Titanium Salts Research Articles

The synthesis of hierarchical Zn–Ti layered double hydroxide for efficient visible-light photocatalysis

Zn–Ti layered double hydroxides (LDHs) with different Zn/Ti ratio have been synthesized by co-precipitation of zinc and titanium salts from homogeneous solution, which were demonstrated as efficient visible-light photocatalysts. Powder X-ray diffraction (PXRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM) and Brunauer–Emmett–Teller (BET) revealed that the resulting Zn–Ti LDHs possess high crystallinity, hierarchical structure as well as large specific surface area (91.96–107.9 m 2 g −1). UV–vis diffuse reflection spectroscopy (DRS) confirmed that Zn–Ti LDHs show a broad absorption in visible light region (400–700 nm). With a low band gap of ∼3.06 eV, the as-prepared Zn–Ti LDHs displayed significant photocatalytic activity for the degradation of methylene blue (MB) under visible-light irradiation (∼100% of degradation percentage in 100 min), which is much higher than that of commercial product (Degussa P25). Therefore, this work provides a detailed understanding of semiconductor properties of Zn–Ti LDHs which was unrevealed previously, and demonstrates its potential application in the field of photocatalysis.

Coagulation characteristics of titanium (Ti) salt coagulant compared with aluminum (Al) and iron (Fe) salts

In this study, the performance of titanium tetrachloride (TiCl 4) coagulation and flocculation is compared with commonly used coagulants such as aluminum sulfate (Al 2(SO 4) 3), polyaluminum chloride (PACl), iron chloride (FeCl 3), and polyferric sulfate (PFS) in terms of water quality parameters and floc properties. TiCl 4 flocculation achieved higher removal of UV 254 (98%), dissolved organic carbon (DOC) (84%) and turbidity (93%) than other conventional coagulants. Charge neutralization and physical entrapment of colloids within coagulant precipitates and adsorption, seemed to play a significant role during TiCl 4 flocculation, while the main mechanism for conventional coagulants was bridge-aggregation and adsorption. The aggregated flocs after TiCl 4 flocculation showed the fastest growth rate compared to the other coagulants, with the largest floc size (801 μm) occurring within 8 min. The floc strength factor of PACl, Al 2(SO 4) 3, PFS, FeCl 3 and TiCl 4 was 34, 30, 29, 26 and 29, respectively, while the floc recovery factor of the TiCl 4 coagulant was the lowest. Based on the results of the above study, it is concluded that the TiCl 4 flocculation can reduce the hydraulic retention time of slow and rapid mixing, however, careful handling of sludge is required due to the low recoverability of the aggregated floc.

Synthesis of TiO<sub>2</sub>/Muti-Walled Carbon Nanotubes Composite

TiO2/Multi-walled carbon nanotubes (MWNTs) were prepared via a wet chemical route with hydrolysis of titanium salts. The purification and oxidation treatment of MWNTs in concentrated HNO3 solution were conducted to modify the nanotubes. Then the pre-treated carbon nanotubes were added into the titanium salt and in the end the composites were formed. The microstructure of as-prepared TiO2/MWNTs composite was studied by TEM. The samples were calcined at different temperature. By X-ray diffraction (XRD), the phase transformation of nano-structured TiO2 in composites was determined. The photocatalytic activity of samples being calcined at different temperature was studied by using the conversion of methyl orange in aqueous solutions as probe reaction. The influence of the structure on photocatalysis efficiency was discussed. By contrast with that of pure TiO2 nanoparticles, the special structure of TiO2/MWNT composite could remarkably improve the efficiency of the photocatalytic reaction. The results indicated that the excited e- in conduction band of TiO2 might transfer into MWNTs and the possibility of the recombination of e-/h+ pairs decreased.

Mutual influence of ammonium hexafluorotitanate and hexafluorosilicate in ammonium fluoride solutions

Conditions for the hydrolysis of a titanium salt without adding alkaline reagents arise in the system (NH4)2TiF6-(NH4)2SiF6-NH4F-H2O. The hydrolysis is caused by a more alkaline pH of the (NH4)2SiF6 solution in the presence of NH4F as compared to the pH of the (NH4)2TiF6 hydrolysis beginning in a solution of NH4F of the same concentration. In the bottom phase isolated from the above system at 25°C, (NH4)2SiF6 is identified not in the cryptohalite form corresponding to the modification of the initial silicon salt, but in the bararite form. This transfer is caused by the isovalent isomorphous substitution of Si+4 ions for Ti+4 in the complex TiF62−.

Synthesis of easily shaped ordered mesoporous titanium-containing silica

A synthesis for easily shaped Ti-containing mesoporous silicates has been reported, which uses as-prepared mesoporous silica SBA-15 as a host template, an inorganic titanium salt (such as TiCl3 or TiOSO4) as a titanium source and water as a solvent. The synthesis involves three steps: obtaining as-prepared mesostructured silicate, grafting functional moieties, and thermal treatment, which is feasible in industry. The as-prepared titanium-containing mesostructured silicates can be easily shaped. XRD, N2 sorption isotherms, TEM, FT-IR and UV-vis techniques reveal that Ti-containing mesoporous silicates after calcination have the highly ordered 2-D hexagonal mesostructure, high surface areas (475–837 m2/g), large pore volumes (0.56–0.92 cm3/g), uniform pore sizes (6.4–7.3 nm), and tetrahedrally incorporated titanium species in silica frameworks. The titanium source has a great influence on grafting.

Effect of titanium on lipoprotein lipase activity in vivo and in vitro

Summary Lipoprotein lipase (LPL) is a major lipolytic enzyme in the intravascular metabolism of postprandial triglyceride-rich lipoproteins. This enzyme is synthesized and secreted by tissues and transported to the capillary endothelial surface. Decreased activity of this enzyme is suggested to be involved in arterial sequestration of lipoproteins and thus in the progression of atherosclerosis. Titanium salts are widely used in industry, medicine, and pharmacy for tablet coating, pharmaceuticals and cosmetic products. In this study the effect of titanium on post-heparin LPL activity is reported in vivo and in vitro. Methods Groups of Male Wistar rats were administered (i.p) with an acute dose of 2.5 mg/kg titanium chloride for 10 days and a chronic dose of 0.75 mg/kg for 30 and/or 60 days. Blood samples were then collected for LPL assay. For in vitro study, plasma aliquots were incubated in the presence of up to 50 mM titanium and the enzyme activity was measured. Results Animals exposed to acute dose of titanium showed about 20% reduction in LPL activity, whereas 31% and 36% reductions were observed in animals chronically exposed for 30 and/or 60 days, respectively. Titanium in vitro also led to enzyme inhibition, so that a decrease of 28–53% was seen in the presence of 0.1–50 mM titanium. This inhibition by titanium was potentiated when citrate and/or bicarbonate was present. Conclusion Although the mechanism of titanium effect on LPL activity in vivo and in vitro demands more investigations, the inhibitory effect of titanium ion in vivo should be considered seriously in subjects exposed to this metal ion. Changes in LPL activity may affect whole body lipid metabolism, a condition favorable for development and progression of atherosclerosis.

The technology of sphene concentrate treatment to obtain titanium salts

The rate of titanium (IV) extraction from sphene concentrate by its treatment with sulfuric acid solutions was determined. The sulfatization conditions to form stable titanium (IV) sulfate solutions suitable for preparing crystal substances—titanyl sulfate and ammonium titanyl sulfate—were found. The kinetics of the crystallization was studied. The phase composition of the titanium salts was established, and the content of impurities was determined by using X-ray analysis. It was shown that the technology for producing titanium salts is simple, which makes it possible to prepare in a few operations the precursors for the synthesis of hard-to-get expensive titanium-containing materials.

Isolation of niobium, tantalum, and titanium complex fluoride salts with alkali metal cations

Fluoride and oxofluoride salts of niobium, tantalum, and titanium were isolated. They precipitated from aqueous solutions and upon washing of organic extracts with aqueous solutions of ammonium, potassium, and sodium salts. The compositions of the isolated compounds were studied. Different compositions were established for the niobium salts that precipitated upon the dissolution of unwashed niobium hydroxide in hydrofluoric acid under the atmospheric pressure, in an autoclave, and upon addition of sodium, potassium, and ammonium salts to purely fluoride solutions of niobium, as well as for the tantalum ammonium and sodium salts isolated from aqueous and organic solutions. The data obtained can be used for the synthesis of niobium, tantalum, and titanium complex fluoride salts with various compositions.

Photocatalytic activities of N-doped nano-titanias and titanium nitride

TiO 2 doped with various loadings of nitrogen was prepared by nitridation of a nano-TiO 2 powder in an ammonia/argon atmosphere at a range of temperatures from 400 to 1100 °C. The nano-TiO 2 starting powder was produced in a continuous hydrothermal flow synthesis (CHFS) process involving reaction between a flow of supercritical water and an aqueous solution of a titanium salt. The structures of the resulting nanocatalysts were investigated using powder X-ray diffraction (XRD) and Raman spectroscopy. Products ranging from N-doped anatase TiO 2 to phase-pure titanium nitride (TiN) were obtained depending on post-synthesis heat-treatment temperature. The results suggest that TiN started forming when the TiO 2 was heat-treated at 800 °C, and that pure phase TiN was obtained at 1000 °C after 5 h nitridation. The amounts and nature of the Ti, O and N at the surface were determined by X-ray photoelectron spectroscopy (XPS). A shift of the band-gap to lower energy and increasing absorption in the visible light region, were observed by increasing the heat-treatment temperature from 400 to 700 °C.

Synthesis of Titanium Carbide Nano Particles by the Mechano Chemical Process

Titanium carbides are widely used for cutting tools and grinding wheels, because of their superior physical properties such as high melting temperature, high hardness, high wear resistance, good thermal conductivity and excellent thermal shock resistance. The common synthesizing method for the titanium carbide powders is carbo-thermal reduction from the mixtures of titanium oxide(<TEX>$TiO_2$</TEX>) and carbon black. The purpose of the present research is to fabricate nano TiC powders using titanium salt and titanium hydride by the mechanochemical process(MCP). The initial elements used in this experiment are liquid <TEX>$TiCl_4$</TEX>(99.9%), <TEX>$TiH_2$</TEX>(99.9%) and active carbon(<<TEX>$32{\mu}m$</TEX>, 99.9%). Mg powders were added to the <TEX>$TiCl_4$</TEX> solution in order to induce the reaction with Cl-. The weight ratios of the carbon and Mg powders were theoretically calculated. The TiC and <TEX>$MgCl_2$</TEX> powders were milled in the planetary milling jar for 10 hours. The 40 nm TiC powders were fabricated by wet milling for 4 hours from the <TEX>$TiCl_4$</TEX>+C+Mg solution, and 300 nm TiC particles were obtained by using titanium hydride.

Preparation of high-purity titanium salts from the system (NH4)2TiF6-(NH4)3FeF6-NH4F-H2O

Influence of NH4F concentration on the conditions of separation of Ti(IV) and Fe(III) salts by fractional hydrolysis under the action of ammonia in the system (NH4)2TiF6-(NH4)3FeF6-NH4F-H2O was studied. The coprecipitation of (NH4)3TiO2F5 and (NH4)3FeF6 as a result of crystallochemical substitution of Fe+3 for Ti+4 makes it possible to reduce the content of Fe(III) salts in the system. After separation of a precipitate containing up to 25% of Ti from solutions with NH4F concentrations from 10.6 to 22.3% and subsequent hydrolysis, the remaining titanium precipitates. The precipitate is annealed up to 800°C in the presence of water vapor to form TiO2 with a whiteness above 92%.

Shape-Controlled Monocrystalline Ferroelectric Barium Titanate Nanostructures: From Nanotubes and Nanowires to Ordered Nanostructures

We report for the first time on the controlled hydrothermal synthesis of barium titanate nanostructures using Na2Ti3O7 nanotubes and nanowires as synthetic precursors. A variety of nanostructured BaTiO3 have been prepared, exhibiting either simple shapes of nanowires, nanosheets, nanocubes, and hexagonal nanoparticles or ordered architectures of coral-like nanostructures of assembled nanorods, starfish-like nanostructures, and sword-like nanostructures. The shapes of the various BaTiO3 products are found to be dependent on the concentration of Ba(OH)2, the temperature, and the nature of the precursors. The synthesis route exploits the differences in the hydrothermal stability of the Na2Ti3O7 nanotubes and nanowires and the temperature-dependent crystal structure of barium titanate. Various nanoblocks, including nanosheets and nanorods formed from the Na2Ti3O7 nanotubes and nanowires, respectively, grow and assemble to form the ordered BaTiO3 nanostructures. This represents a new approach that is capable of assembling ordered perovskite nanostructures using relatively large nanoblocks formed from layered alkali-metal titanates. The process offers more flexibility than those using inorganic titanium salts or organometallic titanium compounds, which commonly leads to the formation of only BaTiO3 nanoparticles.

Coprecipitation of titanium(IV) and Iron(III) complex salts from peroxide-fluoride solutions

Because the salts (NH4)3TiO2F5 and (NH4)3FeF6 are isostructural, precipitation of the titanium peroxy salt from the (NH4)2TiF6-(NH4)3FeF6-NH4F-H2O2 system is accompanied by crystal-chemical substitution of ions. As a result of partial peroxolysis, the iron salt coprecipitates with ammonium peroxypentafluorotitanate. If the degree of precipitation is higher than 20%, TiO2 samples of high whiteness can be prepared from the hydrolysis product isolated from such solutions, after annealing at 850°C.

A Novel Hybrid Method of Sol–Gel and Ultrasonic Atomization Synthesis and Piezoelectric Properties of SrBi4Ti4O15 Ceramics

SrBi4Ti4O15(SBTi) powders were synthesized by a novel hybrid method of sol–gel and ultrasonic atomization. TiO2 particle was used as a starting material to replace other expensive soluble titanium salts. X‐ray diffraction results showed that the pure‐phase SBTi powders were obtained at 700°C for 2 h, which is much lower than the calcination temperature (800°–850°C) required in solid‐state reactions. The ceramics sintered at 1100°C for 1 h exhibited 94.5% of relative density and a piezoelectric coefficient of 21 pC/N. The results showed that this hybrid method could lead to an attractive method for the industrial fabrication of SBTi materials.

Changes in Liver Contents of Lipid Fractions Following Titanium Exposure

The potential to cause tissue damage by metal ions is the matter of widespread investigation. Titanium salts are widely used in industry for ceramic painting, in pharmacy for tablet coating and making chemical sunscreens and in medicine as photo catalysts with bactericidal activity. This may address the idea that the exposure to these salts could play a role in metabolic disorders. In this study the effect of Ti on liver contents of lipid fractions was investigated. Male Wistar rats (200-250 g) were used for the experiments. Groups of animals were injected for 10 days with 2.5 mg/kg of titanium chloride, as acute dose and for 30 and 60 days with 0.75 mg/kg as chronic doses. At the end of the experimental period animals were anaesthetized, the abdomens were opened and the livers were perfused with appropriate buffer. Livers were then removed immediately and used fresh or kept frozen until the analysis. Livers were then homogenized and their contents of triglycerides and phospholipids were determined. Blood samples were also collected before killing to measure the lipid levels. Titanium led to a significant increase in phospholipid content of the liver (about 66 %) whereas triglycerides decreased by about 25 to 30 percent in all treated animals. Titanium also reduced plasma free fatty acids and triglycerides significantly but cholesterol and LDL levels were increased in all treated animals. Lipoprotein lipase activity was also inhibited in titanium treated animals. In Conclusion This study is significant because it shows that chronic inhalation or exposure to titanium at workplaces is associated with changes in liver lipid metabolism. Plasma lipid-related parameters were also affected. Although less information is available concerning the mechanism of toxicity but the induction of reactive oxygen species production may be responsible for this effect.

Titanium interaction with hydroxide-salt melts

The reaction of titanium with fused mixtures based on sodium hydroxide and various salts (sodium nitrate and nitrite, sodium and potassium chlorides, sodium orthophosphate, sodium meta-and orthotitanates, potassium oxyfluoride and hexafluorotitanate) is studied. The mechanism of inhibiting the corrosion of the studied metal in ionic melts that involve oxidants and titanium salts is discussed.

Synthesis and Characterization of Novel Titanium, Germanium, and Tin Silazane Complexes Bearing a Cyclohexasilazanetriido Ligand

AbstractNovel heterometallic silazane complexes were synthesized by the reaction of 1‐lithio‐2,2,4,4,6,6‐hexamethylcyclotrisilazane Li(HMCTS)H2 with the tetrachloride salts of titanium and germanium as well as by the reaction of 1,1,3,3,5,5‐hexamethylcyclotrisilazane H3(HMCTS) with tin tetrachloride and excess triethylamine. The products [H3(DMCHS)TiCl] (1), [H3(DMCHS)GeCl] (2), and [H3(DMCHS)SnCl] (3) {H3(DMCHS) = 2,2,4,4,6,6,8,8,10,10,12,12‐dodecamethylcyclohexasilazane‐1,5,9‐triido} were characterized by 1H‐, 13C‐, 14N‐, and 29Si NMR spectroscopy, elemental analyses and single‐crystal X‐ray structure analyses. The complexes have a surprising and interesting structure, that of a new dodecamethylcyclohexasilazane system with the Ti, Ge, or Sn atom in the center. These metal atoms are coordinated by one chlorine atom and three nitrogen atoms. The metal centers are part of three six‐membered hetero‐silazane rings. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)

Synthesis of Titania Thin Films by Cathodic Electrolytic Deposition

The cathodic electrodeposition of titania thin films from solutions containing a titanium salt was studied. Titanium tetrachloride was dissolved in an ethanol-water solution with hydrogen peroxide to prepare titanium peroxocomplex solutions. The deposition of the titania precursor on platinum-coated silicon wafer substrates was carried out by electrolysis of the solutions under constant current conditions. The deposits were thermally treated at fixed temperatures in air and then characterized by X-ray diffraction and scanning electron microscopy.

Hydrophilicity of titanium oxide coatings with the addition of silica

This work investigated hydrophilicity between titanium oxide coatings with and without addition of silica. A sol of titania and silica was prepared for sol–gel coating. The sol of titanium oxide is aqueous, and the mixed sol is transparent with a pH value of 8.0. Coating was prepared by spraying mixed sol over a heated substrate. The titanium oxide sol was prepared by using an inorganic titanium salt. A silica sol was then added to titanium oxide sol obtain the mixed sol. Thickness of the coatings were between 20 and 80 nm. The sols were characterized by IR spectroscopy. AFM was used to investigate the coating surface structure and roughness. The crystalline size of coating surface for the mixed oxides was little greater than for the pure titanium oxide. The crystalline phase was investigated using X-ray diffraction. The hydrophilicity of coatings was studied with UV and sunlight exposure and by measurement of contact angle change of droplets of water. Through the investigation of change of contact angle and water droplets on the surface after UV exposure and sunlight radiation, it can be concluded that hydrophilicity of mixed coatings with low temperature heat-treatment of titanium oxide and silica are much better than a pure titanium oxide coating. This effect makes for an improved self-cleaning coating.

Titanium, zinc and alkaline-earth metal complexes supported by bulky O,N,N,O-multidentate ligands: syntheses, characterisation and activity in cyclic esterpolymerisation

The reactions of the bulky amino-bis(phenol) ligand Me(2)NCH(2)CH(2)N[CH(2)-3,5-Bu(t)(2)-C(6)H(2)OH-2](2)(1-H(2)) with Zn[N(SiMe(3))(2)](2)(4), [Mg[N(SiMe(3))(2)](2)](2)(5) and Ca[N(SiMe(3))(2)](2)(THF)(2)(6) yield the complexes 1-Zn, 1-Mg and 1-Ca in good yields. The X-ray structure of 1-Ca showed the complex to be dimeric, with calcium in a distorted octahedral coordination geometry. Five of the positions are occupied by an N(2)O(3) donor set, while the sixth is taken up by an intramolecular close contact to an o-Bu(t) substituent, a rare case of a Ca...H-C agostic interaction (Ca...H distances of 2.37 and 2.41 Angstroms). Another sterically hindered calcium complex, Ca[2-Bu(t)-6-(C(6)F(5)N=CH)C(6)H(3)O](2)(THF)(2).(C(7)H(8))(2/3)(7), was prepared by reaction of 6 with the iminophenol 2-Bu(t)-6-(C(6)F(5)N=CH)C(6)H(3)OH (3-H). According to the crystal structure 7 is monomeric and octahedral, with trans THF ligands. The complex Ti[N[CH(2)-3-Bu(t)-5-Me-C(6)H(2)O-2](2)[CH(2)CH(2)NMe(2)]](OPr(i))(2)(2-Ti) was prepared by treatment of Ti(OPr(i)(4)) with the new amino-bis(phenol) Me(2)NCH(2)CH(2)N[CH(2)-3-Bu(t)-5-Me-C(6)H(2)OH-2](2)(2-H(2)). The reduction of 2-Ti with sodium amalgam gave the titanium(III) salt Ti[N[CH(2)-3-Bu(t)-5-Me-C(6)H(2)O-2](2)[CH(2)CH(2)NMe(2)]](OPr(i))(2).Na(THF)(2)(8). A comparison of the X-ray structures of 2-Ti and 8 showed that the additional electron in 8 significantly reduced the intensity of the pi-bonding from the oxygen atoms of the isopropoxide groups to titanium. 1-Ca and 8 were active initiators for the ring-opening polymerisation of epsilon-caprolactone (up to 97% conversion of 200 equivalents in 2 hours) and yielded polymers with narrow molecular weight distributions.