Titanyl Ion Research Articles

Expanding the Chemistry of Salt-Inclusion Materials: Utilizing the Titanyl Ion as a Structure Directing Agent for the Targeted Synthesis of Salt-Inclusion Titanium Silicates

Salt-Inclusion Materials (SIMs) are a diverse and interesting class of materials. However, their synthesis has been largely serendipitous. The targeted synthesis of SIMs requires both synthetic and...

Preparation and characterization of TiO2 incorporated 13X molecular sieves for photocatalytic removal of acetaminophen from aqueous solutions

Although stabilizing of nano-particles on porous media is a suitable methods in harnessing the agglomeration and inactivation of nano-particles, but still release of particles to the environment remains the most serious challenges facing toward photocatalysis process. Attachment of nanoparticles through ion exchange may be a promising method to solving these defects. In this study TiO2 was incorporated into the 13X molecular sieves by addition of the titanyl ion through an ion-exchange of ammonium-titanyl-oxalate as well as the decomposition of titanyl oxalate salt, which remained on the zeolite through the impregnation and calcination process. A part of TiO2 on the zeolite was also bound through a TiOSi bond. The investigation of TiO2-HX catalytic potential showed that neutral pH and 500mg/L catalyst were the optimal conditions for acetaminophen removal (1mg/L) in the UV/TiO2-HX process. The maximum removal efficiency of 95.45%±0.8 was attained after 75min contact time. The acetaminophen degradation during the UV/TiO2-HX process was followed a pseudo first order kinetic model with rate constants (Kapp) of 0.8676h−1. Under the optimum conditions, maximum synergistic efficiency of 60.07% was acquired. The experimental data showed that the UV/TiO2-HX process is effective in acetaminophen removal from aqueous solutions.

Accessing alkali-free NASICON-type compounds through mixed oxoanion sol–gel chemistry: Hydrogen titanium phosphate sulfate, H1−xTi2(PO4)3−x(SO4)x (x=0.5–1)

We report a direct sol–gel synthesis and characterization of new proton-containing, rhombohedral NASICION-type titanium compounds with mixed phosphate and sulfate oxoanions. The synthetic conditions were established by utilizing peroxide ion as a decomposable and stabilizing ligand for titanyl ions in the presence of phosphates in a strong acidic medium. Thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), induction-coupled plasma optical emission spectroscopic (ICP-OES) elemental analysis, and Raman and 1H magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopic studies have determined the presence of sulfate and proton ions in the structure, for which the compositional range has been found to be H1−xTi2(PO4)3−x(SO4)x (x=0.5–1). The particulate products exhibit a nanocrystalline nature observed through characterization with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The N2 sorption isotherm measurements and subsequent Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) analyses confirmed the presence of the textural meso- and macropores in the materials. Future studies would determine the potential of the new compounds in various applications as battery materials, proton conductors and solid acid catalysts.

Crystallization of calcium phosphates from a model solution of synovial liquid in the presence of titanium compounds

The crystallization of calcium phosphates from a model solution of human synovial liquid with the participation of titanyl ions has been studied in this work. The possibility of precipitating calcium phosphates on titanium samples is checked. The energies of adhesion and cohesion of these substances on titanium are calculated.

Assembly of Nanoparticles in Zeolite Y for the Photocatalytic Generation of Hydrogen from Water

Synthesis of nanoparticles of TiO2, Pt, CdS, and their binary and ternary combinations were made on zeolite Y starting from molecular precursors that are ion exchanged into the zeolite. Nanoclusters of TiO2 in the anatase form were formed from titanyl ions at low loadings of Ti (1 per 2.5 supercages). CdS (hexagonal form) and metallic Pt were formed from Cd2+ and Pt(NH3)42+ ion exchanged into the zeolite. Binary clusters of TiO2−Pt and TiO2−CdS were also synthesized. Electron microscopy and elemental analysis suggests colocalization of the distinct nanoparticles. Photocatalytic H2 evolution is the strongest indicator of colocalization, since improvements in H2 evolution rates of ∼100 for Pt/TiO2-zeolite over TiO2-zeolite and ∼18 for CDS/TiO2-zeolite Y over CdS-zeolite Y were observed. These improvements exceed colloidal binary systems reported in the literature. However, improvements in the H2 evolution rate of the ternary system Pt/CdS/TiO2 was not as marked, as compared to the best colloidal ternary systems reported in the literature. A model is proposed that explains the colocalization of nanoparticles, mediated by the zeolite via a self-assembly process. This model also explains why the ternary system is not optimal; since the Pt needs to be associated only with TiO2 for best H2 evolution, and the zeolite-based assembly promotes a statistical colocalization of the three nanoparticles.

NMR and DFT study of chemical bonding of the titanyl ion in pentafluoro complexes (NH4)3TiOF5 and Rb2KTiOF5

19F NMR and DFT methods are used to study the electronic structure and chemical bonding of titanyl ions in pentafluoro titanyl complexes (NH4)3TiOF5 and Rb2KTiOF5. The experimental values of the anisotropy of 19F NMR chemical shifts (CSs) are shown to be consistent with the calculated parameters within the DFT method. At normal temperatures orientational disordering of octahedral [TiOF5]3- anions occurs, fluorine atoms steadily occupying cis- and trans-positions with respect to the O2- ion. In both complexes, trans-position is not fully occupied; the occupation ratio does not exceed ~4:0.9. When the temperature is decreased to 150 K, the value of the CS anisotropy of the fluorine atom resonance line in trans-position is found to be smaller than the dipole-dipole broadening, whereas the line from fluorine atoms in cis-positions transforms into an asymmetric broad line characterized by the triaxial anisotropy of the CS tensor. It is shown that the found anisotropy corresponds to violation of the axial symmetry of Ti—F cis bonds because of strong delocalization of the electron density of Ti—O bonds in the titanyl ion.

Standard enthalpy of formation of aqueous titanyl chloride, TiOCl 2(aq), at T = 298.15 K

Enthalpies of solution of TiCl 4(l) in aqueous perchloric acid have been measured in an isothermal calorimeter at T = 298.15 K at ionic strengths of (1.964, 3.002, and 4.062) mol · kg −1. These results were extrapolated to zero ionic strength using an extended Debye–Hückel equation, to yield the standard enthalpy of solution Δ sln H m ∘ ( T = 298.15 K ) = - ( 268.03 ± 0.45 ) kJ · mol - 1 ; from which the standard partial molar enthalpy of formation of the titanyl ion was derived: Δ f H m ∘ ( TiO 2 + , aq, T = 298.15 K ) = - ( 689.4 ± 4.3 ) kJ · mol - 1 .

Radiation Effects on Hollandite Ceramics developed for Radioactive Cesium Immobilization

ABSTRACTProgress on separating the long-lived fission products from the high level radioactive liquid waste (HLW) has led to the development of specific host matrices, notably for the immobilization of cesium. Hollandite (nominally BaAl2Ti6O16), one of the main phases constituting Synroc, receives renewed interest as specific Cs-host wasteform. The radioactive cesium isotopes consist of short-lived Cs and Cs of high activities and Cs with long lifetime, all decaying according to Cs+→Ba2++e- (β) + γ. Therefore, Cs-host forms must be both heat and (β,γ)-radiation resistant. The purpose of this study is to estimate the stability of single phase hollandite under external β and γ radiation, simulating the decay of Cs. A hollandite ceramic of simple composition (Ba1.16Al2.32Ti5.68O16) was essentially irradiated by 1 and 2.5 MeV electrons with different fluences to simulate the β particles emitted by cesium. The generation of point defects was then followed by Electron Paramagnetic Resonance (EPR). All these electron irradiations generated defects of the same nature (oxygen centers and Ti3+ ions) but in different proportions varying with electron energy and fluence. The annealing of irradiated samples lead to the disappearance of the latter defects but gave rise to two other types of defects (aggregates of light elements and titanyl ions). It is necessary to heat at relatively high temperature (T=800°C) to recover an EPR spectrum similar to that of the pristine material. The stability of hollandite phase under radioactive cesium irradiation during the waste storage is discussed.

Anodic Dissolution of Titanium in Acetonitrile to Ti(IV) Perchlorate and Subsequent Reductive Electrodeposition of Amorphous TiO2 Films

Anodization of titanium electrodes in acetonitrile or produces solutions of Ti(IV) as the titanyl ion. Subsequent reduction of the anodized solution produces films of amorphous on the electrode surface. The oxide films are characterized by cyclic voltammetry, electrochemical quartz crystal microbalance, X‐ray diffraction, and ultraviolet‐visible (UV‐vis) spectroscopy. The UV‐vis spectrum of the layer displays an absorption with optical gap (3.5 eV) characteristic of amorphous with a quantized size effect due to the nanometer size of the particles. The films are reversibly reduced in acetonitrile in a redox process at vs. to the lithium‐intercalated oxide. Heating the films at 500°C converts them into the crystalline anatase form. The films are capable of forming stable monolayers of carboxyl‐ and dicarboxylferrocenes only when amorphous and freshly prepared. © 1999 The Electrochemical Society. All rights reserved.

Method for prevention of corrosion of titanium and its alloys in sulfuric acid by inhibition with titanyl ion

Method for prevention of corrosion of titanium and its alloys in sulfuric acid by inhibition with titanyl ion

非晶質Ｃｏ‐Ｔｉ合金の電着

Amorphous Co-Ti alloys have been produced by both DC and pulse current plating from an acid sulfate bath, and their electrochemical properties in a sulfuric acid solution have been studied by means of electrochemical polarization measurements. X-ray intensities diffracted from the deposits were progressively lowered with increasing concentration of titanyl ion and faded away for DC-plated deposits containing 17.8mol% Ti. The pulse-plated Co-Ti alloys exhibited an amorphous phase with a high degree of homogeneity as well as high titanium content compared with DC-plated alloys. It is probable that the induced codeposition of amorphous Co-Ti alloys proceeds via the formation of a complex hydroxide, such as [Co⋅Tin(OH)2n+1]ad, as an adsorbed intermediate. The exchange current for catholic hydrogen evolution on the amorphous alloys was two orders of magnitude larger than that on pure cobalt deposits, whereas there were no differences in their corrosion resistance. This high activity for hydrogen evolution is ascribed to an increase in surface roughness caused by a selective dissolution of titanium from the amorphous alloy electrodes.

Hydrolysis of titanium(IV) in aqueous (Na,H)Cl solution

Hydrolysis of titanium(IV) has been studied in 2.0 mol dm–3 aqueous (Na,H)Cl solution at 25 °C by means of e.m.f. measurements of a cell containing 0.019 3–0.048 2 mol dm–3 titanium(IV). Titanium(IV), which is present in the form of titanyl ion, [TiO]2+, is partially hydrolyzed to form a polynuclear cationic complex, [(TiO)8(OH)12]4+(log β8,12=–1.68± 0.10).

Some Recent Developments in the Chemistry of Transition Metal Oxocations

AbstractThe range of stability of transition metal oxocations in aqueous solution is discussed. Species with a metal‐oxygen bond of order higher than unity are particularly interesting. Bond orders can sometimes be determined from bond lengths and angles, but generally only by infrared spectroscopy. – The frequency range of the metal‐oxygen stretching vibration, previously assumed as about 900–1100 cm−1, must according to these investigations be extended at least to 780 cm−1 if all multiple bonds, particularly those in trans‐dioxo complexes, are to be included. Broad bands down to 650 cm−1 are ascribed to metal‐oxygen bridges. — The existence of cations such as ZrO2+ and VO, or of the “well‐known” titanyl ion, TiO2+, has never been proved. In many cases polynuclear, oxygen‐bridged oxometal species must be assumed.

Determination of organic peracids and hydrogen peroxide in mixtures

A simple method for the determination of organic peracids and hydrogen peroxide in mixtures is presented. The method is based on the instantaneous reaction of peracids with neutral potassium iodide and on the formation of a stable complex between hydrogen peroxide and titanyl ions. This complex is decomposed with sodium fluoride and the ensuing reaction with iodide is accelerated with molybdic acid. The influence of the different additives on the analytical results has been studied.