Thermal analysis of kidney stones and their characterization

Thermal decomposition and structural characterization of three human kidney stones (KS1–KS3) extracted from patients of Eastern Bohemia have been carried out using X-ray powder diffraction systems (XRD), scanning electron microscope with energy dispersive X-ray micro analyser (SEM-EDX) and differential thermal analysis (DTA). The samples KS1 and KS2 solely consisted of calcium oxalate monohydrate (a.k.a. whewellite, CaC₂O₄·H₂O). The third sample, KS3, was formed from calcium oxalate dihydrate (weddellite, CaC₂O₄·2H₂O), calcium oxalate monohydrate, and hydroxyapatite (HA, Ca₁₀(PO₄)₆(OH)₂). Thermal measurements were carried out in the range between room temperature and 1,230 °C. XRD analysis was utilized to investigate the change of phases at 800 and 1,230 °C.     

Thermodynamics of the thermal decomposition of calcium oxalate monohydrate examined theoretically

Geometries and energies of isolated CaC₂O₄·H₂O, CaC₂O₄, CaCO₃, CaO, H₂O, CO and CO₂ were determined at the ab initio level using effective core potential valence basis sets of doublezeta quality, supplemented with polarization functions. The effects of electron correlation were taken into account at the second order Møller-Plesset level of theory. For CaC₂O₄·H₂O, the correlation for the basis set superposition error was also included. Common routines were employed to evaluate entropies, heat capacities, as well as enthalpies and free enthalpies of formation of all entities. The enthalphies and free enthalpies of consecutive dehydration of CaC₂O₄·H₂O, decarbonylation of CaC₂O₄ and decomposition of CaCO₃ towards CaO and CO₂ were determined on the basis of avialable data from the literature or those predicted thoretically. Assuming that upon all the above mentioned processes the system maintains equilibrium, the fractions reacted, enthalpy changes and differential dependencies of thesevs. temperature were derived and compared with experimental thermoanalytical data.     

Synthesis of different polymorphic modifications of calcium oxalate by electrodeposition

Different hydrates of calcium oxalate have been electrodeposited by electrogeneration of acid at the anode from an EDTA-stabilized calcium nitrate bath containing dissolved oxalate ions. The deposition is controlled by varying the bath pH, temperature, and current density. Formation of metastable CaC₂O₄·2H₂O is favored at high current densities at ambient temperature, whereas the thermodynamically stable CaC₂O₄·H₂O is formed at elevated bath temperatures. Both the polymorphs show oriented growth with respect to the substrate normal under different deposition conditions.     

Mössbauer spectrometica analysis of thermal decomposition products of phosphate and oxalate coatings on steel

The deterioration of zinc, zinc—calcium and manganese phosphate coatings and oxalate coatings on steel on heating was investigated by conversion electron Mössbauer spectrometry. and the chemical change of the coatings was analysed on the basis of the thermal characteristics of Zn₃(PO₄)₂·4H₂O, Zn₂Fe(PO₄)₄·4H₂O, CaZn₂(PO₄)₂·2H₂O, Fe₃(PO₄)₂·8H₂O. (Mn, Fe)₅H₂(PO₄)₄·4H₂O and FeC₂O₄·2H₂O. The steel substrate beneath the coatings influenced the thermal decomposition and evaporation of coating materials under the various heating atmospheres. The heat resistance of these coatings and the state of the substrate were also investigated.     

Phase formation in the ZrO(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript>-CsF-H<Subscript>2</Subscript>O system at low concentration of the phosphorus-containing component

The ZrO(NO₃)₂-H₃PO₄-CsF-H₂O system was studied at 20°C along the section at a molar ratio of PO₄³⁻/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO₂ concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated for the first time: crystalline fluorophosphates CsZrF₂PO₄ · H₂O, amorphous oxofluorophosphate Cs₂Zr₃O₂F₄(PO₄)₂ · 3H₂O, and amorphous oxofluorophosphate nitrate CsZr₃O_1.25F₄(PO₄)₂(NO₃)_0.5 · 4.5H₂O. The compound Cs₃Zr₃O_1.5F₆(PO₄)₂ · 3H₂O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following new compounds was established: Cs₂Zr₃O_1.5F₅(PO₄)₂ · 2H₂O, Cs₂Zr₃F₂(PO₄)₄ · 4.5H₂O, and Zr₃O₄(PO₄)_1.33 · 6H₂O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical, thermal, and IR spectroscopic analyses.     

Transformation of Calcium Dihydrogenphosphate in Mixtures with Apatite Concentrate Upon Heating

Abstract

The present work is related to an investigation of the chemistry of the phosphoric acid-thermal processing of apatite into a phosphate animal feed aupplement. Dried mixtures of H₃PO₄ with apatite concentrates of various mineral content and chemical composition as well as mixtures based on Ca(H₂PO₄2)₂ · H₂O, Ca₂P₂O₇ and Ca(PO₃)₂ were used. The investigation was carried out by chemical, thermal, chromatographic and X-ray diffraction methods.     

Phase formation in the ZrO(NO3)2-H3PO4-CsF(HF)-H2O system

The phase formation in the system ZrO(NO₃)₂-H₃PO₄-CsF(HF)-H₂O was studied at the molar ratio CsF/Zr = 1 along the sections PO ₄ ^3? /Zr = 0.5 and 1.5 at a ZrO₂ concentration in the initial solution of 2?C14 wt %. The following compounds were isolated: Cs₅Zr₄F₂₁ · 3H₂O, CsZr₂(PO₄)₃ · 2HF · 2H₂O, CsZrF₂PO₄ · H₂O, CsZr₂F₆PO₄ · 4H₂O (for the first time), CsHZrF₃PO₄ (for the first time), Cs_0.70ZrF(PO₄)_1.23 · nH₂O, and CsHZr₂F₂(P_O4)_2.66 · nH₂O. The compositions of CsZrF₂PO₄ · H₂O, Cs_0.70ZrF(PO₄)_1.23 · nH₂O, and CsHZr₂F₂(PO₄)_2.66 · nH₂O are conditional. All the compounds were characterized by crystal-optical, X-ray powder diffraction, thermal analyses, and IR spectroscopy. The formula CsHZrF₃PO₄ was established by energy-dispersive analysis with a LEO-1450 scanning electron microscope and an MS-46 CAMECA X-ray microanalyzer.     

Etude de la deshydratation de Ca(H2PO4)2·H2O et de sa reaction avec CaSO4 par ATD-ATG couplees

The dehydration of Ca(H₂PO₄)₂·H₂O was examined with simultaneous DTA and TG. This dehydration permitted clearly the apparation of the following phases: Ca(H₂PO₄)₂·0.5H₂O, Ca(H₂PO₄)₂, Ca₃(HP₂O₇)₂, Ca₂HP₃O₁₀ et Ca(PO₃)₂. The reaction of Ca(H₂PO₄)₂·H₂O and CaSO₄ was also examined with the same technics. It was found that the decomposition of CaSO₄ takes place for relatively low temperature (between 600°C and 800°C).     

Non-isothermal kinetics of thermal decomposition of NH<Subscript>4</Subscript>ZrH(PO<Subscript>4</Subscript>)<Subscript>2</Subscript>·H<Subscript>2</Subscript>O

Nanocrystalline NH₄ZrH(PO₄)₂·H₂O was synthesized by solid-state reaction at low heat using ZrOCl₂·8H₂O and (NH₄)₂HPO₄ as raw materials. X-ray powder diffraction analysis showed that NH₄ZrH(PO₄)₂·H₂O was a layered compound with an interlayer distance of 1.148 nm. The thermal decomposition of NH₄ZrH(PO₄)₂·H₂O experienced four steps, which involves the dehydration of the crystal water molecule, deamination, intramolecular dehydration of the protonated phosphate groups, and the formation of orthorhombic ZrP₂O₇. In the DTA curve, the three endothermic peaks and an exothermic peak, respectively, corresponding to the first three steps' mass losses of NH₄ZrH(PO₄)₂·H₂O and crystallization of ZrP₂O₇ were observed. Based on Flynn–Wall–Ozawa equation and Kissinger equation, the average values of the activation energies associated with the NH₄ZrH(PO₄)₂·H₂O thermal decomposition and crystallization of ZrP₂O₇ were determined to be 56.720 ± 13.1, 106.55 ± 6.28, 129.25 ± 4.32, and 521.90 kJ mol⁻¹, respectively. Dehydration of the crystal water of NH₄ZrH(PO₄)₂·H₂O could be due to multi-step reaction mechanisms: deamination of NH₄ZrH(PO₄)₂ and intramolecular dehydration of the protonated phosphate groups from Zr(HPO₄)₂ are simple reaction mechanisms.     

Transesterification of glyceryl tributyrate with methanol using strontium borate as the solid base catalyst

Four kinds of strontium borates were prepared and characterized by XRD, SEM, EDS, TG-DTA and Hammett titration method, and their catalytic activities were examined in the transesterification of glyceryl tributyrate with methanol for the first time. The separate effects of the molar ratio of methanol to oil, the reaction time, and reusability were investigated. In addition, the catalytic activities of Sr(OH)₂ and SrCO₃ were also examined for the comparison. The results showed that the basicity and catalytic activity of these catalysts were decreased as the following order: Sr(OH)₂ > SrB₂O₄·4H₂O > SrB₆O₁₀·5H₂O > SrB₂O₄ > SrB₆O₁₀ > SrCO₃, and the reusability decreases as the following order: anhydrous strontium borates (SrB₂O₄, SrB₆O₁₀) > hydrated strontium borates (SrB₂O₄·4H₂O, SrB₆O₁₀·5H₂O) > Sr(OH)₂. The results indicate that the SrB₂O₄·4H₂O with regular morphology, which was obtained at low temperature by a simple preparation method, might be as one kind of good potential alkaline earth salts catalyst for transesterification. Moreover, the possible reaction mechanism is proposed and analyzed.     

Phase formation in the HfO(NO3)2-H3PO4-CsF(HF)-H2O system

The phase formation in the system HfO(NO₃)₂-H₃PO₄-CsF(HF)-H₂O was studied along the sections at the molar ratios PO ₄ ^3? /Hf = 0.5, 1.5, and 2.0 and RbF:Hf = 1?C5, and also in the presence of HF at CsF: Hf = 1. The initial solutions contained 2?C24 wt % HfO₂. The synthesis was performed at room temperature. The following substances were isolated: crystalline cesium fluorophosphate hafnates CsHf₂F₆PO₄ · 4H₂O, CsHfF₂PO₄ · 0.5H₂O, and CsH₂Hf₂F₂(PO₄)₃ · 2H₂O; X-ray amorphous cesium fluorophosphate hafnate of the average composition Cs₂Hf₃O_1.5F₅(PO₄)₂ · 5H₂O; and X-ray amorphous cesium fluorophosphate nitrate hafnate Cs₅H₄Hf₃F₇(PO₄)_3.66(NO₃)₃ · 5H₂O. The compositions of the amorphous phases should be refined. Cesium fluorophosphate hafnates were obtained for the first time. The compounds were studied by crystal-optical, elemental, X-ray diffraction, IR spectroscopic, and electron microscopic analyses.     

Phase formation in the systems TiOCl2-H3PO4-MF(HF)-H2O (M = K, Rb, Cs)

From solutions containing 2–17 wt % TiO₂ at the molar ratios M/Ti = 1–4, F/Ti = 2–4, and PO ₄ ^3? /Ti = 0.5–10 under mild conditions, fluoro- and oxo(hydroxo) fluorophosphate titanates were isolated: crystalline M₂TiF₆ (M = K, Rb, Cs) and K₂Ti₂O_2.5F₂PO₄ · 2H₂O, and amorphous K₃Ti₄O(OH)F₇(PO₄)₃ · 5H₂O, Cs₂Ti₃O₂F₇PO₄ · 6H₂O, and CsTi₃O₃F₄PO₄ · 3H₂O. In a mixture with M₂TiF₆ and KCl, phosphate-ion-containing crystalline phases of unidentified composition were detected. The phases were studied by elemental, crystal-optical, X-ray powder diffraction, thermal, IR spectroscopic, and electron microscopic analyses. Annealing fluorophosphate titanates gives a mixture of MTiOPO₄ and TiO₂. All the mentioned alkali metal fluorophosphates contain the tetrahedral ion PO ₄ ^3? and titanium polyhedra with bonds Ti-F and Ti-O; some of them also contain bridging oxygen connecting titanium atoms: Ti-O-Ti; i.e., these substances are polymeric.     

Thermal stability and X-ray luminescent properties of cesium fluorophosphatozirconates

Crystalline cesium fluorophosphatozirconates (CFPZs) CsZr₂F₆PO₄ · 4H₂O, CsZrF₂PO₄ · 0.5H₂O, CsH₂Zr₂F₂(PO₄)₃ · 2H₂O, and amorphous Cs₂Zr₃OF₆(PO₄)₂ · 3H₂O were synthesized, and their thermal stability and luminescence ability were studied. The compositions of initial CsH₂Zr₂F₂(PO₄)₃ · 2H₂O and Cs₂Zr₃OF₆(PO₄)₂ · 3H₂O were refined. CsZr₂O_0.5F₅PO₄, CsHZr₂F(PO₄)₃, CsZr₂(PO₄)₃, and Cs₂Zr₃OF₆(PO₄)₂ crystalline intermediates, which are comparable with BaSO₄ and CaF₂ luminophors in the context of their X-ray luminescence intensity, were recognized by thermal analysis and X-ray powder diffraction under heating.     

Phase formation in the ZrO(NO3)2-NaF(HF)-H3PO4-H2O system at 20°C

Phase formation in the ZrO(NO₃)₂-NaF(HF)-H₃PO₄-H₂O system was studied at 20°C and 2.0–14.5 wt % ZrO₂ in the initial solution along sections with molar ratios PO ₄ ^3? /Zr = 0.5 and 1.5 and also in the presence of hydrogen fluoride at Na/Zr = 1 and PO ₄ ^3? /Zr = 0.5, 1.0, and 1.5. Crystalline zirconium hydrophosphate Zr(HPO₄)₂ · H₂O, fluorozirconates Na₅Zr₂F₁₃ and Na₇Zr₆F₃₁ · 12H₂O, fluorophosphatozirconates NaH₂Zr₃F₃(PO₄)₄ · 3H₂O and NaZr₂F₆(PO₄) · 4H₂O, and amorphous NaZrO_0.5F(PO₄) · 4H₂O (provisional composition) were separated at room temperature. NaH₂Zr₃F₃(PO₄)₄ · 3H₂O and NaZr₂F₆(PO₄) · 4H₂O were prepared for the first time and were studied by crystal-optical, elemental, and thermal analyses, X-ray powder diffraction, IR spectroscopy, scanning electron microscopy (SEM), and X-ray microanalysis. Na₇Hf₆F₃₁ · 12H₂O was found to exist in a mixture with the hydrophosphate.     

A first Mn member in the struvite morphotropic series,CsMn(H2O)6(PO4): hydrothermal synthesis,crystal structure and interconnections within the family of related phosphates

Caesium manganese hexahydrate phosphate, CsMn(H₂O)₆(PO₄), was synthesized under hydrothermal conditions. Its crystal structure was determined from single‐crystal X‐ray diffraction data. The novel phase crystallizes in the hexagonal space group P6₃mc and represents the first manganese member in the struvite morphotropic series, AM(H₂O)₆(TO₄). Its crystal structure is built from Mn(H₂O)₆ octahedra and PO₄ tetrahedra linked into a framework via hydrogen bonding. The large Cs atoms are encapsulated in the framework cuboctahedral cavities. It is shown that the size of the A⁺ ionic radius within the morphotropic series AM(H₂O)₆(XO₄) results is certain types of crystal structures and affects the values of the unit‐cell parameters. Structural relationships with Na(H₂O)Mg(H₂O)₆(PO₄) and the mineral hazenite, KNa(H₂O)₂Mg₂(H₂O)₁₂(PO₄)₂, are discussed.     

Thermal stability and X-ray luminescence properties of cesium fluorophosphatohafnates

The thermal stability of cesium fluorophosphatohafnates (crystalline CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O, CsHfF₂PO₄ · 0.5H₂O, CsHf₂F₆PO₄ · 4H₂O and X-ray amorphous Cs₂Hf₃O_1.5F₅(PO₄)₂ · 5H₂O, Cs₅H₄Hf₃F₇(PO₄)_3.66(NO₃)₃ · 5H₂O) was determined. The weight ratios Cs⁺/Hf and PO ₄ ^3? /ZrHf in CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O were confirmed by identifying the calcination production CsHf₂(PO₄)₃ (～1000°C). A new crystalline compound CsHf₂F(HPO₄)(PO₄)₂ was found by thermogravimetric and X-ray powder diffraction analysis during heating. A new method for hydrothermal synthesis of CsHf₂(PO₄)₃, which was different from the already known one, was proposed. It was ascertained that CsHf₂(PO₄)₃ possesses a significant X-ray luminescence; whereas in fluorophosphatehafnates show low luminescence intensity.     

Über kristalline Natriumhydroxogallate

About Crystalline Sodium Hydroxogallates Two crystalline sodium hydroxogallates 4,5 Na₂O · Ga₂O₃ · 13,5 H₂O ( I ) and 5 Na₂O · Ga₂O₃ · 8 H₂O ( II ), as well as a crystalline phase of the composition Na₂O · Ga₂O₃ · 4 H₂O · 2 NaCl ( III ) are described.     

Untersuchung der Mn(II)-phosphite mit besonderer Berücksichtigung der Wasserstoffbindungen

Manganese(II) phosphites MnHPO₃·3.6 H₂O, Mn₃H₆P₄O₁₂·1.5 H₂O, MnH₄P₂O₆·H₂O, Mn₂H₁₁P₅O₁₅·4 H₂O, Mn₂H₁₇P₇O₂₁· 4 H₂O and MnH₁₀P₄O₁₂·H₂O have been studied by IR spectroscopy, thermography and magnetic measurements. Based on the results obtained, the following structural model is proposed: in the compounds studied, each Mn(II) ion is surrounded octahedrally by the oxygen atoms of water molecules and phosphite or polyorthophosphite anions. In the phosphite MnHPO₃·3.6H₂O the C_3v symmetry of the anion decreases to C_s. The anion is characterized by the bond lengthsr _PO=1.49 Å and \(r_{PO_2 }\) =1.52 Å, force constantsK _PO=7.8 mdyn/Å and \(K_{PO_2 }\) =6.4 mdyn/Å and bond ordersN _PO=1.68 and \(N_{PO_2 }\) =2.03. Apart from the interaction between this deformed anion and the Mn(II) cation, hydrogen bonds of approximate length 2.84 Å and energy 5.0 kcal/mole are formed in the phosphite mentioned, linking the water molecules in the coordination sphere. In the other phosphites studied, the following types of hydrogen bond are found: hydrogen bonds linking hydrate water molecules, those between water molecules and the anion, and another systems of hydrogen bonds in the polyorthosphite anions.     

TG and EGA investigations of the decomposition of some metal ammonium phosphate monohydrates by means of the Derivatograph under conventional and quasi-isothermal — Quasi-isobaric conditions

The thermal decomposition of MgNH₄PO₄·H₂O, MnNH₄PO₄ · H₂O, CoNH₄PO₄ · · H₂O and CdNH₄PO₄·H₂O were investigated under conventional and under quasiisothermal-quasi-isobaric conditions. The experiments were carried out with a Derivatograph suitable for performing simultaneous TG and EGA examinations. It was found that the thermal decompositions of the four compounds each consist of two partial processes: the departure of the water of crystallization, and the subsequent inseparable escape of the ammonia and constitution water. Depending on the experimental conditions, the two processes more or less overlap. The relatively best separation of the two processes can be attained by using quasi-isothermal and quasi-isobaric conditions.     

A simple synthesis and room temperature magnetic properties of new binary Mn0.5Fe0.5(H2PO4)2·xH2O obtained from a rapid co-precipitation at ambient temperature

A new binary Mn_0.5Fe_0.5(H₂PO₄)₂·xH₂O powder was synthesized by simple and cost-effective method using phosphoric acid, manganese and iron metals as starting chemicals. The synthesized solid shows the complex thermal transformations and the final decomposition product is a new binary manganese iron cyclo-tetraphosphate, MnFeP₄O₁₂. The X-ray diffraction and FTIR results indicate that the synthesized new binary Mn_0.5Fe_0.5(H₂PO₄)₂·xH₂O and the decomposition MnFeP₄O₁₂ powders are a pure monoclinic phase with space group P2₁/n (Z = 2) and C2/c (Z = 4), respectively. The particle morphologies of Mn_0.5Fe_0.5(H₂PO₄)₂·xH₂O and MnFeP₄O₁₂ powders appear as the rod-like tetragonal shape and show a high agglomeration of small particles, which are similar to the case of Mn(H₂PO₄)₂·2H₂O and Fe₂P₄O₁₂, respectively. Room temperature magnetization results show a ferromagnetic behavior of the Mn_0.5Fe_0.5(H₂PO₄)₂·xH₂O and MnFeP₄O₁₂ powders, having the hysteresis loops in the range of ?10,000 Oe < H < +10,000 Oe with the specific magnetization values of 25.63 and 13.14 emu/g at 10 kOe, respectively. The lower magnetizations of Mn_0.5Fe_0.5(H₂PO₄)₂·xH₂O and MnFeP₄O₁₂ than those of Fe(H₂PO₄)₂·2H₂O and Fe₂P₄O₁₂ powders indicate the presence of Mn ions in substitution position of Fe ions.