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

Asbestos causes asbestosis and malignancies by mechanisms that are not fully understood. Alveolar epithelial cell (AEC) injury by iron-induced reactive oxygen species (ROS) is one important mechanism. To determine whether asbestos causes apoptosis in AECs, we exposed WI-26 (human type I-like cells), A549 (human type II-like cells), and rat alveolar type II cells to amosite asbestos and assessed apoptosis by terminal deoxynucleotidyl transferase-mediated deoxyuridine-5'-triphosphate-biotin nick end labeling (TUNEL) staining, nuclear morphology, annexin V staining, DNA nucleosome formation, and caspase 3 activation. In contrast to control medium and TiO2, amosite asbestos and H2O2 each caused AEC apoptosis. A role for iron-catalyzed ROS was suggested by the finding that asbestos-induced AEC apoptosis and caspase 3 activation were each attenuated by either an iron chelator (phytic acid and deferoxamine) or a.OH scavenger (dimethyl-thiourea, salicylate, and sodium benzoate) but not by iron-loaded phytic acid. To determine whether asbestos causes apoptosis in vivo, rats received a single intratracheal instillation of amosite (5 mg) or normal saline solution, and apoptosis in epithelial cells in the bronchoalveolar duct regions was assessed by TUNEL staining. One week after exposure, amosite asbestos caused a 3-fold increase in the percentage of apoptotic cells in the bronchoalveolar duct regions as compared with control (control, 2.1% +/- 0.35%; asbestos, 7.61% +/- 0.15%; n = 3). However, by 4 weeks the number of apoptotic cells was similar to control. We conclude that asbestos-induced pulmonary toxicity may partly be caused by apoptosis in the lung epithelium that is mediated by iron-catalyzed ROS and caspase 3 activation.
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PMID:Asbestos causes apoptosis in alveolar epithelial cells: role of iron-induced free radicals. 1132 27

Doped TiO2 samples using different preparative procedures were synthesized using either urea or thiourea leading to N- or S-doped TiO2. Photocatalytic peroxidation and oxidation (mineralization) of phosphatidylethanolamine (PE) lipid with doped TiO2 were carried out under light irradiation lambda > 410 nm. The formation of conjugated double bonds in PE molecules was followed to detect the formation of peroxy radicals (peroxidation index) under light excitation (lambda > 410 nm) when doped TiO2 was used. The kinetics of CO2 production was monitored during the mineralization of PE. Colored TiO2 powders were studied in detail by different and complementary physicochemical techniques. The band gap energies of colored TiO2 were determined by diffuse reflectance spectroscopy (DRS). The visible absorption shoulder of TiO2 was observed to follow Urbach's law. The variation of the transient decay after 354 nm laser pulse excitation does not correlate with the different N- and S-TiO2 doping levels introduced by the addition of urea or thiourea. This suggests that the states (recombination centers or traps) introduced by the doping are not effective in varying the decay kinetics within the nanosecond and microsecond time scale. Elemental analysis shows comparable amounts of S- and N-doping of TiO2 when thiourea is used as dopant. X-ray diffraction reveals no rutile in S-TiO2 samples heated to 600 degrees C, suggesting that the addition of sulfur precludes rutilization during sample crystallization. X-ray photoelectron spectroscopy (XPS) of the S-TiO2 samples confirms the preferential localization of S on the 20 topmost layers of S-TiO2 upon calcination at 500 degrees C for 2 h.
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PMID:Preparation, testing and characterization of doped TiO2 active in the peroxidation of biomolecules under visible light. 1685 54

A novel method for prevention of the oxidation of Sb(III) during sample pretreatment, preconcentration of Sb(III) and Sb(V) with nanometer size titanium dioxide (rutile) and speciation analysis of antimony, has been developed. Antimony(III) could be selectively determined by flow injection-hydride generation-atomic absorption spectrometry, coexisting with Sb(V). Trace Sb(III) and Sb(V) were all adsorbed onto 50 m g TiO2 from 500 ml solution at pH 3.0 within 15 min, then eluted by 10 ml of 5 mol/l HCl solution. One eluent was directly used for the analysis of Sb(III); to the other eluent was added 0.5 g KI and 0.2 g thiourea to reduce Sb(V) to Sb(III), then the mixture was used for the determination of total antimony. The antimony(V) content is the mathematical difference of the two concentrations. Detection limits (based on 3sigma of the blank determinations, n=11) of 0.05 ng/ml for Sb(III) and 0.06 ng/ml for Sb(V), were obtained.
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PMID:Speciation of antimony by preconcentration of Sb(III) and Sb(V) in water samples onto nanometer-size titanium dioxide and selective determination by flow injection-hydride generation-atomic absorption spectrometry. 1703 69

S-doped TiO2 photocatalyst with high visible light activity was prepared by acid catalyzed hydrolysis method using thiourea (TU) as sulfur source. The catalyst was characterized by DRS, XPS, XRD, FTIR, SEM and N2 adsorption. It was found that cation S6+ was homogeneously incorporated into the bulk phase of TiO2 and substitutes for some of the lattice titanium (Ti4+). Doped S can form a new band above the valence band and narrow the band-gap of the photocatalyst, giving rise to a second absorption edge in the visible light region. The activity of the catalyst was examined by photodegradation of phenol in aqueous solution under both artificial visible light and solar light irradiation. The activity of catalyst was found to be dependent on the doping amount of S and the maximum activity was observed when the catalyst was obtained by calcinated at 600 degrees C with the mass ratio of TU/TiO2=1. Too much of new-generated band-gap structures due to higher S-doping could act as recombination centers for electron-hole pairs. Catalyst with optimum S-doping exhibited the highest activity under both artificial light and solar irradiation for phenol degradation. In addition, doped S also beneficial for the better dispersion, large S(BET) and phase transformation retardation of TiO2.
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PMID:A visible light response TiO2 photocatalyst realized by cationic S-doping and its application for phenol degradation. 1767 65

Titanium dioxide was obtained in its pure form (TiO2) and in the presence of urea (u-TiO2) and thiourea (t-TiO2) using the sol-gel technique. The obtained powders were characterized by BET surface area analysis, Infrared Spectroscopy, Diffuse Reflectance Spectroscopy and the Rietveld refinement of XRD measurements. All the prepared catalysts show high anatase content (>99%). The a and b-cell parameters of anatase increase in the order TiO2<u-TiO2<t-TiO2, while the c-parameter presents the opposite trend. Because of the interplay in cell dimensions, the cell grows thicker and shorter when prepared in the presence of urea and thiourea, respectively. The cell volume decreases in the order t-TiO2>u-TiO2>TiO2. The photocatalytic activities of the samples were determined on flumequine under solar-simulated irradiation. The most active catalysts were u-TiO2 and t-TiO2, reaching values over 90% of flumequine degradation after 15 min irradiation, compared with values of 55% for the pure TiO2 catalyst. Changing simultaneously the catalyst amount (t-TiO2) and pH, multivariate analysis using the response surface methodology was used to determine the roughly optimal conditions for flumequine degradation. The optimized conditions found were pH below 7 and a catalyst amount of 1.6 g L(-1).
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PMID:Photocatalyzed degradation of flumequine by doped TiO2 and simulated solar light. 1816 26

A new method for the determination of trace gold by flame atomic absorption spectrometry (FAAS) after preconcentration with p-dimethylaminobenzylidenerhodanine (DMABR) loaded with nanometer TiO2 was developed. The method is convenient, highly precise and linear in a wide range. Under dynamic condition, the optimum pH of solution, flow rate, elution conditions were obtained for preconcentration of trace gold. And the effect of interfering ions was also investigated. It was found that the studied gold could be quantitatively preconcentrated on loaded nanometer TiO2 at pH = 3.5, and the flow rate of sample solution was 0.6 mL x min(-1), and the flow rate of eluting solution with 0.1 mol x L(-1) HCl-0.5 mol x L(-1) thiourea was 0.5 mL x min(-1), sufficient for complete elution. The dynamic adsorption capacity of gold on load nanometer TiO2 was 23.19 mg x g(-1). The linear range for gold was 0-0.40 microg x mL(-1), correlation coefficient was 0. 999 3, detection limit (3sigma, n = 11) for gold was 2.34 ng x mL(-1), and the relative standard deviation was 2.9% (n = 6, c = 0.10 microg x mL(-1)), the recovery was in the range of 96.7%-101.7%. The method has been applied to the determination of trace gold in water samples with satisfactory results.
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PMID:[Determination of trace gold by flame atomic absorption spectrometry after separation and preconcentration with load nanometer titanium dioxide]. 1847 46

In this study, titanium (Ti), ferric (Fe) and aluminum (Al) salt flocculants were compared for their efficiency in treating wastewater collected from Sydney Olympic Park wastewater treatment plant by following the jar test procedure. Produced sludge from Ti-salt flocculation was dried and titanium dioxide (TiO2) nanoparticles were generated after the incineration of sludge produced from the Ti-salt flocculation of wastewater. Later on, titanate nanotubes were synthesized after TiO2 nanoparticles were hydrothermally treated with 10 N NaOH solution at 130 degrees C for 24 h. Titanate nanotubes were either acid or deionised water-washed, while thiourea-doping was employed to produce visible light-responsive nanotubes. Wastewater flocculation using Ti-salt was found to be as efficient as Fe and Al flocculation in terms of turbidity and DOC removal. XRD results showed that the anatase structure was predominant for TiO2 nanoparticles, while thiourea-doped titanate nanotubes only indicated anatase structure with an increased crystallinity after being crystallized at 600 degrees C. The photocatalytic activity of all photocatalysts was evaluated using the photooxidation of acetaldehyde. Thiourea-doped nanotubes showed a greater photocatalytic activity than as-prepared TiO2 nanoparticles, deionised water-washed, acid-washed titanate nanotubes and P25 under UV and visible light irradiation.
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PMID:Preparation and characterisation of titanium dioxide (TiO2) and thiourea-doped titanate nanotubes prepared from wastewater flocculated sludge. 1963 28

Removal efficiency and influencing factors of bisphenol A by the combined process of solar irradiation and S-doped TiO2 were studied in detail, in which S-doped TiO2 photo-catalyst with high activity was prepared by acid catalyzed hydrolysis method using thiourea as sulfur source. Results showed that bisphenol A could be more effectively oxidized by the solar/S-doped TiO2 process than by solar/TiO2 process, whose removal effect were 79% and 49% after 30 min's irradiation, respectively. Pseudo-first-order model could be used to simulate the oxidation process in which the degradation rate coefficients were independent of the initial concentration of bisphenol A. Degradation rate could be greatly affected by the concentration of H2O2, and the optimum concentration for the system of solar/S-doped TiO2 was found to be 20 mg/L, which was 5 mg/L higher than that of solar/TiO2 system. Lower water pH favored the degradation of bisphenol A, whose degradation rate coefficients at pH 5.5 were about 50% higher than that at pH 8.5. Humic acids decreased both the degradation rate of the two processes, and the influence could be fitted by second-order equation. In addition, solar/S-doped TiO2 process was more easily affected, for the humic acids could not only compete with molecular bisphenol-A for radicals but also adsorb part of visible sunlight which can excite radical with TiO2.
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PMID:[Performance of solar/S-doped TiO2 on the decomposition of bisphenol A]. 1966 46

This study aimed to prepare and characterise titanium dioxide (TiO2) nanoparticles and titanate nanotubes produced from Ti-sat flocculated sludge with drinking water (DW) and seawater (SW). The Ti-salt flocculated sludge from DW and SW was incinerated at 600 degrees C to produce TiO2 nanoparticles. XRD results showed that the anatase TiO2 structure was predominant for TiO2 from DW (TiO2-DW) and TiO2 from SW (TiO2-SW), which were mainly doped with carbon atoms. Titanate nanotubes (tiNT) were obtained when TiO2-DW and TiO2-SW were hydrothermally treated with NaOH solution. Structure phase, shape, crystallisation and photocatalytic activity of tiNT were affected by the incineration temperature and the amount of sodium present in different tiNT. The tiNT doped with thiourea incinerated at 600 degrees C presented anatase phase, showing a high increase of the degree of crystallisation with nanotube-like structures. The photocatalytic activity of these photocatalysts was evaluated using photooxidation of gaseous acetaldehyde. Thiourea doped tiNT-DW and tiNT-SW showed similar photocatalytic activity compared to commercially available TiO2-P25 under UV light and indicated a photocatalytic activity under visible light.
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PMID:Preparation and characterisation of TiO2 nanoparticle and titanate nanotube obtained from Ti-salt flocculated sludge with drinking water and seawater. 2145 56

N, S, F-co-doped TiO2 visible-light response photocatalyst (N-S-F-TiO2) was prepared with TiCl4, thiourea and ionic liquid (C6 mim]+ [BF4) via the microwave-catalytic hydrolysis precipitation process followed by calcination in an NH3/N2 atmosphere. It was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffusion reflectance spectroscopy (UV-Vis/DRS). Results showed that it was high purity anatase. The Ti-O-N, Ti-O-S and Ti-S bonds were formed in the TiO2 crystal and F used to dope TiO2 in the form of TiOF2. In the visible region 400 -550 nm, it has strong absorption, and in 600-800 nm there was a strong absorption band. N-S-F-TiO2 prepared at volume ratio of [C6 mim]+ [BF4]- /H2O of 5/95 exhibited the highest photocatalytic activity, and the degradation ratio of methyl orange was 95% under visible-light irradiation for 200 min. Multi-element co-doped synergistic effect was demonstrated by enhancement of the absorption in the visible region and higher visible light photocatalytic activity for N-S-F-TiO2.
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PMID:[Preparation and characterization of N, S, F-codoped nanosize TiO2 with ionic liquid]. 2151 Apr 19


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