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Query: KEGG:D01931 (TiO2)
 11,320 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chemical separations for Ga-68 from Ge-68 using adsorption chromatography on inorganic materials are described. The adsorbents used were TiO2, ZrO2, and SiO2. Distribution coefficients for Ge and Ga on these absorbents were determined as a function of reagent concentration and duration of equilibration. The distribution coefficient (w/w) for Ge on SiO2 reached 250 in 6 N HNO3, whereas Ga was no significantly adsorbed. Therefore, Ga-68 can be collected with a mall volume of 6 N HNO3 eluent. By contrast, large volumes of 1 N HNO3 were necessary to collect Ga-68 from ZrO2, since the KD of Ga under these circumstances was about 50. The Ga-68 eluted from TiO2 was chemically contaminated with titanates and would require additional chemical manipulation in order to make it injectable. All the adsorbents could lead to chromatographic systems that would allow acceptable chemical separations. However, the specific requirements for a radionuclide generator, usable in a hospital environment, make the SiO2-based system the most attractive.
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PMID:Potential column chromatography generators for ionic Ga-68. I. Inorganic substrates. 23 43

Surgical implant finishing and sterilization procedures were investigated to determine surface characteristics of unalloyed titanium (Ti). All specimens initially were cleaned with phosphoric acid and divided into five groups for comparisons of different surface treatments (C = cleaned as above, no further treatment; CP = C and passivated in nitric acid; CPS = CP and dry-heat sterilized; CPSS = CPS and resterilized; CS = C and dry-heat sterilized). Auger (AES), X-ray photoelectron (XPS), and Raman spectroscopic methods were used to examine surface compositions. The surface oxides formed by all treatments primarily were TiO2, with some Ti2O3 and possibly TiO. Significant concentrations of carbonaceous substances also were observed. The cleaning procedure alone resulted in residual phosphorus, primarily as phosphate groups along with some hydrogen phosphates. A higher percentage of physisorbed water appeared to be associated with the phosphorus. Passivation (with HNO3) alone removed phosphorus from the surface; specimens sterilized without prior passivation showed the thickest oxide and phosphorus profiles, suggesting that passivation alters the oxide characteristics either directly by altering the oxide structure or indirectly by removing moieties that alter the oxide. Raman spectroscopy showed no crystalline order in the oxide. Carbon, oxygen, phosphorus, and nitrogen presence were found to correlate with previously determined surface energy.
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PMID:Effect of surface treatment on unalloyed titanium implants: spectroscopic analyses. 959 42

In this study, methodologies for determining titanium oxide, zinc oxide and iron oxide are proposed and assayed in commercial sunscreen products. The proposed methodology for TiO2, determination in sunscreens is based on a microwave-assisted treatment for digesting the organic components in a closed teflon reactor in presence of HNO3 and HCl. Titanium is determined by inductive coupled plasma emission spectrometry (ICP-AES). The proposed methodologies for measuring ZnO and Fe2O3 are based on a sample emulsification in water with a non ionic tensioactive and IBMK, followed by Zn and Fe determination by flame atomic absorption spectrometry (FAAS). The methodologies allow a precise and accurate determination of metallic oxides in UV sunscreen creams, where the sample treatment is less time-consuming than in the classic methods. To our knowledge this is the first study focused to the determination of metallic oxides in commercial sunscreen products.
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PMID:Analytical methodologies for atomic spectrometric determination of metallic oxides in UV sunscreen creams. 1071 13

The treatment of the simulated wastewater containing formic acid and Cu(II) ions was investigated using photocatalytic technology of immobilized TiO2 film. The technology could efficiently remove COD and Cu(II) from the solution. In parallel, a rapid deactivation for COD removal was observed in a successive batch experiment. By XRD, UV-Vis diffuse reflectance spectra, SEM image and TG analysis, it was inferred that the deactivation was attributed to the shield of the deposited Cu(0) from UV light. The Cu(0)-fouled TiO2 film could be regenerated using three kinds of methods, air oxidation, electrochemical oxidation and air-assisted electrochemical oxidation. The regeneration time was mainly dependent on the used regeneration strategy while the regeneration extent was obviously associated with the tested regeneration medium. For the deactivated film with a relative activity of about 20%, the regeneration time is in order air-assisted electrochemical oxidation < electrochemical oxidation < air oxidation, and HNO3 medium has a regeneration extent of 97.2% for the air-assisted electrochemical oxidation, more desirable than HCl and H2SO4 mediums.
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PMID:Strategies for regeneration of copper(0)-deposited TiO2 photocatalytic film. 1236 45

This study was undertaken to examine the degradation of TNT, RDX and HMX in a circular photocatalytic reactor with TiO2 as a photocatalyst. We examined the impact of parameters such as the initial concentration, initial pH of solution on rates of photocatalized transformation, and the mineralization. The results showed that photocatalysis is an effective process for the degradation of TNT, RDX and HMX. They could be comoletely degraded in 150 min with 1.0 g/L TiO2 at pH 7. An increase in the photocatalytic degradation of HMX was noticed with decreasing initial HMX. The rates of RDX and HMX degradation were greater in neutral pH than in acidic and alkaline conditions. In case of TNT degradation, the rate of degradation was the fastest at pH 11. Approximately 82% TOC decrease in the TNT degradation was achieved after 150 min, whereas TOC decrease in RDX and HMX was 24% and 59%, respectively. Nitrate, nitrite, and ammonium ions were detected as the nitrogen byproducts from the photocatalysis, and more than 50% of the total nitrogen was recovered as nitrate ion in every explosives.
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PMID:Photocatalytic degradation of explosives contaminated water. 1252 45

The biocompatibility of commercially pure titanium and its alloys is closely related to their surface properties, with both the composition of the protecting oxide film and the surface topography playing an important role. Surfaces of commercially pure titanium and of the two alloys Ti-6Al-7Nb and Ti-6Al-4V (wt %) have been investigated following three different pretreatments: polishing, nitric acid passivation and pickling in nitric acid-hydrogen fluoride. Nitric acid treatment is found to substantially reduce the concentration of surface contaminants present after polishing. The natural 4-6 nm thick oxide layer on commercially pure titanium is composed of titanium oxide in different oxidation states (TiO2, Ti2O3 and TiO), while for the alloys, aluminium and niobium or vanadium are additionally present in oxidized form (Al2O3, Nb2O5 or V-oxides). The concentrations of the alloying elements at the surface are shown to be strongly dependent on the pretreatment process. While pickling increases the surface roughness of both commercially pure titanium and the alloys, different mechanisms appear to be involved. In the case of commercially pure titanium, the dissolution rate depends on grain orientation, whereas in the case of the two alloys, selective alpha-phase dissolution and enrichment of the beta-phase appears to occur.
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PMID:Surface characterization of implant materials c.p. Ti, Ti-6Al-7Nb and Ti-6Al-4V with different pretreatments. 1534 92

The adsorption behavior of Cd, Co and Zn on nanometer-size TiQ2 was investigated. At pH 9.0, Cd, Co and Zn were retained on the nanometer-size TiO2, then eluted with 0.1 mol x L(-1) HNO3 and determined by ICP-AES. The adsorption capacities of nanometer TiO2 were found to be 8.1, 6.9 and 15.1 mg x g(-1) for Cd, Co and Zn respectively. The detection limits (3sigma) for Cd, Co and Zn are 5.1, 3.4 and 2.9 ng x mL(-1) respectively. The proposed method has been applied to the determination of trace Cd, Co and Zn in environmental samples with satisfactory results.
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PMID:[Nanometer-size titanium dioxide separation/preconcentration and ICP-AES for the determination of Cd, Co and Zn]. 1601 28

The adsorption behavior of nanometer TiO2 towards Gallium (Ga) Indium (In) and Thallium (Tl) was investigated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The optimum conditions for adsorption were studied in detail, and the test included sorption kinetics, effect of pH on adsorption ratio, enrichment factor, and adsorption capacity. Under the optimum conditions, Ga (III), In(III) and Tl(I) ions could be adsorbed and recovered quantitatively. The static adsorption capacities of Ga(III), In(III) and Tl(I) on nanometer TiO2 were 48.6, 46.6 and 23.4 mg x g(-1) respectively. For the elution of Ga(III), In (III) and Tl(I), a mixture of 0.1 mol x L(-1) EDTA solution and 1.0 mol x L(-1) HNO3 was used, and the recovery ratio was above 92%. According to the definition of IUPAC, the detection limits (3sigma) of this method for Ga, In and Tl with an enrichment factor of 12.5 are 3.0, 6.0 and 13 ng x mL(-1), respectively; and relative standard deviations (RSD) are 1.85%, 1.96% and 3.4%, respectively (n = 6). The proposed method has been applied successfully to the analysis of geological samples with satisfactory results.
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PMID:[Study on the adsorption behavior of Ga, In and Tl on nanometer-size titanium dioxide by ICP-AES]. 1624 Oct 74

A novel and effective system was developed for the complete treatment of NOx from flue gases. The system consisted of photocatalytic or ozone oxidation of NOx, followed by scrubbing and biological denitrification. Maximum photocatalytic oxidation of NOx was achieved while using powdered TiO2 at a catalytic loading rate of 10 g/h, relative humidity of 50%, and a space time of 10 s. The used catalyst was regenerated and reused. A total of 72% of oxidized NO was recovered as HNO3/HNO2 in the regeneration process. Stoichiometrically, 10% excess ozone was able to affect 100% oxidation of NO to NO2. Presence of SO2 adversely influenced the oxidation of NO by ozone. The scrubbing of NO was effective with distilled water. Heterotrophic denitrifiers were able to denitrify the leachate with an efficiency of 90%, using sewage (COD 450 mg/L) as electron donor. The new integrated treatment system seems to be a promising alternative for complete treatment of NOx from flue gases.
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PMID:Integrated system for the treatment of oxides of nitrogen from flue gases. 1650 54

Preparation of anatase TiO2 nanorods from solutions in the absence of surfactants or templates has rarely been reported. The present work has found that hydrothermal treatment of titanate nanotube suspensions under an acidic environment resulted in the formation of single-crystalline anatase nanorods with a specific crystal-elongation direction. The nanotube suspensions were prepared by treatment of TiO2 in NaOH, followed by mixing with HNO3 to different pH values. The crystal size of the anatase nanoparticles obtained from the hydrothermal treatment increased with the pH of the suspensions, and nanorods with an aspect ratio up to 6 and a long axis along the anatase [001] were obtained at a pH slightly less than 7. A mechanism for the tube-to-rod transformation has been proposed on the basis of the crystalline structures of the tubes and rods. The local shrinkage of the tube walls to form anatase crystallites and the subsequent oriented attachment of the crystallites have been suggested to be the key steps involved in the nanorod formation.
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PMID:Hydrothermal synthesis of single-crystalline anatase TiO2 nanorods with nanotubes as the precursor. 1650 14


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