrCl₂–H₂O has one invariant point, three univariant curves as the boundary of NaCl, KCl and SrCl₂ · 2H₂O. This phase diagrams were simple co-saturation type without complex salt and solid solution. For the quaternary system KCl–MgCl₂–SrCl₂–H₂O, one complex salt KCl · MgCl₂ · 6H₂O (Car) had been found in this system, consisted of five univariant curves, two invariant points and four crystallization regions of MgCl₂ · 6H₂O (Bis), KCl, SrCl₂ · 2H₂O and KCl · MgCl₂ · 6H₂O. And the densities transformation rules were simply discussed. Simultaneously, the solubilities and densities data in invariant point of the quaternary system NaCl–KCl–SrCl₂–H₂O had been compared with the experimental data of previous researchers.     

Crystal structure of Na<Subscript>3</Subscript>(NH<Subscript>4</Subscript>)<Subscript>2</Subscript>[Ir(SO<Subscript>3</Subscript>)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>]·4H<Subscript>2</Subscript>O

The complex Na₃(NH₄)₂[Ir(SO₃)₂Cl₄]·4H₂O was examined with single crystal X-ray diffraction and IR spectroscopy. Crystal data: a = 7.3144(4) Å, b = 10.0698(5) Å, c = 12.3748(6) Å, β = 106.203(1)°, V = 875.26(8) ų, space group P2₁/c, Z = 2, d _calc = 2.547 g/cm³. In the complex anion two trans SO ₃ ^2? groups are coordinated to iridium through the S atom. The splitting of O-H bending vibrations of crystallization water molecules and N-H ones of the ammonium cation is considered in the context of different types of interactions with the closest neighbors in the structure.     

Solubility and stability of (NH<Subscript>4</Subscript>)<Subscript>2</Subscript>SO<Subscript>4</Subscript>·H<Subscript>2</Subscript>O<Subscript>2</Subscript> in organic and aqueous-organic media

Solubility and stability of (NH₄)₂SO₄·H₂O₂ in organic solvents (glycerol, ethylene glycol, TOSOL-A40 OM antifreeze), in mixtures of an organic solvent and water, and in pure water was studied. Crystallographic properties of the ammonium sulfate precipitating from aqueous-organic solvents and aqueous solutions in various time intervals and differing from ordinary (NH₄)₂SO₄ in solubility and one of crystallographic parameters were analyzed.     

Synthesis and structure of the [Co(NioxH)<Subscript>2</Subscript>(Thio)<Subscript>2</Subscript>]<Subscript>2</Subscript>SO<Subscript>4</Subscript>·2H<Subscript>2</Subscript>O complex compound

A new Co(III) complex of 1,2-cyclohexanedionedioxime and thiocarbamide with an SO ₄ ^2? anion and solvation water molecules in the outer sphere has been synthesized and its structure has been defined. Orthorhombic crystals, a = 11.659(2) Å, b = 26.448(5) Å, c = 30.142(6) Å, V = 9295(3) Å ³, Z = 8, d_calc = 1.599 g/cm³, space group Pbca; final R index is 0.0578 for 8221 reflections with I > 2σ(I). In the octahedral Co(III) complex, two 1,2-cyclohexanedionedioxime residues lie in the equatorial plane, while two thiocarbamide molecules are in the axial plane. Intramolecular bonds: N-H…O and O-H…O type hydrogen bonds and π-π interactions that stabilize the complex cations. In crystal, the components are linked by N-H…O and O-H…O hydrogen bonds into a 3D framework.     

Synthesis,Structure and Property of Oxo-Bridged Binuclear Iron(III) Complex [Fe(phen)(H<Subscript>2</Subscript>O)<Subscript>3</Subscript>]<Subscript>2</Subscript>O⋅2SO<Subscript>4</Subscript>

An oxo-bridged binuclear iron(III) complex, [Fe(phen)(H₂O)₃]₂O2SO₄, has been synthesized and structurally characterized by elemental analysis (EA), IR, TG-DSC and X-ray. Its crystal structure has been determined by X-ray crystallography. It crystallizes in the orthorhombic system, space group P2₁2₁2, with lattice parameters a = 17.650(4), b = 8.5133(17), c = 9.971(2) Å; V = 1498.2(5) ų, _calcd = 1.763 g/cm³ and Z = 4 for R₁ = 0.0601. The crystal structure indicated that two octahedrally coordinated iron(III) ions bridged with oxygen atoms formed a non-linear complex. The bond angle of Fe–O–Fe is 163.9(4). The data of EA and IR are in good agreement with the crystal structure. The thermal gravity (TG) data indicate that there are four decomposition steps with three endothermic peaks. The final product of the thermal decomposition may be Fe(C₂H₈N₂)SO₄.     

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.     

System RbF–RbBr–Rb<Subscript>2</Subscript>SO<Subscript>4</Subscript>

The three-component system RbF–RbBr–Rb₂SO₄ has been studied by differential thermal analysis (DTA). The melting temperatures and compositions corresponding to a eutectic point and a peritectic point have been determined. Invariant, monovariant, and divariant equilibrium states are described.     

Crystal structure and quantum chemical investigation of [Cd(NTO)<Subscript>4</Subscript>Cd(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>] · 4H<Subscript>2</Subscript>O

[Cd(NTO)₄Cd(H₂O)₆] •4H₂O was synthesized by mixing the aqueous solution of 3-nitro-1, 2,4-triazol-5-one (NTO) and cadmium carbonate. The single crystal structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, space group C2/c with crystal parameters of a = 2.1229(3) nm, b = 0.6261(8) nm, = 2.1165(3) nm, β= 90.602 (3)°, V= 2.977(6) nm₃, Z = 4, D_c = 2.055 g • cm_-3, μ = 15.45 cm_-1 and F(000) = 1824. 2523 observable independent reflections with F₀4σ(F₀) were used for the determination and refinement of the crystal structure. Lorentz-polarization and absorption correction were applied. The final R is 0.0282 and wR = 0.0792. The analytical results show that the Cd⁺² has two kinds of coordinate bonds in one crystal. One Cd⁺² coordinates with 4 NTO anions and another coordinates with 6 water molecules to form a binucleate complex with a structure of tetrahedron and tetragonal bipyramid, respectively. By using SCF-PM3-MO method, the electron structure of cadmium complex of NTO has been calculated. The analysis of the calculated results shows that when [Cd(NTO)₄Cd(H₂O)₆] • 4H₂O is heated, the crystallization waters will be dissociated first and the ligand waters second and NO₂ group has priority of leaving when NTO⁻ is decomposed. Analysis of the energy level and composition of localized molecular orbitals indicates that both the two Cd²⁺ bond to the coordinating atom with 5s     

Transformations of CO<Subscript>2</Subscript> in Two-Phase Systems C<Subscript>8</Subscript>F<Subscript>18</Subscript>–H<Subscript>2</Subscript>O and C<Subscript>6</Subscript>F<Subscript>6</Subscript>–H<Subscript>2</Subscript>O

The transformation of carbon dioxide in aqueous emulsions of perfluorons in the presence of oxygen in the air results in the formation of a mixture of oxalic acid and a minor set of organic compounds C₄–C₈. The maximum CO₂ consumption occurs in the emulsion with the C₈F₁₈: H₂O vol/vol ratio of 1: 0.42 at pH 2.4; the H₂C₂O₄ yield is 11 mol %.     

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.     

Metastable Phase Equilibrium in the Aqueous Ternary System K<Subscript>2</Subscript>SO<Subscript>4</Subscript>+MgSO<Subscript>4</Subscript>+H<Subscript>2</Subscript>O at (288.15 and 308.15) K

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.     

Interpretation of partial thermal decomposition mechanism of Dy<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript>·8H<Subscript>2</Subscript>O

Partial dehydration of Dy₂(SO₄)₃·8H₂O was studied employing TG, DSC, D.C. electrical conductivity and spectroscopic techniques. The possible mechanism for the loss of water molecules (partial dehydration) was found to be random nucleation obeying Mapel equation based on TG trace. The DSC traces are supports the results of TG traces and are also utilized to understand the enthalpy changes accompanying the partial dehydration and phase transition accompanying the dehydrated samples. D.C. electrical conductivity studies are attempted to supplement these TG studies. Attempts are made to explain the structural changes accompanying dehydration on the basis of infrared spectra and X-ray diffraction and scanning electron microscopic studies.