Oxide layers with titanium and zirconium phosphates

Oxide-phosphate layers 20 to 150 μm thick were obtained on titanium by plasma electrolytic deposition in individual and mixed aqueous electrolytes with polyphosphate complexes of zirconium(IV), barium(II), and copper(II). Formation features, thickness, elemental and phase compositions, and surface morphology of the films are presented. Depending on the electrolyte composition, synthesis conditions, and temperature of annealing in air, some simple and double phosphates of titanium and zirconium are formed, including ZrP₂O₇, NaTi₂(PO₄)₃, BaTi₂(P₂O₇)₂, Zr_0.2Ti_0.8P₂O₇, and CuTi₂(PO₄)₃.     

Preparation and exfoliation of layered titanium butyl phosphates

Titanium butyl phosphates (TiBP) synthesized by reacting Ti(SO₄)₂ with a mixture of mono-(C₄H₉PO₄H₂) and dibutyl phosphates ((C₄H₉)₂PO₄H) in aqueous ethanol solution at 25 °C were characterized by various conventional techniques. XRD pattern of TiBP possessed a peak at 2θ?=?5.5° and a broad hump at 2θ?=?15–30°. This fact indicated that the material was composed of a multilayer alternating bilayer of butyl groups of the phosphates and amorphous titanium phosphate phase. The TiBP was spherical particles with a size of ca. 100 nm and the chemical formula of this material was Ti((C₄H₉O)₂PO₂)_x(C₄H₉OPO₃)_y(OH)_z. The TiBP possessed a UV absorption property due to charge transfer of O^2? ? Ti⁴⁺. The layered structure of TiBP was exfoliated in ethanol at 25 °C up to TiBP concentration of 1.0?×?10⁵ ppm to form nanosheet. The nanosheet dispersing solution exhibited a UV absorption property and the property depends on nanosheet concentration.     

Synthesis and ion-exchange properties of crystalline titanium and zirconium phosphates

The preparation of novel types of inorganic ion-exchangers, titanium and zirconium phosphates and their ion-exchange properties towards strontium ions, are reported and discussed. Ti(HPO₄)₂·2H₂O is shown to be very stable to hydrolysis and to have high exchange capacity in strongly acid medium. In the case of zirconium phosphate, the titration curves with alkaline earth metal hydroxides are strongly affected by hydrolysis of the exchanger and precipitation of insoluble phosphate. The degree of conversion of the exchanger at which phosphate precipitation begins was found to be 80% for Sr²⁺. The comparison of Ti(HPO₄)₂·2H₂O with the corresponding zirconium phosphate dihydrated phase suggests that the former possesses a lattice structure different from that reported for the monohydrated exchanger.This revised version was published online in November 2005 with corrections to the Cover Date.     

State of phosphorus in sorbents based on titanium and zirconium phosphates from 31P NMR spectroscopy data

A ³¹P NMR method has been used to study sorbents based on titanium and zirconium phosphates synthesized by bulk mixing the reagents and treatment of x-ray amorphous TiO₂, rutile and ZrO₂ by phosphoric acid. In the bulk titanium and zirconium phosphates the phosphorus occurs in four different states, phosphate groups bonded through cross-linking oxygen atoms with one, two, and three atoms of the metal and molecules of phosphoric acid trapped in the matrix of the sorbent in the synthesis process. It is established that the method of grafting the phosphate groups to the surfaces of the hydrated TiO₂ and ZrO₂ is determined by the crystalline and chemical properties of the surfaces.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 5, pp. 633–636, September–October, 1988.     

A new method of immobilizing ionic liquids into layered zirconium phosphates

In this work, a new method of a series of ion liquids (ILs) 1-alkyl-3-methylimidazolium chloride [Cnmim]Cl (n = 2, 4, 6, 8) intercalation into layered zirconium phosphates was investigated. It was found that theα-ZrP-2BA (i.e. pre-intercalated BA was arranged in a bilayer mode in the galleries ofα-ZrP) was a suitable host for intercalation ILs: ILs was inserted through exchanging pre-intercalated BA. And the intercalation orientation was investigated by use of X-ray diffraction (XRD) experiments and molecular modeling calculation.     

New titanium and nickel gallophosphates with layered structures

Two new transition-metal gallophosphates, (H(2)C(4)H(10)N(2))(3)[(Ti(2.5)(H(2)O)(4)Ga(5.5)(PO(4))(10)].2H(2)O (TGP-1) and [H(3.5)(C(4)H(13)N(3))(2)][(Ni(0.5)(OH)(4)Ga(5.5)(PO(4))(3)(HPO(4))(4)].2H(2)O (NGP-1), have been synthesized under mild hydrothermal conditions and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, electron paramagnetic resonance, electron probe microanalysis, and magnetic susceptibility data. TGP-1 exhibits a unique two-dimensional structure consisting of tetrahedral and octahedral metals centers and is the foremost paramagnetic TiGaPO material ever prepared. NGP-1 as well represents the first NiGaPO compound and adopts a layer structure that is constructed from hexameric M-O clusters of trigonal bipyramids and octahedra. In both compounds, the transition metals incorporate with gallium into octahedral sites only, while the four- and five-coordinated metals centers are only Ga(3+) ions. The unique sites for Ti(3+) and Ni(2+) ions have been initially elucidated from single-crystal structure refinements and further confirmed by bond-valence-sum calculations, EPR, and magnetic susceptibility studies. Crystal data: TGP-1, monoclinic, P2(1)/c; a = 25.692(2) A, b = 9.6552(8) A, c = 9.8418(8) A, beta = 96.737(2)(o) , V = 2424.5(3) A(3), and Z = 2; NGP-1, monoclinic, C2/c, a = 20.8363(12) A, b = 11.9546(7) A, c = 16.4577(9) A, beta = 117.285(1)(o) , V = 3643.3(1) A(3), Z = 4.     

Modification and intercalation of layered zirconium phosphates: a solid‐state NMR monitoring

Several layered zirconium phosphates treated with Zr(IV) ions, modified by monomethoxy‐polyethyleneglycol‐monophosphate and intercalated with doxorubicin hydrochloride have been studied by solid‐state MAS NMR techniques. The organic components of the phosphates have been characterized by the ¹³C{¹H} CP MAS NMR spectra compared with those of initial compounds. The multinuclear NMR monitoring has provided to establish structure and covalent attachment of organic/inorganic moieties to the surface and interlayer spaces of the phosphates. The MAS NMR experiments including kinetics of proton‐phosphorus cross polarization have resulted in an unusual structure of zirconium phosphate 6 combining decoration of the phosphate surface by polymer units and their partial intercalation into the interlayer space. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of sodium zirconium phosphates

Zr(O₃PONa)₂ · nH₂O can be prepared as a single crystalline phase by direct precipitation in the presence of HF. This material is a powder. When a single crystal of -HZrP is exchanged with Na⁺, Zr(O₃PONa)₂ · nH₂O is obtained as a powder-like crystal. The zero level Weisenberg photograph shows a monoclinic symmetry; the unit cell (a = 0.900 nm, b = 1.059 nm, c = 2.210 nm and β = 117.12°) contains eight formula units Zr(O₃PONa)₂ · 3H₂O. This is doubled with respect to -HZrP.     

Intercalation of melamine into layered zirconium phosphates and their adsorption properties of formaldehyde in gas and solution phase

The intercalations of melamine into α- and γ-zirconium phosphates (α- and γ-ZrP) were investigated. Melamine-intercalated α-ZrP afforded two phases with different interlayer distances (d = 1.30 and 1.55 nm). The phase with d = 1.30 nm was obtained as the mixture with original α-ZrP at 30 min reaction by batch method, whereas the single phase with d = 1.55 nm was obtained by decantation method in saturated melamine aqueous solution. Contrary to this, for γ-ZrP a phase with d = 1.78 nm was obtained by both batch and decantation methods in saturated melamine aqueous solution. And new phase with d = 1.48 nm was formed in batch method at low pH or lower concentration of melamine aqueous solution. In these phases the arrangement of melamine changed from a monolayer structure to a bilayer structure with the increase of interlayer distance. Furthermore, melamine-intercalated α- and γ-ZrP adsorbed formaldehyde gas and formaldehyde in formalin solution by interacting with melamine molecule in the interlayer region. In melamine-intercalated γ-ZrP with d = 1.48 nm, the expansion of interlayer distance to around 1.6 nm was observed after the adsorption of formaldehyde gas and formaldehyde in formalin solution. The adsorption of formaldehyde in formalin solution was accompanied with the release of melamine in the interlayer region with increasing the concentration of formaldehyde at 65 °C.     

Composite photocalysts based on the nanostructural titanium dioxide and zirconium phosphate

A series of composite photocatalysts based on titanium dioxide deposited on the surface of a zirconium phosphate support were synthesized under different synthesis and heat-treatment conditions. The study of the photodestruction kinetics of Rhodamine C showed that the synthesized composites possess high photocatalytic activity that is competitive with the activity of a commercial Hombikat UV100 photocatalyst. The composites based on zirconium phosphate treated with isopropanol at the precipitation stage whereupon heated at 550°C exhibit the highest photocatalytic activity after heating at 750°C. It was found that such zirconium phosphate support has the largest specific surface area (270 m²/g). After heating at 550°C, the surface becomes more stable to the subsequent heating to 750°C, which is necessary for the most complete crystallization of TiO₂ ensuring its high photocatalytic characteristics.     

Vibrational study of some alkylamine hydrochlorides

The i.r. spectra of some solid amine hydrochlorides are studied. The bands originating from strong hydrogen bonds between the physically adsorbed molecules and either the bromide of the polycrystalline KBr, the chloride, or other hydrochloride molecules are tentatively assigned and discussed.     

Distribution coefficients of lanthanide elements and some separations on layered hydrous titanium dioxide

Distribution coefficients /K_d/ of lanthanide elements on layered hydrous titanium dioxide, H₂Ti₄O₉.nH₂O /where n=1.2–1.3/, have been determined as a function of the pH of the aqueous phase. The plots of 1g K_d vs. pH gave straight lines with slopes equal to +3 except for the data for heavier lanthanides, suggesting ideal ion-exchange equilibria between tervalent cations in the aqueous phase and hydrogen ions in the hydrous oxide. Mutual separations of La–Cs and La–Ba have been achieved on a column of this material on the basis of large differences in affinities between the metal ion pairs.     

Uranium sorption on amorphous titanium and zirconium phosphates modified by Al3+ or Fe3+ ions

The sorption of uranium from aqueous solutions on titanium and zirconium phosphates in H⁺ and K⁺ forms modified by iron or aluminum ions has been investigated. The modified pattern of porosity is much better, than for none modified analogous, owing to their increased sorption capacity and kinetics of uranium absorption. The modified sorbents display selectivity towards uranium, that allows to purify solutions up to the content of uranium below the limit of its analytical definition.     

Vibrational spectra of cyclopentadienyl chlorides of titanium,zirconium and hafnium. internal rotation and thermodynamic functions

The infrared and Raman spectra of some cyclopentadienyl compounds of the transition metals, namely Ti(C₅H₅)Cl₃ and M(C₅H₅)₂Cl₂ (M = Ti, Zr and Hf), are reported and discussed. The infrared spectra of the gaseous species isolated in argon matrices at 10 K provide structural information about the single molecules. Particular attention has been paid to the low-frequency region in order to achieve more reliable assignments for the internal-rotation modes. The structural data and the fundamental frequencies derived from the spectra are employed in a calculation of the thermodynamic functions for these compounds in the ideal gas state.     

Methanol transformations on framework lithium zirconium vanadate phosphates

The catalytic activity of framework phosphates of the general formula LiZr₂(VO₄)_x(PO₄)_3–x with different degrees of phosphorus replacement (x = 0, 0.1, 0.3, 0.4, 0.6, and 0.8) was studied in methanol transformations in an inert atmosphere. It was shown that the ratio between the activity and selectivity of the catalysts in dehydration and dehydrogenation reactions is determined by their vanadium content and the process temperature.     

Double titanium and rare-earth phosphates

Phosphates Ln_1/3Ti₂(PO₄)₃ (Ln = Y, La, Ce, Pr, Eu, Gd, Ho) were synthesized by the citrate solgel (Pechini) method. Solid-phase reactions were activated using dispersion, pressing, and sintering microadditives. Synthesized samples were characterized by X-ray diffraction (Rietveld method), IR spectroscopy, electron microscopy, and microprobe analysis. The specific features of their structure formation were studied. The studied phosphates were shown to crystallize in the NaZr₂(PO₄)₃ (NZP/NASICON) structural type with space group R3. The framework of their structure is built of columns of TiO₆ and РО₄ polyhedra, and one of the two types of extraframework positions inside columns of polyhedra was occupied by Ln³⁺ cations at 2/3. The dependences of the unit cell parameters of Ln_1/3Ti₂(PO₄)₃ on the Ln³⁺ radius was observed to have a gadolinium kink.     

137Cs sorption on granular inorganic ion-exchangers based on titanium and zirconium hydroxophosphates

We have studied the sorption properties of some granular inorganic ion-exchangers synthesized by gel technology, such as titanium and zirconium hydroxophosphates (THP, ZHP), titanium and zirconium molybdophosphates and titanium and zirconium phosphate-ferrocyanides. A high selectivity of THP and ZHP modified with ferrocyanide and molybdate ions to¹³⁷Cs has been found. The possibility of applying inorganic sorbents for the purification of cesium-137 contaminated foodstuff is illustrated on the examples of fish treatment.     

Vibrational spectroscopic study on pH dependence of some diazines

The infrared and Raman spectra of several pyrazines and pyridazines were measured in a wide acidity range. Methods of measurements were elaborated for extreme acidity conditions. The approximate assignments of some spectra were determined. The spectra show bands with pH depending frequencies and intensities and give information on the solute—solvent interaction.     

Enzymatic synthesis of layered titanium phosphates at low temperature and neutral pH by cell-surface display of silicatein-alpha

We introduce a novel method of inorganic synthesis using the catalytic and structure-directing properties of the demosponge enzyme silicatein-alpha. Recombinant silicatein-alpha was displayed at the surface of Escherichia coli cells by fusion to outer membrane protein A and used to biocatalytically direct the formation of layered and amorphous titanium phosphates from a small water-soluble precursor at near-neutral pH at 16 degrees C. Synthesis of titanium phosphates, with potential applications in catalysis and separation technology, previously has required prolonged reactions with phosphoric acid at elevated temperatures. Additionally, we use library screening to isolate a 15-mer with affinity toward the silicatein active site (Kd ca. 50 nM) and introduce this new approach to demonstrate the success of our display strategy. Considering our previous findings with native silicatein filaments, we suggest that this scalable, efficient, cell-based system may have a broad utility for the synthesis of a range of structured metallophosphates and other inorganic materials.