Synthesis and sorption properties of new synthesized rare-earth-doped sodium titanate

A series of rare-earth-doped sodium titanates with the chemical formula R _x H _y Na_{4 − (x+y)}TiO₄·nH₂O (where R = Ce³⁺, Nd³⁺ and Sm³⁺) were grown employing solid-state fusion reaction technique. The physico-chemical investigations indicated that the new materials were self engineered into large particles enough to be used in sorption process and having crystalline structures containing localized Na⁺ ions. Equilibrium studies revealed that an enhancement in sorption efficiency of sodium titanate after rare-earth doping. The neodymium-rich sodium titanate exhibited a better exchange affinity for Cs⁺ compared to the other studied series. Data on the kinetics of cesium exchange fit well to pseudo-second order and intra-particle diffusion models. In a separate experiment, it was reported that the R-HNaTi series showed responsible sorption affinity toward Ce, Nd and Sm ions in their solution mixture with insignificant selectivity trend which reflects the high stability of titanate matrices.     

Hydrothermal synthesis of one-dimensional (1D) Na<Subscript>x</Subscript>TiO<Subscript>2</Subscript> nanostructures

Nanorods of sodium titanium dioxide bronze Na_xTiO₂ were synthesized by the hydrothermal treatment of the amorphous TiO₂·nH₂O gel with 10 M NaOH followed by ultrasonication in 0.1 M HCl and thermal treatment (500°C, 10 h). The thermal treatment of the nanorods does not change the morphology of the particles. According to the electron diffraction data, the Na_xTiO₂ nanorods grow along the c axis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 71–73, January, 2005.     

Koordinationsverbindungen von organischen Oxosubstanzen, 26. Mitt.: Präparation und Eigenschaften der Aluminium-Weinsäure-verbindungen

Zusammenfassung Systematisch wurden, teils durch Eindampfen von Lösungen, teils durch fraktionierte Ausfällung mittels Alkanolen, Stoffe mit verschiedenen molaren Verhältnissen an Aluminium-, Tartratund kompensierenden Natrium- bzw. Sulfationen hergestellt. Das Verhalten bei der Herstellung, die chemischen Eigenschaften, die Röntgendiagramme, die Gewichts- und Differentialthermoanalyse¹⁷ sowie die Infrarot-Spektroskopie²³ zeigten, daß folgende Stoffe als chemische Individuen anzusehen sind (T ^4- ist das vierbasische Anion der Weinsäure C₄H₂O ^4–):Al₂H₂ T(SO₄)₂·6 H₂O, Al₂HT(SO₄)_1,5·6 H₂O, Al₂ TSO₄·6 H₂O, Al₄ T ₃·12 H₂O, NaAlT·3 H₂O, AlH₃ TSO₄·3 H₂O, AlH₂ T(SO₄)_0,5·3 H₂O, AlHT·3 H₂O, Na₂AlTOH·2 H₂O, Na₃AlT(OH)₂·2 H₂O, NaAlH₄ T ₂·3 H₂O, Na₂AlH₃ T ₂·4 H₂O, Na₃AlH₂ T ₂·4 H₂O, Na₄AlHT ₂·5 H₂O, Na₅AlT ₂·4 H₂O.

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A systematic preparation of compounds, containing varying molar ratios of aluminum, sodium, tartrate and sulfate was undertaken. The compounds were precipitated either by concentrating the corresponding solutions, or by fractional precipitation with alcohols. The chemical identity of the 15 compounds was confirmed by their chemical properties, X-ray diffraction, gravimetric analysis, and differential thermoanalysis as well as I.R. spectroscopy.

     

Synthesis and sorption behavior of semicrystalline sodium titanate as a new cation exchanger

A new form of semicrystalline sodium titanate was synthesized at high temperature (1100-1150 °C) by a reaction of TiO₂ with Na₂CO₃ in an equimolar ratio. The obtained product was characterized using IR, DTA-TG, X-ray diffraction and elemental analyses. According to X-ray patterns, H₂Ti₅O₁₁ ^. nH₂O with monoclinic structure has been formed on dehydration of semicrystalline sodium titanate. Kinetic studies of the order and activation energy of a new phase transformation have been determined from DTA-thermograms. The ion exchange behavior of semicrystalline sodium titanate was studied at different g-doses as well as at different drying temperatures. The laboratory-scale ion exchange capacity, distribution studies and exchange performance for some radionuclides of a thermally prepared material were investigated. It was found that the exchange capacity was not changed after 100 kGy irradiation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Entwässerung von Kristallhydraten als Verfahren zur Reinigung von Salzen, 7. Mitt.: Über die Änderung der isomorphen Verunreinigung bei der Entwässerung von Na2SO4·10 H2O in dessen gesättigter Lösung bei der Übergangstemperatur sowie durch organische Flüssigkeiten

Zusammenfassung Es wurde die Gehaltsänderung der isomorphen Verunreinigung zweier Systeme: Na₂SO₄·10 H₂O/Na₂SeO₄·10 H₂O und Na₂SO₄·10 H₂O/Na₂CrO₄·10 H₂O während der Entwässerung sowohl in deren gesätt. Lösung bei der Übergangstemp. als auch durch Lösungsmittel (CH₃OH und C₂H₅OH) untersucht.Der nach beiden genannten Methoden durchgeführte Entwässerungsprozeß ist von einer Verminderung der isomorphen Verunreinigung begleitet. Der Reinigungskoeffizient (W) hängt mit der Beschaffenheit der isomorphen Verunreinigung und deren Konzentration im ursprünglichen Kristallhydrat zusammen. Wenn die Entwässerung unter Einwirkung organischer Lösungsmittel verläuft, istW auch noch von der Natur des Entwässerungsmittels selbst sowie von der Löslichkeit der isomorphen Verunreinigung im verwendeten Lösungsmittel abhängig.

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Dehydration of crystal hydrates as a method of purifying salts, VII: Investigation of the alteration of isomorphous contaminant content during the dehydration ofNa ₂ SO ₄·10 H₂ O in its saturated solution at the transition temperatur and by employing organic solvents

The change in the content of isomorphous contaminant of the two systems Na₂SO₄·10 H₂O/Na₂SeO₄·10 H₂O and Na₂SO₄·10 H₂O/Na₂CrO₄·10 H₂O during dehydratation has been investigated both in their saturated solution at the temperature of transition and by the solvents CH₃OH and C₂H₅OH.The dehydratation process, carried out by either method mentioned, is accompanied with a decrease of the isomorphous contaminant content in the crystalline mass. The coefficient of purification (W) depends on the nature of the isomorphous contaminant and its concentration in the initial crystallohydrate. In the case, when dehydratation takes place under the action of organic solvents,W depends also on the nature of the dehydratation agent itself, as well as on the solubility of the isomorphous contaminant in the employed solvent.

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Mit 2 Abbildungen     

Mixed insoluble acidic salts of tetravalent metals V. Effect of gamma radiation and drying temperature on granular mixed zirconium-titanium phosphates

Solid ZrOCl₂·8H₂O was added in a slow stream to a solution of phosphoric acid or to a solution of TiCl₄ in phosphoric acid to obtain granules of amorphous Zr(HPO₄)₂·nH₂O or Zr_xTi(_1–x) (HPO₄)₂·nH₂O(where x=0.95–0.80). Half of each product had been soaked in ethanol to produce alcohol solvated materials. It was found that the particle size of the resulting materials is very similar to that of ZrOCl₂·8H₂O, in such a way that it may be controlled indirectly. These materials are suitable for ion-exchange column operations. The relatively high gamma radiation doses of⁶⁰Co source did not alter its exchange properties. pH-titrations were performed by an automatic titrimeter and the exchange capacities of alkali metal ions were determined by isotopic tracer technique. Effect of drying temperature on the ion exchange properties of Na⁺, K⁺ and Cs⁺ on the granular materials have been studied. Other characterizations were made by usual chemical analysis and thermography.     

Adsorption properties of crystalline silicas: (II) Adsorption of anionic surfactants and delamination

Lamellar crystalline silicas (crystalline silicic acids, chemical composition SiO₂·xH₂O; examples: H₄Si₁₄O₃₀·xH₂O, H₄Si₂₀O₄₂·xH₂O) are distinguished from the amorphous forms by their layered structure and exceptional adsorption properties. One outstanding example is the reaction with anionic surfactants. Several types of crystalline silicas (typical H₄Si₂₀O₄₂·xH₂O) can intercalate ionic pairs consisting of surfactant anion and gegen ion into the interlayer space. The saturation value of SDS adsorption is 0.475 mmol SDS/g H₄Si₂₀O₄₂·3H₂O. The acid H₄Si₁₄O₃₀·xH₂O adsorbs anionic surfactants at the external surfaces only (saturation value 0.04 mmol/g H₄Si₁₄O₃₀·0.8 H₂O). When anionic surfactants are adsorbed in the interlayer space, the layer separation increases to such an extent that the crystals disarticulate in a fan-like manner or delaminate into thinner packets of layers or smaller aggregates. Washing-out the SDS ionic pairs or drying reconstitutes the parallel layer orientation and leads to re-aggregation of the packets and fragments.     

Aus der Chemie von Uranhexachlorid und Uranpentachloridazid

On the Chemistry of Bauxite Extraction. III. Studies in the System Na₂O? MgO? CaO? Al₂O₃? TiO₂? H₂O The formation of crystalline compounds in the system Na₂O? MgO? CaO? Al₂O₃? TiO₂? H₂O was studied at 100°C and atmospheric pressure. Magnesium titanates or magnesium aluminates were not detected in the investigated range of concentrations. In the presence of Ca(OH)₂ the same compounds are formed as in the system Na₂O? CaO? Al₂O₃? TiO₂? H₂O. In addition, sodium aluminates are formed at high sodium and aluminium concentrations.     

Lanthankomplexe mit 2,2′-Bipyridin-N,N′-dioxid

Compounds of the composition La(bpyO₂ ^*)₄Cl₃·4H₂O, La(bpyO₂)₃Cl₃·5H₂O, La(bpyO₂)₂Cl₃·3H₂O, La(bpyO₂)Cl₃·3H₂O, La(bpyO₂)₄Br₃·4H₂O, La(bpyO₂)₃Br₃·8H₂O, La(bpyO₂)₂Br₃·7H₂O, La(bpyO₂)Br₃·4H₂O, La(bpyO₂)₄I₃·3H₂O, La(bpyO₂)₃(NO₃)₃·2H₂O, La(bpyO₂)₂(NO₃)₃·2H₂O, La(bpyO₂)₄(SCN)₃·3H₂O, La(bpyO₂)₃(SCN)₃·2H₂O, La(bpyO₂)₂(SCN)₃·2H₂O were isolated. They were investigated by means of thermoanalysis, I.R. spectroscopy, X-ray diffraction and molar conductivity.     

Determination of Formation Regions of Titanium Phosphates; Determination of the Crystal Structure ofβ-Titanium Phosphate, Ti(PO4)(H2PO4), from Neutron Powder Data

The formation region of the various types of layered titanium hydrogen phosphate hydrates was investigated. The materials were prepared by hydrothermal methods, treating amorphous titanium phosphate with phosphoric acid (8 to 16M) in the temperature range 175 to 250°C. The materials obtained were:α-Ti(HPO₄)₂·H₂O,γ-Ti(PO₄)(H₂PO₄)·2H₂O, and its anhydrous formβ-Ti(PO₄)(H₂PO₄). The structure ofβ-Ti(PO₄)(H₂PO₄) has been determined by Rietveld powder refinement of high resolution neutron diffraction data. The structure is refined in the monoclinic space groupP2₁/n(No. 14). The unit cell parameters are:a=18.9503(4) Å,b=6.3127(1) Å,c=5.1391(1) Å,β=105.366(2)°;Z=4. The final agreement factors were:R_p=2.9% andR_wp=3.8%. The structure ofβ-Ti(PO₄)(H₂PO₄) is built from TiO₆octahedra linked together by tertiary phosphate (PO₄) and dihydrogen phosphate ((OH)₂PO₂) tetrahedra. The layers are held together by hydrogen bonds.     

Preparation, characterization and magnetic properties of disubstituted ternary heteropolyoxometalates [TBA]3H n [PW9MoM2-O38(H2O)2]· 3C3H6O(TBA = tetrabutylammonium, M = transition metal)

Summary The half Wells-Dawson structure complex Na₉PW₈-MoO₃₄·11H₂O has been prepared by reaction of Na₂WO₄·2H₂O, Na₂MoO₄·2H₂O and KH₂PO₄ in water. A series of transition metal substituted heteropolyoxometalate complexes with ternary Keggin structures of the general formula [TBA]₃H _n [PW₉MoM₂O₃₈ (H₂O)₂]·3C₃H₆O (TBA = tetrabutylammonium; n = 2, M = Fe³⁺; n = 4, M = Mn²⁺,Co²⁺,Cu²⁺or Zn²⁺), have been synthesized using Na₉PW₈MoO₃₄·11H₂O and the transition metal nitrate as the starting materials in aqueous solution. The compounds were characterized by elemental analyses and spectroscopy. X.p.s. data indicate that the binding energies of all the elements in the title compounds are lower than those in similar compounds. The magnetic susceptibilities of the compounds reveal antiferromagnetic properties.     

Metal complexes of the diuretic drug furosemide

New complexes of the formulaeM(fur)₂·2H₂O (M = Mn, Cu, Zn),M(fur)₂·3H₂O (M = Co, Ni, Cd), Hg₂(fur)₃Cl₂·2H₂O, Pd(fur)Cl·H₂O and Rh(fur)₃·3H₂O, wherefurH = 4-chloro-N-(2-furfuryl)-5-sulfamoylanthranilic acid, have been prepared and characterized by conductivity measurements, X-ray powder patterns, thermal methods, effective magnetic moments as well as by IR, ligand field,¹H-NMR and ESR spectroscopic studies. The anionfur ^– shows a chelated bidentate O(carboxylato), N(imino)-coordinating behaviour.

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Metallkomplexe der diuretischen Droge Furosemid

Zusammenfassung Neue Komplexe der Verbindungen:M(fur)₂·2H₂O (M = Mn, Cu, Zn),M(fur)₂·3H₂O (M = Co, Ni, Cd), Hg₂(fur)₃Cl₂·2H₂O, Pd(fur)Cl·H₂O und Rh(fur)₃·3H₂O, wobeifurH 4-chlor-N-(2-furfuryl)-5-sulfamoylanthanilsäure ist, wurden dargestellt. Die Komplexe wurden durch Leitfähigkeitsmessungen, Röntgen-Pulver-Aufnahmen, thermogravimetrische Analysen, Messungen des effektiven magnetischen Dipolemomentes sowie durch spektroskopische Untersuchungen (IR,¹H-NMR und ESR) charakterisiert. Das Anionfur ^– zeigt das Verhalten einer Chelat-bidentat-O(carboxylato),N(imino)-Koordination.

     

Vanadyl phosphate dihydrate,a solid acid: the role of water in VOPO4·2H2O and its sodium derivatives Na x (VIV x VV 1−x O)PO4·(2−x)H2O

Sodium-containing intercalates having as general formula Na _x VOPOP₄·(2–x)H₂O (0.25x<0.50) have been obtained and characterized. Orthorhombic phases, which essentially maintain the structure of the layered oxide hydrate VOPO₄·2H₂O result. Intercalated sodium ions act as pillars. The presence of H₃O⁺ ions in the parent VOPO₄·2H₂O and also in some reduced phases, is detected. The understanding of the structural role of the water molecules is advanced and the topotactic dehydration/rehydration processes are studied. The formation of a new metastable VOPO₄·H₂O phase is established.     

Protonated Sodium 1-Hydroxyethane-1,1-diphosphonates

Powder X-ray diffraction study of sodium salts of 1-hydroxyethane-1'1-diphosphonic acid (H₄L)of the compositions NaH₃L·H₂O, Na₂H₂L·4H₂O, Na₃HL·5.5H₂O showed that these compounds aresingle-phase. Some of their properties were determined. The possibility of preparing salts of other compositionswas examined.     

Capacitive and textural characteristics of manganese oxide prepared by anodic deposition: effects of manganese precursors and oxide thickness

The influence of manganese precursors on the deposition rate of hydrous manganese oxide in the amorphous form (denoted as a-MnO_x·nH₂O) and the effect of oxide thickness on the electrochemical properties of a-MnO_x·nH₂O, for application as electrochemical supercapacitors, were systematically investigated in this work. The results showed that Mn(CH₃COO)₂·4H₂O is a more promising precursor because of its high deposition rate at much lower potentials in comparison with MnSO₄·5H₂O, MnCl₂·4H₂O, and Mn(NO₃)₂·4H₂O. The capacitive characteristics of a-MnO_x·nH₂O were found to be independent of precursors, probably due to the fact that the mean oxidation state of Mn is not significantly affected by changing the anions of manganese precursors (from the XPS results). The capacity of oxide deposits was found to be proportional to the charge density of deposition (i.e., loading) of a-MnO_x·nH₂O when it was equal to or less than a critical value (ca. 3.5 C cm^–2), while poorer capacitive behavior with a lower capacity was clearly found beyond this critical value. The a-MnO_x·nH₂O deposit with 3.5 C cm^–2, exhibiting an acceptable capacitive performance, showed the highest capacity of energy storage for supercapacitors.     

R?ntgenographisches Verfahren zum Nachweis von Fluorochromaten(III) nehen Holz sowie neben Chrom(III)-arsenat

Zusammenfassung Mit Hilfe der Einzelimpulszählungsmethode am Röntgengoniometerapparat gelang es, die kristallinen Species K₂CrF₅·H₂O]·aq, (NH₄)₂[CrF₅·H₂O]·aq, die Na₃[CrF₆]-Phase und die K₂Na[CrF₆] Phase als Fixierungsprodukte wasserlöslicher Holzschutzmittel vom Typ der U-Salze sicherzustellen. Die Nachweisgrenze für K₂[CrF₅·H₂O]·aq wurde dabei neben CrAsO₄·aq zu 2,4%. neben Holzmehl zu 0,9% und im kompakten Holz zu 0,3% errechnet.

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X-ray method for detecting fluorochromates(III) in presence of wood and chromium(III) arsenate5. Communication on chromium(III) compounds as fixation products of wood preservatives

By means of the method of counting individual pulses on the X-ray goniometer device we succeeded in detecting the crystalline species K₂[CrF₅·H₂O]·aq, (NH₄)₂[CrF₅·H₂O]·aq, the Na₃[CrF₆] phase, and the K₂Na[CrF₆] phase as results of fixing of water-soluble wood preservatives of the type of U-salts. The detection limit for K₂[CrF₅·H₂O]·aq was 2.4% in presence of CrAsO₄·aq, 0.9% in presence of wood flour and 0.3% in solid wood.

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4. Mitteilung siehe [18].     

Properties of Co-Mo coatings obtained by electrodeposition at pH 6.6

Cobalt-molybdenum coatings were prepared by electrodeposition in a sulfate-citrate bath and their morphology, structure and magnetic properties were analysed. Concentrations of 0.1 mol dm^–3 CoSO₄ and 0.005 mol dm^–3 Na₂MoO₄ at pH 6.6 led to Co-Mo deposits of 20–23% Mo that can be grown to several microns over graphite or copper substrates. At low deposition potentials or current densities, the deposits presented a close-packed hexagonal structure (hcp) that evolved to a (100)+(110) preferred orientation and acicular morphology as the deposit thickness increased. When the deposition potential or the current density was made more negative, a mixed crystalline+amorphous structure was obtained. The degree of crystallinity depended on the thickness: thin films were more amorphous than the thicker ones. Co-Mo deposits showed lower saturation magnetization (M_s) and coercivity (H_c) than the pure cobalt deposits. The crystalline+amorphous films showed the lowest H_c values (around 40 Oe).     

Mixed insoluble acidic salts of tetravalent metals

Mixed amorphous, glassy type, zirconium-titanium arsenate (ZrTiAs) and hafniumtitanium arsenate (HfTiAs) have been prepared. The composition and exchange capacity of the prepared samples were investigated in comparison with pure zirconium, titanium and hafnium arsenates, respectively. For the samples the Zr_xTi_(1-x)(HAsO₄)₂·2H₂O and the Hf_xTi_(1-x)(HAsO₄)₂·2H₂O compositions (where 0<x<1) were found. The exchange capacity values were found less than those for pure arsenates, but they do not change their values under the effect of high dose of gamma-radiation.     

Dimethylammonium Trihydrogen 1-Hydroxyethane-1,1-diphosphonate

Dimethylammonium trihydrogen 1-hydroxyethane-1,1-diphosphonate (CH₃)₂NH₂(H₃L)·H₂O was prepared. Powder X-ray diffraction study showed that the polycrystalline product is single-phase. The thermal transformations of the compound were studied. The crystalline anhydrous salt was prepared by thermal dehydration of the monohydrate.     

Heat Storage Performance of Disodium Hydrogen Phosphate Dodecahydrate： Prevention of Phase Separation by Thickening and Gelling Methods

Disodium hydrogen phosphate dodecahydrate （Na2HPO4·12H2O） is an attractive candidate for phase change materials. The main problem for its practical use comes from incongruent melting character during thermal cycling. Experimentally, heat of fusion of the pure salt decreased from 200 to 25 jog 1 in a four-run freeze-thaw cycling. Additives such as thickening agent or in-situ synthesized polyacrylate sodium in the molten salt can prevent its phase separation to some extent. In the test, sodium alginate 3.0%-5.0% （w/w） thickened mixture containing Na2HPOn·12H2O and some water showed constant heat storage capacities. Polyacrylate sodium gelled salt was synthesized through polymerizing sodium acrylate in the melt of Na2HPOn·12H2O and some extra water at 50 ℃. Optimum conditions composed of sodium acrylate 3.0%-5.0% （w/w）, cross-linking agent N,N-methylenebis-acrylamide 0.10%-0.20% （w/w）, K2S208 and Na2SO3 （mass ratio 1 ; 1） 0.06%-0.12% （w/w）. As opposed to normal large crystals of pure Na2HPOn·12H2O in solid state, the gelled salt existed in a large number of tiny particles dispersed in the gel network at room temperature, commonly less than 2 mm. But only those sample particles with sizes less than 0.2 mm may have relatively stable thermal storage property. A problem encountered was the poor reproducibility of the synthesis method： heat storage capacity of the product was often very different even though the synthesis was carried out in the same conditions. An alternative gelling method by sodium alginate grafted sodium acrylate was tried and it showed a fairly good effect. Heat capacities and heat of fusion of Na2HPO4·12H2O were measured by an adiabatic calorimeter.