Heterodinuclear titanium/zinc catalysis: synthesis, characterization and activity for CO2/epoxide copolymerization and cyclic ester polymerization.

PubMed

Garden, Jennifer A; White, Andrew J P; Williams, Charlotte K

2017-02-21

The preparation of heterodinuclear complexes, especially those comprising early-late transition metals coordinated by a simple or symmetrical ancillary ligand, represents a fundamental challenge and an opportunity to prepare catalysts benefitting from synergic properties. Here, two new mixed titanium(iv)-zinc(ii) complexes, [LTi(O i Pr) 2 ZnEt] and [LTi(O i Pr) 2 ZnPh], both coordinated by a diphenolate tetra(amine) macrocyclic ligand (L), are prepared. The synthesis benefits from the discovery that reaction of the ligand with a single equivalent of titanium tetrakis(iso-propoxide) allows the efficient formation of a mono-Ti(iv) complex, [LTi(O i Pr) 2 ]. All new complexes are characterized by a combination of single crystal X-ray diffraction, multinuclear NMR spectroscopy and mass spectrometry techniques. The two heterobimetallic complexes, [LTi(O i Pr) 2 ZnEt] and [LTi(O i Pr) 2 ZnPh], feature trianionic coordination by the macrocyclic ligand and bridging alkoxide groups coordinate to both the different metal centres. The heterodinuclear catalysts are compared to the mono-titanium analogue, [LTi(O i Pr) 2 ], in various polymerization reactions. In the alternating copolymerizations of carbon dioxide and cyclohexene oxide, the mono-titanium complex is totally inactive whilst the heterodinuclear complexes show moderate activity (TOF = 3 h -1 ); it should be noted the activity is measured using just 1 bar pressure of carbon dioxide. In the ring opening polymerization of lactide and ε-caprolactone, the mono-Ti(iv) complex is totally inactive whilst the heterodinuclear complexes show moderate-high activities, qualified by comparison to other known titanium polymerization catalysts (l-lactide, k obs = 11 × 10 -4 s -1 at 70 °C, 1 M in [lactide]) and ε-caprolactone (k obs = 5 × 10 -4 s -1 at 70 °C, 0.9 M in [ε-caprolactone]).

Titanium dioxide encapsulation of supported Ag nanoparticles on the porous silica bead for increased photocatalytic activity

NASA Astrophysics Data System (ADS)

Liu, Hui; Deng, Lu; Sun, Chaochao; Li, Junqi; Zhu, Zhenfeng

2015-01-01

A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5-10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO2 nanocrystals.

Retraction: Gold nanoparticles immobilized on electrospun titanium dioxide nanofibers for catalytic reduction of 4-nitrophenol.

PubMed

Cavusoglu, Halit; Buyukbekar, Burak Zafer; Sakalak, Huseyin; Kohsakowski, Sebastian

2017-02-13

This study involves the preparation and catalytic properties of anatase titanium dioxide nanofibers (TiO2 NFs) supported gold nanoparticles (Au NPs) using a model reaction based on the reduction of 4-nitrophenol (NP) into 4-aminophenol (AP) by sodium borohydride (NaBH4). The fabrication of surfactant-free Au NPs was performed using pulsed laser ablation in liquid (PLAL) technique. The TiO2 NFs were fabricated by a combination of electrospinning and calcination process using a solution containing poly(vinyl pyrolidone)(PVP) and titanium isopropoxide. The adsorption efficiency of laser-generated surfactant-free Au NPs to TiO2 NF supports as a function of pH was analyzed. Our results show that the electrostatic interaction mainly controls the adsorption of the nanoparticles. Au NPs/TiO2 NFs composite exhibited good catalytic activity for the reduction of 4-NP to 4-AP. The unique combination of these materials leads to the development of highly efficient catalysts. Our heterostructured nanocatalysts possibly form an efficient path to fabricate various metal NP/metal-oxide supported catalysts. Thus the applications of PLAL-noble metal NPs can widely broaden. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photocatalysis as an Effective Advanced Oxidation Process

EPA Science Inventory

Photocatalysis is generally referred to as the acceleration of a photoreaction by the presence of a semiconductor catalyst such as titanium dioxide (TiO2) or zinc oxide (ZnO). Photocatalytic materials can be prepared by using various methods such as a sol-gel process, solution pr...

Ozonation of clofibric acid catalyzed by titanium dioxide.

PubMed

Rosal, Roberto; Gonzalo, María S; Rodríguez, Antonio; García-Calvo, Eloy

2009-09-30

The removal of clofibric acid from aqueous solution has been investigated in catalytic and non-catalytic semicontinuous ozonation runs. Kinetic data were analyzed using second order expressions for the reaction between organics and ozone or hydroxyl radicals. Catalytic runs used a commercial titanium dioxide catalyst consisting of fumed colloidal particles. The kinetic constant of the non-catalytic ozonation of clofibric acid at pH 3 was 8.16 x 10(-3)+/-3.4 x 10(-4)L mmol(-1)s(-1). The extent of mineralization during non-catalytic runs ranged from 50% at pH 7 to 20% at pH 3 in a reaction that essentially took place during the first 10-20 min. The catalyst increased the total extent of mineralization, its effect being more important during the first part of the reaction. The pseudo-homogeneous catalytic rate constant was 2.17 x 10(-2) L mmol(-1)s(-1) at pH 3 and 6.80 x 10(-1)L mmol(-1)s(-1) at pH 5, with up to a threefold increase with respect to non-catalytic constants using catalyst load of 1g/L. A set of stopped-flow experiments were designed to elucidate the role of catalyst, whose effect was probably due to the adsorption of organics on catalytic sites rather than to the promotion of ozone decomposition.

BIOTEMPLATING OF TITANIUM DIOXIDE NANOPARTICLES FOR THE GREEN PRODUCTION OF PHOTOCHEMICALLY ACTIVE CATALYSTS: SYNTHESIS, CHARACTERIZATION, AND PHOTOCATALYTIC EVALUATION

EPA Science Inventory

The ability of different nano-sized materials (NSM) to effectively act as active photo-catalytic surfaces has been described for the mineralization/inactivation of many different aqueous pollutants. The reason for their enhanced ability over larger catalytic surfaces owes muc...

Visible-Light-Responsive Catalysts Using Quantum Dot-Modified TiO2 for Air and Water Purification

NASA Technical Reports Server (NTRS)

Coutts, Janelle L.; Hintze, Paul E.; Clausen, Christian; Richards, Jeffrey Todd

2014-01-01

Photocatalysis, the oxidation or reduction of contaminants by light-activated catalysts, utilizing titanium dioxide (TiO2) as the catalytic substrate has been widely studied for trace contaminant control in both air and water applications. The interest in this process is due primarily to its low energy consumption and capacity for catalyst regeneration. Titanium dioxide requires ultraviolet light for activation due to its relatively large band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors; however, the use of mercury precludes the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure. The development of a visible-light responsive (VLR) TiO2-based catalyst would eliminate the concerns over mercury contamination. Further, VLR development would allow for the use of ambient visible solar radiation or highly efficient LEDs, both of which would make PCO approaches more efficient, flexible, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts. Those VLR catalysts that are commercially available do not have adequate catalytic activity, in the visible region, to make them competitive with those operating under UV irradiation. This study was initiated to develop more effective VLR catalysts through a novel method in which quantum dots (QD) consisting of narrow band gap semiconductors (e.g., CdS, CdSe, PbS, ZnSe, etc.) are coupled to TiO2 via two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems and served as model contaminants for this research. Synthesized catalysts were compared in terms of preparation method, nature of the quantum dots, and dosage of quantum dots.

Synthesis, characterization, and photocatalytic properties of core/shell mesoporous silica nanospheres supporting nanocrystalline titania

NASA Astrophysics Data System (ADS)

Cendrowski, K.; Chen, X.; Zielinska, B.; Kalenczuk, R. J.; Rümmeli, M. H.; Büchner, B.; Klingeler, R.; Borowiak-Palen, E.

2011-11-01

The facile bulk synthesis of silica nanospheres makes them an attractive support for the transport of chemical compounds such as nanocrystalline titanium dioxide. In this contribution we present a promising route for the synthesis of mesoporous silica nanospheres (m-SiO2) with diameter in range 200 nm, which are ideal supports for nanocrystalline titanium dioxide (TiO2). The detailed microscopic and spectroscopic characterizations of core/shell structure (m-SiO2/TiO2) were conducted. Moreover, the photocatalytic potential of the nanostructures was investigated via phenol decomposition and hydrogen generation. A clear enhancement of photoactivity in both reactions as compared to commercial TiO2-Degussa P25 catalyst is detected.

SELECTIVE OXIDATION OF ALCOHOLS IN GAS PHASE USING LIGHT-ACTIVATED TITANIUM DIOXIDE

EPA Science Inventory

Selective oxidations of various primary and secondary alcohols were studied in a gas phase photochemical reactor using immobilized TiO2 catalyst. An annular photoreactor was used at 463K with an average contact time of 32sec. The system was found to be specifically suited for the...

Visible Light Responsive Catalysts Using Quantum Dot-Modified Ti02 for Air and Water Purification

NASA Technical Reports Server (NTRS)

Coutts, Janelle L.; Levine, Lanfang H.; Richards, Jeffrey T.; Hintze, paul; Clausen, Christian

2012-01-01

The method of photocatalysis utilizing titanium dioxide, TiO2, as the catalyst has been widely studied for trace contaminant control for both air and water applications because of its low energy consumption and use of a regenerable catalyst. Titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors and are a setback for the technology for space application due to the possibility of Hg contamination. The development of a visible light responsive (VLR) TiO2-based catalyst could lead to the use of solar energy in the visible region (approx.45% of the solar spectrum lies in the visible region; > 400 nm) or highly efficient LEDs (with wavelengths > 400 nm) to make PCO approaches more efficient, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts; those that are available still have poor activity in the visible region compared to that in the UV region. Thus, this study was aimed at the further development of VLR catalysts by a new method - coupling of quantum dots (QD) of a narrow band gap semiconductor (e.g., CdS, CdSe, PbS, ZnSe, etc.) to the TiO2 by two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications, using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems serve as model contaminants for this research. Synthesized catalysts were compared in terms of preparation method, type of quantum dots, and dosage of quantum dots.

Rhodamine B in dissolved and nano-bound forms: Indicators for light-based advanced oxidation processes.

PubMed

Shabat-Hadas, Efrat; Mamane, Hadas; Gitis, Vitaly

2017-10-01

Rhodamine B (RhB) is a water-soluble fluorescent dye that is often used to determine flux and flow direction in biotechnological and environmental applications. In the current research, RhB in soluble (termed free) and virus-bound (termed nano-bound) forms was used as an efficiency indicator for three environmental processes. The degradation of free and nano-bound RhB by (i) direct UV photolysis and (ii) UV/H 2 O 2 advanced oxidation process (AOP) was studied in a collimated beam apparatus equipped with medium-pressure mercury vapor lamp. The degradation by (iii) solar light-induced photocatalysis was studied in a solar simulator with titanium dioxide and bismuth photocatalysts. Results showed negligible RhB degradation by direct UV and solar light, and its nearly linear degradation by UV/H 2 O 2 and photocatalysis/photosensitization in the presence of a solid catalyst. Considerable adsorption of free RhB on bismuth-based catalyst vs. no adsorption of nano-bound RhB on this catalyst or of any form of the dye on titanium dioxide produced two important conclusions. First, the better degradation of free RhB by the bismuth catalyst suggests that close proximity of a catalyst hole and the decomposing molecule significantly influences degradation. Second, the soluble form of the dye might not be the best option for its use as an indicator. Nano-bound RhB showed high potential as an AOP indicator, featuring possible separation from water after the analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Visible-Light-Responsive Photocatalysis: Ag-Doped TiO2 Catalyst Development and Reactor Design Testing

NASA Technical Reports Server (NTRS)

Coutts, Janelle L.; Hintze, Paul E.; Meier, Anne; Shah, Malay G.; Devor, Robert W.; Surma, Jan M.; Maloney, Phillip R.; Bauer, Brint M.; Mazyck, David W.

2016-01-01

In recent years, the alteration of titanium dioxide to become visible-light-responsive (VLR) has been a major focus in the field of photocatalysis. Currently, bare titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Hg-vapor fluorescent light sources are used in photocatalytic oxidation (PCO) reactors to provide adequate levels of ultraviolet light for catalyst activation; these mercury-containing lamps, however, hinder the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure. VLR-TiO2 would allow for use of ambient visible solar radiation or highly efficient visible wavelength LEDs, both of which would make PCO approaches more efficient, flexible, economical, and safe. Over the past three years, Kennedy Space Center has developed a VLR Ag-doped TiO2 catalyst with a band gap of 2.72 eV and promising photocatalytic activity. Catalyst immobilization techniques, including incorporation of the catalyst into a sorbent material, were examined. Extensive modeling of a reactor test bed mimicking air duct work with throughput similar to that seen on the International Space Station was completed to determine optimal reactor design. A bench-scale reactor with the novel catalyst and high-efficiency blue LEDs was challenged with several common volatile organic compounds (VOCs) found in ISS cabin air to evaluate the system's ability to perform high-throughput trace contaminant removal. The ultimate goal for this testing was to determine if the unit would be useful in pre-heat exchanger operations to lessen condensed VOCs in recovered water thus lowering the burden of VOC removal for water purification systems.

Nanosized CuO and ZnO catalyst supported on titanium chip for conversion of carbon dioxide to methyl alcohol.

PubMed

Seo, Hyeong-Seok; Park, Chul-Min; Kim, Ki-Joong; Jeong, Woon-Jo; Chung, Min-Chul; Jung, Sang-Chul; Kim, Sang-Chai; Ahn, Ho-Geun

2013-08-01

In order to reutilize spent metallic titanium chips (TC) as catalyst support or photocatalytic materials, the surface of the TC was modified by thermal treatment under air atmosphere. TC-supported nanosized CuO and ZnO catalysts were prepared by impregnation (IMP) and co-precipitation (CP) method, respectively. The catalytic activity for CO2 hydrogenation to CH3OH was investigated using a flow-typed reactor under various reaction pressures. The crystals of CuO and ZnO was well formed on TC. CO2 conversion, CH3OH selectivity, and CH3OH yield were obtained as a function of time on stream over CuO-ZnO/TC catalysts. Conversion of CO2 to CH3OH over CuO-ZnO/TC catalyst by CP method and CuO/ZnO/TC catalyst by IMP method were ca. 16% and ca. 12%, respectively. Conversion of CO2 over CuO-ZnO/TC catalyst by CP method was increased with increasing reaction temperature in the range of 15-30 atm. Maximum selectivity and yield to CH3OH over CuO-ZnO/TC at 250 degrees C were ca. 90% at 20 atm and ca. 18.2% at 30 atm, respectively.

Gold nanoparticles supported on titanium dioxide: an efficient catalyst for highly selective synthesis of benzoxazoles and benzimidazoles.

PubMed

Tang, Lin; Guo, Xuefeng; Yang, Yu; Zha, Zhenggen; Wang, Zhiyong

2014-06-11

A highly efficient and selective reaction for the synthesis of 2-substituted benzoxazoles and benzimidazoles catalyzed by Au/TiO2 has been developed via two hydrogen-transfer processes. This reaction has a good tolerance to air and water, a wide substrate scope, and represents a new avenue for practical C-N and C-O bond formation. More importantly, no additional additives, oxidants and reductants are required for the reaction and the catalyst can be recovered and reused readily.

Visible-Light-Responsive Catalyst Development for Volatile Organic Carbon Remediation Project

NASA Technical Reports Server (NTRS)

Zeitlin, Nancy; Hintze, Paul E.; Coutts, Janelle

2015-01-01

Photocatalysis is a process in which light energy is used to 'activate' oxidation/reduction reactions. Unmodified titanium dioxide (TiO2), a common photocatalyst, requires high-energy UV light for activation due to its large band gap (3.2 eV). Modification of TiO2 can reduce this band gap, leading to visible-light-responsive (VLR) photocatalysts. These catalysts can utilize solar and/or visible wavelength LED lamps as an activation source, replacing mercury-containing UV lamps, to create a "greener," more energy-efficient means for air and water revitalization. Recently, KSC developed several VLR catalysts that, on preliminary evaluation, possessed high catalytic activity within the visible spectrum; these samples out-performed existing commercial VLR catalysts.

Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts

NASA Astrophysics Data System (ADS)

Shan, Junjun; Li, Mengwei; Allard, Lawrence F.; Lee, Sungsik; Flytzani-Stephanopoulos, Maria

2017-11-01

An efficient and direct method of catalytic conversion of methane to liquid methanol and other oxygenates would be of considerable practical value. However, it remains an unsolved problem in catalysis, as typically it involves expensive or corrosive oxidants or reaction media that are not amenable to commercialization. Although methane can be directly converted to methanol using molecular oxygen under mild conditions in the gas phase, the process is either stoichiometric (and therefore requires a water extraction step) or is too slow and low-yielding to be practical. Methane could, in principle, also be transformed through direct oxidative carbonylation to acetic acid, which is commercially obtained through methane steam reforming, methanol synthesis, and subsequent methanol carbonylation on homogeneous catalysts. However, an effective catalyst for the direct carbonylation of methane to acetic acid, which might enable the economical small-scale utilization of natural gas that is currently flared or stranded, has not yet been reported. Here we show that mononuclear rhodium species, anchored on a zeolite or titanium dioxide support suspended in aqueous solution, catalyse the direct conversion of methane to methanol and acetic acid, using oxygen and carbon monoxide under mild conditions. We find that the two products form through independent pathways, which allows us to tune the conversion: three-hour-long batch-reactor tests conducted at 150 degrees Celsius, using either the zeolite-supported or the titanium-dioxide-supported catalyst, yield around 22,000 micromoles of acetic acid per gram of catalyst, or around 230 micromoles of methanol per gram of catalyst, respectively, with selectivities of 60-100 per cent. We anticipate that these unusually high activities, despite still being too low for commercial application, may guide the development of optimized catalysts and practical processes for the direct conversion of methane to methanol, acetic acid and other useful chemicals.

Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shan, Junjun; Li, Mengwei; Allard, Lawrence F.

An efficient and direct method of catalytic conversion of methane to liquid methanol and other oxygenates would be of considerable practical value. However, it remains an unsolved problem in catalysis, as typically it involves expensive or corrosive oxidants or reaction media(5-8) that are not amenable to commercialization. Although methane can be directly converted to methanol using molecular oxygen under mild conditions in the gas phase, the process is either stoichiometric (and therefore requires a water extraction step) or is too slow and low-yielding to be practical. Methane could, in principle, also be transformed through direct oxidative carbonylation to acetic acid,more » which is commercially obtained through methane steam reforming, methanol synthesis, and subsequent methanol carbonylation on homogeneous catalysts. However, an effective catalyst for the direct carbonylation of methane to acetic acid, which might enable the economical small-scale utilization of natural gas that is currently flared or stranded, has not yet been reported. Here we show that mononuclear rhodium species, anchored on a zeolite or titanium dioxide support suspended in aqueous solution, catalyse the direct conversion of methane to methanol and acetic acid, using oxygen and carbon monoxide under mild conditions. Here, we find that the two products form through independent pathways, which allows us to tune the conversion: three-hour-long batch-reactor tests conducted at 150 degrees Celsius, using either the zeolitesupported or the titanium-dioxide-supported catalyst, yield around 22,000 micromoles of acetic acid per gram of catalyst, or around 230 micromoles of methanol per gram of catalyst, respectively, with selectivities of 60-100 per cent. Finally, we anticipate that these unusually high activities, despite still being too low for commercial application, may guide the development of optimized catalysts and practical processes for the direct conversion of methane to methanol, acetic acid and other useful chemicals.« less

Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts

DOE PAGES

Shan, Junjun; Li, Mengwei; Allard, Lawrence F.; ...

2017-11-30

An efficient and direct method of catalytic conversion of methane to liquid methanol and other oxygenates would be of considerable practical value. However, it remains an unsolved problem in catalysis, as typically it involves expensive or corrosive oxidants or reaction media(5-8) that are not amenable to commercialization. Although methane can be directly converted to methanol using molecular oxygen under mild conditions in the gas phase, the process is either stoichiometric (and therefore requires a water extraction step) or is too slow and low-yielding to be practical. Methane could, in principle, also be transformed through direct oxidative carbonylation to acetic acid,more » which is commercially obtained through methane steam reforming, methanol synthesis, and subsequent methanol carbonylation on homogeneous catalysts. However, an effective catalyst for the direct carbonylation of methane to acetic acid, which might enable the economical small-scale utilization of natural gas that is currently flared or stranded, has not yet been reported. Here we show that mononuclear rhodium species, anchored on a zeolite or titanium dioxide support suspended in aqueous solution, catalyse the direct conversion of methane to methanol and acetic acid, using oxygen and carbon monoxide under mild conditions. Here, we find that the two products form through independent pathways, which allows us to tune the conversion: three-hour-long batch-reactor tests conducted at 150 degrees Celsius, using either the zeolitesupported or the titanium-dioxide-supported catalyst, yield around 22,000 micromoles of acetic acid per gram of catalyst, or around 230 micromoles of methanol per gram of catalyst, respectively, with selectivities of 60-100 per cent. Finally, we anticipate that these unusually high activities, despite still being too low for commercial application, may guide the development of optimized catalysts and practical processes for the direct conversion of methane to methanol, acetic acid and other useful chemicals.« less

Development and Characterization of Titanium Dioxide Gel with Encapsulated Bacteriorhodopsin for Hydrogen Production.

PubMed

Johnson, Kaitlin E; Gakhar, Sukriti; Risbud, Subhash H; Longo, Marjorie L

2018-06-06

We study bacteriorhodopsin (BR) in its native purple membrane encapsulated within amorphous titanium dioxide, or titania, gels and in the presence of titania sol-particles to explore this system for hydrogen production. Förster resonance energy transfer between BR and titanium dioxide sol particles was used to conclude that there is nanometer-scale proximity of bacteriorhodopsin to the titanium dioxide. The detection of BR-titania sol aggregates by fluorescence anisotropy and particle sizing indicated the affinity amorphous titania has for BR without the use of additional cross-linkers. UV-Visible spectroscopy of BR-titania gels show that methanol addition did not denature BR at a 25 mM concentration presence as a sacrificial electron donor. Additionally, confinement of BR in the gels significantly limited protein denaturation at higher concentration of added methanol or ethanol. Subsequently, titania gels fabricated through the sol-gel process using a titanium ethoxide precursor, water and the addition of 25 mM methanol were used to encapsulate BR and a platinum reduction catalyst for the production of hydrogen gas under white light irradiation. The inclusion of 5 µM bacteriorhodopsin resulted in a hydrogen production rate of about 3.8 µmole hydrogen mL -1 hr -1 , an increase of 52% compared to gels containing no protein. Electron transfer and proton pumping by BR in close proximity to the titania gel surface are feasible explanations for the enhanced production of hydrogen without the need to crosslink BR to the titania gel. This work sets the stage for further developments of amorphous, rather than crystalline, titania-encapsulated bacteriorhodopsin for solar-driven hydrogen production through water-splitting.

Bibliography of work on the heterogeneous photocatalytic removal of hazardous compounds from water and air: Update Number 1 to June, 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blake, D.M.

1995-11-01

This report is an update of a bibliography, published in May, 1994, of research performed on the photocatalytic oxidation of organic or inorganic compounds in air or water and on the photocatalytic reduction of metal-containing ions in water. The general focus of the research is on removing hazardous contaminants from air water to meet environmental or health regulations. The processes covered are based on the application of heterogeneous photocatalysts. The current state-of-the-art in catalysts are forms of titanium dioxide or modifications of titanium dioxide, but work on other heterogeneous catalysts is also included in this compilation. This update contains 574more » references, most published between January, 1993 and June, 1995, but some references are from earlier work that were not included in the previous report. A new section has been added which gives information about companies that are active in providing products based on photocatalytic processes or that can provide pilot, demonstration, or commercial-scale water- or air-treatment systems. Key words, assigned by the author of this report, have been included with the citations in the listing of the bibliography.« less

Effect of catalysts on dc corona discharge poisoning

NASA Astrophysics Data System (ADS)

Pekárek, S.

2011-02-01

The processes of ozone generation in non-thermal plasma produced by an electrical discharge in air at atmospheric pressure are burdened by the presence of nitrogen oxides, which on the one hand contribute to ozone generation and on the other hand are responsible for unpleasant discharge poisoning. The term discharge poisoning refers to the situation when the discharge ozone formation completely breaks down. Discharge poisoning can be affected by placing a catalyst in the discharge chamber. For the dc hollow needle to mesh corona discharge enhanced by the flow of air through the needle electrode we studied the effect of titanium dioxide TiO2, ZSM-5 zeolite or Cu++ZSM-5 zeolite on discharge poisoning by monitoring the ozone, nitrogen monoxide and nitrogen dioxide discharge production. We found that placing globules of any of these catalysts on the mesh decreases the energy density of the onset of discharge poisoning, and this energy density is smallest for a discharge with globules of a TiO2 on the mesh.

Photocatalytic oxidation of organic compounds on Mars

NASA Technical Reports Server (NTRS)

Chun, S. F. S.; Pang, K. D.; Cutts, J. A.; Ajello, J. M.

1978-01-01

Ultraviolet-stimulated catalytic oxidation is proposed as a mechanism for the destruction of organic compounds on Mars. The process involves the presence of gaseous oxygen, UV radiation, and a catalyst (titanium dioxide), and all three of these have been found to be present in the Martian environment. Therefore it seems plausible that UV-stimulated oxidation of organics is responsible for degrading organic molecules into inorganic end products.

Virus inactivation by silver doped titanium dioxide nanoparticles for drinking water treatment.

PubMed

Liga, Michael V; Bryant, Erika L; Colvin, Vicki L; Li, Qilin

2011-01-01

Photocatalytic inactivation of viruses and other microorganisms is a promising technology that has been increasingly utilized in recent years. In this study, photocatalytic silver doped titanium dioxide nanoparticles (nAg/TiO(2)) were investigated for their capability of inactivating Bacteriophage MS2 in aqueous media. Nano-sized Ag deposits were formed on two commercial TiO(2) nanopowders using a photochemical reduction method. The MS2 inactivation kinetics of nAg/TiO(2) was compared to the base TiO(2) material and silver ions leached from the catalyst. The inactivation rate of MS2 was enhanced by more than 5 fold depending on the base TiO(2) material, and the inactivation efficiency increased with increasing silver content. The increased production of hydroxyl free radicals was found to be responsible for the enhanced viral inactivation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Engineering-scale experiments of solar photocatalytic oxidation of trichloroethylene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pacheco, J.; Prairie, M.; Evans, L.

1990-01-01

A photocatalytic process is being developed to destroy organic contaminants in water. Tests with a common water pollutant, trichlorethylene (TCE), were conducted at the Solar Thermal Test Facility at Sandia with trough systems. Tests at this scale provide verification of laboratory studies and allow examination of design and operation issues that only arise in experiments on a realistic scale. The catalyst, titanium dioxide (TiO{sub 2}), is a harmless material found in paint, cosmetics and even toothpaste. We examined the effect of initial contaminant concentration and the effect of hydrogen peroxide on the photocatalytic decomposition of trichlorethylene (TCE). An aqueous solutionmore » of 5000 parts per billion (ppB) TCE with 0.1 weight {percent} suspended titanium dioxide catalyst required approximately 4.2 minutes of exposure to destroy the TCE to a detection limit of 5 ppB. For a 300 ppB TCE solution, the time required was only 2.5 minutes to reach the same level of destruction. Adding 250 parts per million (ppM) of hydrogen peroxide reduced the time required by about 1 minute. A two parameter Langmuir Hinshelwood model was able to describe the data. A simple flow apparatus was built to test four fixed catalyst supports and to measure their pressure drop and assess their ability to withstand flow conditions typical of a full-sized system. In this paper, we summarize the engineering-scale testing and results. 16 refs., 5 figs.« less

Anatase vs. rutile efficiency on the photocatalytic degradation of clofibric acid under near UV to visible irradiation.

PubMed

Silva, Cláudia Gomes; Faria, Joaquim Luís

2009-05-01

Titanium dioxide (TiO(2)) powder, a semiconductor material typically used as a photocatalyst, is prepared following an acid-catalyzed sol-gel method starting from titanium isopropoxide. The xerogel calcination temperature is used to control surface and morphological properties of the material. Materials are extensively characterized by spectroscopic, micrographic and calorimetric techniques. The different TiO(2) catalysts are used in the visible-light-driven photocatalytic degradation of clofibric acid, a lipid regulator drug. The photoefficiency of TiO(2) catalysts, quantified in terms of kinetic rate constant, total organic carbon removal and initial quantum yield, increases with calcination temperature up to 673 K. A further increase in the calcination temperature leads to a decline in the photoefficiency of the catalysts, which is associated with the phase transformation from anatase to rutile concomitant with an increase in crystallite dimensions. The photochemical and photocatalytic oxidation of clofibric acid follows a pseudo-first order kinetic rate law. 4-Chlorophenol, isobutyric acid, hydroquinone, benzoquinone and 4-chlorocatechol are detected as main intermediates.

Cadmium Telluride-Titanium Dioxide Nanocomposite for Photodegradation of Organic Substance.

PubMed

Ontam, Areeporn; Khaorapapong, Nithima; Ogawa, Makoto

2015-12-01

Cadmium telluride-titanium dioxide nanocomposite was prepared by hydrothermal reaction of sol-gel derived titanium dioxide and organically modified cadmium telluride. The crystallinity of titanium dioxide in the nanocomposite was higher than that of pure titanium dioxide obtained by the reaction under the same temperature and pressure conditions, showing that cadmium telluride induced the crystallization of titanium dioxide. Diffuse reflectance spectrum of the nanocomposite showed the higher absorption efficiency in the UV-visible region due to band-gap excitation of titanium dioxide. The nanocomposite significantly showed the improvement of photocatalytic activity for 4-chlorophenol with UV light.

Phenol Photocatalytic Degradation by Advanced Oxidation Process under Ultraviolet Radiation Using Titanium Dioxide

PubMed Central

Nickheslat, Ali; Amin, Mohammad Mehdi; Izanloo, Hassan; Fatehizadeh, Ali; Mousavi, Seyed Mohammad

2013-01-01

Background. The main objective of this study was to examine the photocatalytic degradation of phenol from laboratory samples and petrochemical industries wastewater under UV radiation by using nanoparticles of titanium dioxide coated on the inner and outer quartz glass tubes. Method. The first stage of this study was conducted to stabilize the titanium dioxide nanoparticles in anatase crystal phase, using dip-coating sol-gel method on the inner and outer surfaces of quartz glass tubes. The effect of important parameters including initial phenol concentration, TiO2 catalyst dose, duration of UV radiation, pH of solution, and contact time was investigated. Results. In the dip-coat lining stage, the produced nanoparticles with anatase crystalline structure have the average particle size of 30 nm and are uniformly distributed over the tube surface. The removal efficiency of phenol was increased with the descending of the solution pH and initial phenol concentration and rising of the contact time. Conclusion. Results showed that the light easily passes through four layers of coating (about 105 nm). The highest removal efficiency of phenol with photocatalytic UV/TiO2 process was 50% at initial phenol concentration of 30 mg/L, solution pH of 3, and 300 min contact time. The comparison of synthetic solution and petrochemical wastewater showed that at same conditions the phenol removal efficiency was equal. PMID:23710198

Ultra-rapid photocatalytic activity of Azadirachta indica engineered colloidal titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Sankar, Renu; Rizwana, Kadarmohideen; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2015-08-01

Titanium dioxide nanoparticles were effectively synthesized from aqueous leaf extract of Azadirachta indica under pH and temperature-dependent condition. 5 mM titanium isopropoxide solution worked as a primary source for the synthesis of titanium dioxide nanoparticles. The green synthesized titanium dioxide nanoparticles were confirmed by UV-Vis spectroscopy. Fourier transform infrared spectrum of synthesized titanium dioxide nanoparticles authorized the presence of bioactive compounds in the leaf extract, which may play a role as capping and reducing agent. The high-resolution scanning electron microscopy and dynamic light scattering analyses results showed the interconnected spherical in shape titanium dioxide nanoparticles having a mean particle size of 124 nm and a zeta potential of -24 mV. Besides, the colloidal titanium dioxide nanoparticles energetically degrade the industrially harmful methyl red dye under bright sunlight.

40 CFR 180.1195 - Titanium dioxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide is exempted from the requirement of a tolerance for residues in or on...

40 CFR 180.1195 - Titanium dioxide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide is exempted from the requirement of a tolerance for residues in or on...

40 CFR 180.1195 - Titanium dioxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide is exempted from the requirement of a tolerance for residues in or on...

40 CFR 415.220 - Applicability; description of the titanium dioxide production subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... titanium dioxide production subcategory. 415.220 Section 415.220 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.220 Applicability; description of the titanium dioxide production subcategory. This subpart applies to discharges to waters of the United States...

40 CFR 415.220 - Applicability; description of the titanium dioxide production subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... titanium dioxide production subcategory. 415.220 Section 415.220 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.220 Applicability; description of the titanium dioxide production subcategory. This subpart applies to discharges to waters of the United States...

40 CFR 415.220 - Applicability; description of the titanium dioxide production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... titanium dioxide production subcategory. 415.220 Section 415.220 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.220 Applicability; description of the titanium dioxide production subcategory. This subpart applies to discharges to waters of the United States...

40 CFR 415.220 - Applicability; description of the titanium dioxide production subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... titanium dioxide production subcategory. 415.220 Section 415.220 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.220 Applicability; description of the titanium dioxide production subcategory. This subpart applies to discharges to waters of the United States...

40 CFR 415.220 - Applicability; description of the titanium dioxide production subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... titanium dioxide production subcategory. 415.220 Section 415.220 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.220 Applicability; description of the titanium dioxide production subcategory. This subpart applies to discharges to waters of the United States...

21 CFR 73.1575 - Titanium dioxide.

Code of Federal Regulations, 2010 CFR

2010-04-01

... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the requirements of § 73.575(a)(1) and (b). (2) Color additive mixtures for drug use made with titanium dioxide may...

21 CFR 73.1575 - Titanium dioxide.

Code of Federal Regulations, 2012 CFR

2012-04-01

... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the requirements of § 73.575(a)(1) and (b). (2) Color additive mixtures for drug use made with titanium dioxide may...

21 CFR 73.1575 - Titanium dioxide.

Code of Federal Regulations, 2013 CFR

2013-04-01

... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the requirements of § 73.575(a)(1) and (b). (2) Color additive mixtures for drug use made with titanium dioxide may...

21 CFR 73.1575 - Titanium dioxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the requirements of § 73.575(a)(1) and (b). (2) Color additive mixtures for drug use made with titanium dioxide may...

Creation of high-refractive-index amorphous titanium oxide thin films from low-fractal-dimension polymeric precursors synthesized by a sol-gel technique with a hydrazine monohydrochloride catalyst.

PubMed

Shimizu, Wataru; Nakamura, Satoshi; Sato, Takaaki; Murakami, Yasushi

2012-08-21

Amorphous titanium dioxide (TiO(2)) thin films exhibiting high refractive indices (n ≈ 2.1) and high transparency were fabricated by spin-coating titanium oxide liquid precursors having a weakly branched polymeric structure. The precursor solution was prepared from titanium tetra-n-butoxide (TTBO) via the catalytic sol-gel process with hydrazine monohydrochloride used as a salt catalyst, which serves as a conjugate acid-base pair catalyst. Our unique catalytic sol-gel technique accelerated the overall polycondensation reaction of partially hydrolyzed alkoxides, which facilitated the formation of liner polymer-like titanium oxide aggregates having a low fractal dimension of ca. (5)/(3), known as a characteristic of the so-called "expanded polymer chain". Such linear polymeric features are essential to the production of highly dense amorphous TiO(2) thin films; mutual interpenetration of the linear polymeric aggregates avoided the creation of void space that is often generated by the densification of high-fractal-dimension (particle-like) aggregates produced in a conventional sol-gel process. The mesh size of the titanium oxide polymers can be tuned either by water concentration or the reaction time, and the smaller mesh size in the liquid precursor led to a higher n value of the solid thin film, thanks to its higher local electron density. The reaction that required no addition of organic ligand to stabilize titanium alkoxides was advantageous to overcoming issues from organic residues such as coloration. The dense amorphous film structure suppressed light scattering loss owing to its extremely smooth surface and the absence of inhomogeneous grains or particles. Furthermore, the fabrication can be accomplished at a low heating temperature of <80 °C. Indeed, we successfully obtained a transparent film with a high refractive index of n = 2.064 (at λ = 633 nm) on a low-heat-resistance plastic, poly(methyl methacrylate), at 60 °C. The result offers an efficient route to high-refractive-index amorphous TiO(2) films as well as base materials for a wider range of applications.

The preparation and the sustained release of titanium dioxide hollow particles encapsulating L-ascorbic acid

NASA Astrophysics Data System (ADS)

Tominaga, Yoko; Kadota, Kazunori; Shimosaka, Atsuko; Yoshida, Mikio; Oshima, Kotaro; Shirakawa, Yoshiyuki

2018-05-01

The preparation of the titanium dioxide hollow particles encapsulating L-ascorbic acid via sol-gel process using inkjet nozzle has been performed, and the sustained release and the effect protecting against degradation of L-ascorbic acid in the particles were investigated. The morphology of titanium dioxide particles was evaluated by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The sustained release and the effect protecting against degradation of L-ascorbic acid were estimated by dialysis bag method in phosphate buffer saline (PBS) (pH = 7.4) as release media. The prepared titanium dioxide particles exhibited spherical porous structures. The particle size distribution of the titanium dioxide particles was uniform. The hollow titanium dioxide particles encapsulating L-ascorbic acid showed the sustained release. It was also found that the degradation of L-ascorbic acid could be inhibited by encapsulating L-ascorbic acid in the titanium dioxide hollow particles.

Characterization and morphology of prepared titanium dioxide nanofibers by electrospinning.

PubMed

Park, Ju-Young; Lee, In-Hwa

2010-05-01

Dispersed titanium dioxide in polymer nanofibers were prepared by sol-gel processing and electrospinning techniques using titanium isopropoxide (TiP)/polyvinylpyrrolidone (PVP) solution. The prepared titanium dioxide nanofibers were characterized by FE-SEM, TEM, XRD, and FT-IR. Pure titanium dioxide nanofibers were obtained from calcination of inorganic-organic composite fiber. The diameter of titanium oxide nanofibers were in the range of 70 nm to 150 nm. Prepared titanium dioxide nanofibers show rough surface and rather small diameter compare with TiP/PVP composite nanofibers. After calcined at 500 degrees C, TiO2 nanofibers convert into anatase and rutile mixed phased from amorphous structure. Calcination of these composite fibers above 600 degrees C resulted in pure rutile TiO2 nanofibers.

Array of titanium dioxide nanostructures for solar energy utilization

DOEpatents

Qiu, Xiaofeng; Parans Paranthaman, Mariappan; Chi, Miaofang; Ivanov, Ilia N; Zhang, Zhenyu

2014-12-30

An array of titanium dioxide nanostructures for solar energy utilization includes a plurality of nanotubes, each nanotube including an outer layer coaxial with an inner layer, where the inner layer comprises p-type titanium dioxide and the outer layer comprises n-type titanium dioxide. An interface between the inner layer and the outer layer defines a p-n junction.

Construction of High Activity Titanium Dioxide Crystal Surface Heterostructures and Characterization of Its Basic Properties

NASA Astrophysics Data System (ADS)

Wang, Chunxiao; Li, DanQi; Shen, Tingting; Lu, Cheng; Sun, Jing; Wang, Xikui

2018-01-01

Heterogeneous photocatalytic materials, which combine the advantages of photocatalytic materials and heterojunction, have been developed rapidly in the field of environmental pollution control. In this paper, TiO2 surface heterojunction catalysts with different catalytic activity were prepared by controlling the amount of HF, and their XRD characterization was also carried out. In addition, the optimum amount of HF was determined by photocatalytic degradation of simulated dye wastewater by methylene blue solution. And the optimal amount of catalyst and the optimal pH reaction conditions for degradation experiments were used to screen the highly reactive titania surface heterojunction system and its optimum application conditions. It provides the possibility of application in the degradation of industrial wastewater and environmental treatment.

Preparation and photocatalytic activity of magnetic samarium-doped mesoporous titanium dioxide at the decomposition of methylene blue under visible light

NASA Astrophysics Data System (ADS)

Shi, Zhongliang; Lai, Hong; Yao, Shuhua

2012-08-01

Preparation of samarium-doped mesoporous titanium dioxide (Sm/MTiO2) coated magnetite (Fe3O4) photocatalysts (Sm/MTiO2/Fe3O4) and their activities under visible light were reported. The catalysts with Sm/MTiO2 shell and a Fe3O4 core were prepared by coating photoactive Sm/MTiO2 onto a magnetic Fe3O4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu)4, TBT) with precursors of Sm(NO3)3 and TBT in the presence of Fe3O4 nanoparticles. The morphological, structural and optical properties of the prepared samples were characterized by BET surface area, transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of Sm ion content on the photocatalytic activity was studied. The photocatalytic activities of obtained photocatalysts under visible light were estimated by measuring the decomposition rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Sm/MTiO2 was tightly bound to Fe3O4 and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.

Sun protection enhancement of titanium dioxide crystals by the use of carnauba wax nanoparticles: the synergistic interaction between organic and inorganic sunscreens at nanoscale.

PubMed

Villalobos-Hernández, J R; Müller-Goymann, C C

2006-09-28

Carnauba wax is partially composed of cinnamates. The rational combination of cinnamates and titanium dioxide has shown a synergistic effect to improve the sun protection factor (SPF) of cosmetic preparations. However, the mechanism of this interaction has not been fully understood. In this study, an ethanolic extract of the carnauba wax and an ethanolic solution of a typical cinnamate derivative, ethylcinnamate, were prepared and their UV absorption and SPF either alone or in the presence of titanium dioxide were compared. The titanium dioxide crystals and the cinnamates solutions were also distributed into a matrix composed of saturated fatty acids to emulate the structure of the crystallized carnauba wax. SPF, differential scanning calorimetry (DSC) and X-ray studies of these matrices were performed. Additionally, carnauba wax nanosuspensions containing titanium dioxide either in the lipid phase or in the aqueous phase were prepared to evaluate their SPFs and their physical structure. Strong UV absorption was observed in diluted suspensions of titanium dioxide after the addition of cinnamates. The saturated fatty acid matrices probably favored the adsorption of the cinnamates at the surface of titanium dioxide crystals, which was reflected by an increase in the SPF. No modification of the crystal structure of the fatty acid matrices was observed after the addition of cinnamates or titanium dioxide. The distribution of the titanium dioxide inside the lipid phase of the nanosuspensions was more effective to reach higher SPFs than that at the aqueous phase. The close contact between the carnauba wax and the titanium dioxide crystals after the high-pressure homogenization process was confirmed by transmission electron microscopy (TEM).

Imaging flow cytometry assays for quantifying pigment grade titanium dioxide particle internalization and interactions with immune cells in whole blood

PubMed Central

Vis, Bradley; Pele, Laetitia C.; Faria, Nuno; Powell, Jonathan J.

2017-01-01

Abstract Pigment grade titanium dioxide is composed of sub‐micron sized particles, including a nanofraction, and is widely utilized in food, cosmetic, pharmaceutical, and biomedical industries. Oral exposure to pigment grade titanium dioxide results in at least some material entering the circulation in humans, although subsequent interactions with blood immune cells are unknown. Pigment grade titanium dioxide is employed for its strong light scattering properties, and this work exploited that attribute to determine whether single cell–particle associations could be determined in immune cells of human whole blood at “real life” concentrations. In vitro assays, initially using isolated peripheral blood mononuclear cells, identified titanium dioxide associated with the surface of, and within, immune cells by darkfield reflectance in imaging flow cytometry. This was confirmed at the population level by side scatter measurements using conventional flow cytometry. Next, it was demonstrated that imaging flow cytometry could quantify titanium dioxide particle‐bearing cells, within the immune cell populations of fresh whole blood, down to titanium dioxide levels of 10 parts per billion, which is in the range anticipated for human blood following titanium dioxide ingestion. Moreover, surface association and internal localization of titanium dioxide particles could be discriminated in the assays. Overall, results showed that in addition to the anticipated activity of blood monocytes internalizing titanium dioxide particles, neutrophil internalization and cell membrane adhesion also occurred, the latter for both phagocytic and nonphagocytic cell types. What happens in vivo and whether this contributes to activation of one or more of these different cells types in blood merits further attention. © 2017 The Authors. Cytometry Part A Published by Wiley Periodicals, Inc. on behalf of ISAC. PMID:28941170

Summary of engineering-scale experiments for the Solar Detoxification of Water project

NASA Astrophysics Data System (ADS)

Pacheco, J. E.; Yellowhorse, L.

1992-03-01

This report contains a summary of large-scale experiments conducted at Sandia National Laboratories under the Solar Detoxification of Water project. The objectives of the work performed were to determine the potential of using solar radiation to destroy organic contaminants in water by photocatalysis and to develop the process and improve its performance. For these experiments, we used parabolic troughs to focus sunlight onto glass pipes mounted at the trough's focus. Water spiked with a contaminant and containing suspended titanium dioxide catalyst was pumped through the illuminated glass pipe, activating the catalyst with the ultraviolet portion of the solar spectrum. The activated catalyst creates oxidizers that attack and destroy the organics. Included in this report are a summary and discussion of the implications of experiments conducted to determine: the effect of process kinetics on the destruction of chlorinated solvents (such as trichloroethylene, perchloroethylene, trichloroethane, methylene chloride, chloroform and carbon tetrachloride), the enhancement due to added hydrogen peroxide, the optimal catalyst loading, the effect of light intensity, the inhibition due to bicarbonates, and catalyst issues.

40 CFR 98.310 - Definition of the source category.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.310 Definition of the source category. The titanium dioxide production source category consists of facilities that use the chloride process to produce titanium dioxide. ...

40 CFR 98.310 - Definition of the source category.

Code of Federal Regulations, 2014 CFR

2014-07-01

... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.310 Definition of the source category. The titanium dioxide production source category consists of facilities that use the chloride process to produce titanium dioxide. ...

40 CFR 98.310 - Definition of the source category.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.310 Definition of the source category. The titanium dioxide production source category consists of facilities that use the chloride process to produce titanium dioxide. ...

40 CFR 98.310 - Definition of the source category.

Code of Federal Regulations, 2013 CFR

2013-07-01

... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.310 Definition of the source category. The titanium dioxide production source category consists of facilities that use the chloride process to produce titanium dioxide. ...

40 CFR 98.310 - Definition of the source category.

Code of Federal Regulations, 2012 CFR

2012-07-01

... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Titanium Dioxide Production § 98.310 Definition of the source category. The titanium dioxide production source category consists of facilities that use the chloride process to produce titanium dioxide. ...

Nanocrystalline heterojunction materials

DOEpatents

Elder, Scott H.; Su, Yali; Gao, Yufei; Heald, Steve M.

2003-07-15

Mesoporous nanocrystalline titanium dioxide heterojunction materials are disclosed. In one disclosed embodiment, materials comprising a core of titanium dioxide and a shell of a molybdenum oxide exhibit a decrease in their photoadsorption energy as the size of the titanium dioxide core decreases.

Effect of Novel Quercetin Titanium Dioxide-Decorated Multi-Walled Carbon Nanotubes Nanocomposite on Bacillus subtilis Biofilm Development

PubMed Central

Raie, Diana S.; Mhatre, Eisha; El-Desouki, Doaa S.; Labena, Ahmed; El-Ghannam, Gamal; Farahat, Laila A.; Youssef, Tareq; Fritzsche, Wolfgang; Kovács, Ákos T.

2018-01-01

The present work was targeted to design a surface against cell seeding and adhering of bacteria, Bacillus subtilis. A multi-walled carbon nanotube/titanium dioxide nano-power was produced via simple mixing of carbon nanotube and titanium dioxide nanoparticles during the sol-gel process followed by heat treatment. Successfully, quercetin was immobilized on the nanocomposite via physical adsorption to form a quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite. The adhesion of bacteria on the coated-slides was verified after 24 h using confocal laser-scanning microscopy. Results indicated that the quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite had more negativity and higher recovery by glass surfaces than its counterpart. Moreover, coating surfaces with the quercetin-modified nanocomposite lowered both hydrophilicity and surface-attached bacteria compared to surfaces coated with the multi-walled carbon nanotubes/titanium dioxide nanocomposite. PMID:29346268

Design and development of a new generation of UV-visible-light-driven nanosized codoped titanium dioxide photocatalysts and biocides/sporocides, and environmental applications

NASA Astrophysics Data System (ADS)

Hamal, Dambar B.

For solar environmental remediation, a new generation of nanosized (< 10 nm) titanium dioxide photocatalysts codoped with metals and nonmetals, or metals only were prepared by the xero-gel and aero-gel methods. For silver or cobalt-based xero-gel titanium dioxide photocatalysts, photoactivities tests revealed that codoping of titanium dioxide with a metal (1% Ag or 2% Co) and nonmetals (carbon and sulfur) is necessary to achieve high-activities for acetaldehyde degradation under visible light (wavelength > 420 nm). It was concluded that high visible-light-activities for acetaldehyde degradation over codoped titanium dioxide were attributed to an interplay of anatase crystallinity, high-surface area, reduced band-gap (< 3.0 eV), uniform dispersion of doped metal ions, and suppressed recombination rate of photogenerated electronhole pairs. Moreover, the nature and amount of codoped metals play a significant role in visible-light-induced photocatalysis. Metals (Al, Ga, and In) doped/codoped titanium dioxide photocatalysts were prepared by the aero-gel method. The photocatalytic studies showed that activities of metal doped/codoped photocatalysts under UV light (wavelength < 400 nm) were found to be dependent on pollutants. Indium demonstrated beneficial effects in both textural and photocatalytic properties. Gallium and indium codoped titanium dioxide photocatalysts displayed even better performance in the CO oxidation reaction under UV light. Notably, titanium dioxide codoped with Ga, In, and Pt, exhibited unique photoactivities for the CO oxidation under both UV and visible light irradiation, indicating that this system could have promise for the water-gas shift reaction for hydrogen production. Silver-based nanostructured titanium dioxide samples were developed for killing human pathogens (Escherichia coli cells and Bacillus subtilis spores). Biocidal tests revealed that silver, carbon, and sulfur codoped titanium dioxide nanoparticles (< 10 nm) possess very strong antimicrobial actions on both E. coli (logarithmic kill > 8) and B. subtilis spores (logarithmic kill > 5) for 30 minute exposures in dark conditions compared with Degussa P25. It was believed that the carbon and sulfur codoped titanium dioxide support and Ag species acted synergistically during deactivation of both E. coli and B. subtilis spores. Thus, titanium dioxide codoped with silver, carbon, sulfur can serve as a multifunctional generic biocide and a visible-light-active photocatalyst.

Method for synthesis of titanium dioxide nanotubes using ionic liquids

DOEpatents

Qu, Jun; Luo, Huimin; Dai, Sheng

2013-11-19

The invention is directed to a method for producing titanium dioxide nanotubes, the method comprising anodizing titanium metal in contact with an electrolytic medium containing an ionic liquid. The invention is also directed to the resulting titanium dioxide nanotubes, as well as devices incorporating the nanotubes, such as photovoltaic devices, hydrogen generation devices, and hydrogen detection devices.

21 CFR 73.2575 - Titanium dioxide.

Code of Federal Regulations, 2010 CFR

2010-04-01

... consistent with good manufacturing practice. (c) Labeling requirements. The color additive and any mixtures... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in identity and specifications to the requirements...

40 CFR 415.225 - New source performance standards (NSPS).

Code of Federal Regulations, 2013 CFR

2013-07-01

... GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Titanium Dioxide Production... producing titanium dioxide by the sulfate process must achieve the following new source performance standards (NSPS): Subpart V—Titanium Dioxide-Sulfate Process Pollutant or pollutant property NSPS effluent...

40 CFR 415.225 - New source performance standards (NSPS).

Code of Federal Regulations, 2010 CFR

2010-07-01

... GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Titanium Dioxide Production... producing titanium dioxide by the sulfate process must achieve the following new source performance standards (NSPS): Subpart V—Titanium Dioxide-Sulfate Process Pollutant or pollutant property NSPS effluent...

40 CFR 415.225 - New source performance standards (NSPS).

Code of Federal Regulations, 2014 CFR

2014-07-01

... GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Titanium Dioxide Production... producing titanium dioxide by the sulfate process must achieve the following new source performance standards (NSPS): Subpart V—Titanium Dioxide-Sulfate Process Pollutant or pollutant property NSPS effluent...

40 CFR 415.225 - New source performance standards (NSPS).

Code of Federal Regulations, 2012 CFR

2012-07-01

... GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Titanium Dioxide Production... producing titanium dioxide by the sulfate process must achieve the following new source performance standards (NSPS): Subpart V—Titanium Dioxide-Sulfate Process Pollutant or pollutant property NSPS effluent...

40 CFR 415.225 - New source performance standards (NSPS).

Code of Federal Regulations, 2011 CFR

2011-07-01

... GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Titanium Dioxide Production... producing titanium dioxide by the sulfate process must achieve the following new source performance standards (NSPS): Subpart V—Titanium Dioxide-Sulfate Process Pollutant or pollutant property NSPS effluent...

Coated mesh photocatalytic reactor for air treatment applications: comparative study of support materials.

PubMed

Passalía, Claudio; Nocetti, Emanuel; Alfano, Orlando; Brandi, Rodolfo

2017-03-01

An experimental comparative study of different meshes as support materials for photocatalytic applications in gas phase is presented. The photocatalytic oxidation of dichloromethane in air was addressed employing different coated meshes in a laboratory-scale, continuous reactor. Two fiberglass meshes and a stainless steel mesh were studied regarding the catalyst load, adherence, and catalytic activity. Titanium dioxide photocatalyst was immobilized on the meshes by dip-coating cycles. Results indicate the feasibility of the dichloromethane elimination in the three cases. When the number of coating cycles was doubled, the achieved conversion levels were increased twofold for stainless steel and threefold for the fiberglass meshes. One of the fiberglass meshes (FG2) showed the highest reactivity per mass of catalyst and per catalytic surface area.

Nanocrystalline Heterojunction Materials

DOEpatents

Elder, Scott H.; Su, Yali; Gao, Yufei; Heald, Steve M.

2004-02-03

Mesoporous nanocrystalline titanium dioxide heterojunction materials and methods of making the same are disclosed. In one disclosed embodiment, materials comprising a core of titanium dioxide and a shell of a molybdenum oxide exhibit a decrease in their photoadsorption energy as the size of the titanium dioxide core decreases.

Challenges associated with performing environmental research on titanium dioxide nanoparticles in aquatic environments

EPA Science Inventory

There are challenges associated with performing research on titanium dioxide NPs in aquatic environments particularly marine systems. A critical focus for current titanium dioxide NP research in aquatic environments needs to be on optimizing methods for differentiating naturally...

Molecular and physiological responses to titanium dioxide and cerium oxide nanoparticles in Arabidopsis

EPA Science Inventory

- Changes in tissue transcriptomes and productivity of Arabidopsis thaliana were investigated during exposure of plants to two widely-used engineered metal oxide nanoparticles, titanium dioxide (nano-titanium) and cerium dioxide (nano-cerium). Microarray analyses confirmed that e...

Titanium dioxide in fuel cell technology: An overview

NASA Astrophysics Data System (ADS)

Abdullah, N.; Kamarudin, S. K.

2015-03-01

Fuel cell technology is one of the alternative energy sources for the next generation. Although this technology has proven to be one of the main methods for producing new energy sources, fuel cell technology still has some problems that hinder fuel cell commercialization. Recently, new ideas on titanium dioxide are introduced as potential solution in several applications in fuel cell technology. Thus, this article presents an overview on the applications of titanium dioxide and highlights the unique properties and benefits of titanium dioxide in fuel cell technology.

40 CFR 415.226 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2014 CFR

2014-07-01

...) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Titanium Dioxide... CFR 403.7, any new source subject to this subpart and producing titanium dioxide by the sulfate... and achieve the following pretreatment standards for new sources (PSNS): Subpart V—Titanium Dioxide...

40 CFR 415.226 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2011 CFR

2011-07-01

...) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Titanium Dioxide... CFR 403.7, any new source subject to this subpart and producing titanium dioxide by the sulfate... and achieve the following pretreatment standards for new sources (PSNS): Subpart V—Titanium Dioxide...

40 CFR 415.226 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2012 CFR

2012-07-01

...) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Titanium Dioxide... CFR 403.7, any new source subject to this subpart and producing titanium dioxide by the sulfate... and achieve the following pretreatment standards for new sources (PSNS): Subpart V—Titanium Dioxide...

40 CFR 415.226 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2010 CFR

2010-07-01

...) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Titanium Dioxide... CFR 403.7, any new source subject to this subpart and producing titanium dioxide by the sulfate... and achieve the following pretreatment standards for new sources (PSNS): Subpart V—Titanium Dioxide...

Ozonation of return activated sludge for disintegration and solubilisation with synthesized titanium oxide as catalyst

NASA Astrophysics Data System (ADS)

Sarif, S. F. Z. Mohd; Alias, S. S.; Ridwan, F. Muhammad; Salim, K. S. Ku; Abidin, C. Z. A.; Ali, U. F. Md.

2018-03-01

Ozonation of activated sludge in the present of titanium dioxide (TiO2) as catalyst to enhance the production of hydroxyl radical was evaluated in comparison to the sole ozonation process. In this process, the catalytic ozontion showed improvement in increasing ozone consumption and improving activated sludge disintegration and solubilisation. The reduction of total suspended solid (TSS), volatile suspended solid (VSS) and soluble chemical oxygen demand (SCOD) solubilisation was better in the catalytic ozonation system. Initial pH 7 of activated sludge was found best to disintegrate and solubilise the sludge flocs. However upon additional of sodium hydroxide (NaOH) in pH adjustment enhanced the solubilisation of organic matter from the flocs and cells, making the initial pH 9 is the best condition for activated sludge solubilisation. Yet the initial pH 7 of activated sludge supernatant was the best condition to achieve SCOD solubilisation due to sludge floc disintegration, when it had stronger correlation between TSS reduction and SCOD solubilisation (R2=0.961). Lower amount of catalyst of 100 mgTiO2/gTSS was found to disintegrate and solubilise the activated sludge better with 30.4% TSS reduction and 25.2% SCOD solubilisation efficiency, compared to 200 mgTiO2/gTSS with 21.9% and 17.1% TSS reduction and SCOD solubilisation, respectively.

Enhancement of photocatalytic degradation of furfural and acetophenone in water media using nano-TiO2-SiO2 deposited on cementitious materials.

PubMed

Soltan, Sahar; Jafari, Hoda; Afshar, Shahrara; Zabihi, Omid

2016-10-01

In the present study, silicon dioxide (SiO 2 ) nanoparticles were loaded to titanium dioxide (TiO 2 ) nano-particles by sol-gel method to make a high porosity photocatalyst nano-hybrid. These photocatalysts were synthesized using titanium tetrachloride and tetraethyl orthosilicate as titanium and silicon sources, respectively, and characterized by X-ray powder diffraction (XRD) and scanning electron microscope methods. Subsequently, the optimizations of the component and operation conditions were investigated. Then, nano-sized TiO 2 and TiO 2 -SiO 2 were supported on concrete bricks by the dip coating process. The photocatalytic activity of nano photocatalysts under UV irradiation was examined by studying the decomposition of aqueous solutions of furfural and acetophenone (10 mg/L) as model of organic pollutants to CO 2 and H 2 O at room temperature. A decrease in the concentration of these pollutants was assayed by using UV-visible absorption, gas chromatography technique, and chemical oxygen demand. The removal of these pollutants from water using the concrete-supported photocatalysts under UV irradiation was performed with a greater efficiency, which does not require an additional separation stage to recover the catalyst. Therefore, it would be applicable to use in industrial wastewater treatment at room temperature and atmospheric pressure within the optimized pH range.

Degradation of volatile organic compounds in the gas phase by heterogeneous photocatalysis with titanium dioxide/ultraviolet light.

PubMed

Rochetto, Ursula Luana; Tomaz, Edson

2015-07-01

This work presents an overview over heterogeneous photocatalysis performed in gas phase towards the degradation of o-xylene, n-hexane, n-octane, n-decane, methylcyclohexane and 2,2,4-trimethylpentane. The experimental set-up composed by a titanium plug flow reactor vessel contained a quartz tube with a 100 W UV lamp placed at center position from 1.7 cm to the quartz wall. A titanium dioxide film was immobilized on the internal walls of the reactor and used as catalyst. All measurements were taken after reaching steady state condition and evaluated at the inlet and outlet of the system. Conversion rates were studied in a wide range of residence times yielding to a 90% or above conversion as from 20 seconds of residence time. During experiments the temperature of reactor's wall was monitored and remained between 52 and 62 °C. Temperature influence over degradation rates was negligible once a control experiment performed at 15 °C did not modify outgoing results. Humidity effect was also evaluated showing an ideal working range of 10-80% with abrupt conversion decay outside the range. By varying inlet concentration between 60 and 110 ppmv the VOC degradation curves remained unchanged. Loss over catalytic activity was only observed for o-xylene after 30 minutes of reaction, the catalyst was reactivated with a solution of hydrogen peroxide and UV light followed by additional deposition of the catalytic layer. The kinetic study suggests a first order reaction rate. The study of effective and economically viable techniques on the treatment of volatile organic compounds (VOCs) has being highlighted as an important parameter on the environmental research. The heterogeneous photocatalysis in gas phase was proved to be an effective process for the degradation of the nonaromatic VOCs tested, yielding high conversion values for the optimized systems.

Preparation of Heat Treated Titanium Dioxide (TiO2) Nanoparticles for Water Purification

NASA Astrophysics Data System (ADS)

Araoyinbo, A. O.; Abdullah, M. M. A. B.; Rahmat, A.; Azmi, A. I.; Vizureanu, P.; Rahim, W. M. F. Wan Abd

2018-06-01

Photocatalysis using the semiconductor titanium dioxide (TiO2) has proven to be a successful technology for waste water purification. The photocatalytic treatment is an alternative method for the removal of soluble organic compounds in waste water. In this research, titanium dioxide nanoparticles were synthesized by sol-gel method using titanium tetraisopropoxide (TTIP) as a precursor. The sol was dried in the oven at 120°C after aging for 24 hours. The dried powder was then calcined at 400°C and 700°C with a heating rate of 10°C/min. The phase transformation of the heat treated titanium dioxide nanoparticles were characterized by X-Ray Diffraction (XRD, and the surface morphology by Scanning Electron Microscopy (SEM). The photocatalytic activity of the heat treated titanium dioxide nanoparticles in the degradation of methyl orange (MO) dye under ultraviolet (UV) light irradiation has been studied. At calcination temperature of 400°C, only anatase phase was observed, as the calcination temperature increases to 700°C, the rutile phase was present. The SEM images show the irregular shape of titanium dioxide particles and the agglomeration which tends to be more significant at calcined temperature of 700°C. Degradation of methyl orange by 5 mg heat treated titanium dioxide nanoparticles gives the highest percentage of degradation after irradiation by UV lamp for 4 hours.

21 CFR 73.2575 - Titanium dioxide.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR.... The color additive titanium dioxide shall conform in identity and specifications to the requirements...

21 CFR 73.3126 - Titanium dioxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891, shall...

21 CFR 73.3126 - Titanium dioxide.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891, shall...

21 CFR 73.3126 - Titanium dioxide.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891, shall...

21 CFR 73.3126 - Titanium dioxide.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891, shall...

21 CFR 73.3126 - Titanium dioxide.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891, shall...

40 CFR 415.222 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2011 CFR

2011-07-01

... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.222 Effluent limitations guidelines... point source subject to this subpart and producing titanium dioxide by the sulfate process must achieve... application of the best practicable control technology currently available (BPT): Subpart V—Titanium Dioxide...

40 CFR 415.222 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2010 CFR

2010-07-01

... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.222 Effluent limitations guidelines... point source subject to this subpart and producing titanium dioxide by the sulfate process must achieve... application of the best practicable control technology currently available (BPT): Subpart V—Titanium Dioxide...

40 CFR 415.223 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2014 CFR

2014-07-01

... CATEGORY Titanium Dioxide Production Subcategory § 415.223 Effluent limitations guidelines representing the... to this subpart and producing titanium dioxide by the sulfate process must achieve the following..., any existing point source subject to this subpart and producing titanium dioxide by the chloride...

40 CFR 415.222 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2014 CFR

2014-07-01

... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.222 Effluent limitations guidelines... point source subject to this subpart and producing titanium dioxide by the sulfate process must achieve... application of the best practicable control technology currently available (BPT): Subpart V—Titanium Dioxide...

40 CFR 415.222 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2013 CFR

2013-07-01

... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.222 Effluent limitations guidelines... point source subject to this subpart and producing titanium dioxide by the sulfate process must achieve... application of the best practicable control technology currently available (BPT): Subpart V—Titanium Dioxide...

40 CFR 415.222 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2012 CFR

2012-07-01

... SOURCE CATEGORY Titanium Dioxide Production Subcategory § 415.222 Effluent limitations guidelines... point source subject to this subpart and producing titanium dioxide by the sulfate process must achieve... application of the best practicable control technology currently available (BPT): Subpart V—Titanium Dioxide...

40 CFR 415.223 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2013 CFR

2013-07-01

... CATEGORY Titanium Dioxide Production Subcategory § 415.223 Effluent limitations guidelines representing the... to this subpart and producing titanium dioxide by the sulfate process must achieve the following..., any existing point source subject to this subpart and producing titanium dioxide by the chloride...

Titanium dioxide in dental enamel as a trace element and its variation with bleaching

PubMed Central

Durán-Sedó, Randall; Herrera-Sancho, Óscar-Andrey

2018-01-01

Background Titanium is a less studied trace element in dental enamel. Literature relates an increased Titanium concentration with a decreased enamel crystal domain size, which in turn is related to a higher color value. The aim of our study was to analyze the effect of tooth bleaching agents on its concentration in dental enamel by means of confocal Raman spectroscopy. Material and Methods Human teeth were randomly distributed in six experimental groups (n=10) and submitted to different bleaching protocols according to the manufacturer´s instructions. Confocal Raman spectroscopy was carried out in order to identify and quantify the presence of titanium dioxide molecules in enamel prior to and during whitening. Statistical analysis included repeated measures analysis of variance (p≤0.05) and Bonferroni pairwise comparisons. Results Titanium dioxide concentration was negatively affected by the longer bleaching protocols (at-home bleaching gels). All in-office whitening products increased significantly the studied molecule (p≤0,05). Conclusions All dental specimens depicted the presence of titanium dioxide as a trace element in dental enamel. Bleaching gels that have to be applied at higher concentrations but for shorter periods of time increase the concentration of titanium dioxide, whilst at-home whitening gels used for longer periods of time despite the lower concentration caused a loss in titanium. Key words:Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, titanium dioxide. PMID:29930771

Titanium dioxide in dental enamel as a trace element and its variation with bleaching.

PubMed

Vargas-Koudriavtsev, Tatiana; Durán-Sedó, Randall; Herrera-Sancho, Óscar-Andrey

2018-06-01

Titanium is a less studied trace element in dental enamel. Literature relates an increased Titanium concentration with a decreased enamel crystal domain size, which in turn is related to a higher color value. The aim of our study was to analyze the effect of tooth bleaching agents on its concentration in dental enamel by means of confocal Raman spectroscopy. Human teeth were randomly distributed in six experimental groups (n=10) and submitted to different bleaching protocols according to the manufacturer´s instructions. Confocal Raman spectroscopy was carried out in order to identify and quantify the presence of titanium dioxide molecules in enamel prior to and during whitening. Statistical analysis included repeated measures analysis of variance ( p ≤0.05) and Bonferroni pairwise comparisons. Titanium dioxide concentration was negatively affected by the longer bleaching protocols (at-home bleaching gels). All in-office whitening products increased significantly the studied molecule ( p ≤0,05). All dental specimens depicted the presence of titanium dioxide as a trace element in dental enamel. Bleaching gels that have to be applied at higher concentrations but for shorter periods of time increase the concentration of titanium dioxide, whilst at-home whitening gels used for longer periods of time despite the lower concentration caused a loss in titanium. Key words: Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, titanium dioxide.

Investigation of polypyrrole/polyvinyl alcohol-titanium dioxide composite films for photo-catalytic applications

NASA Astrophysics Data System (ADS)

Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long; Dan, Yi

2015-07-01

Polypyrrole/polyvinyl alcohol-titanium dioxide (PPy/PVA-TiO2) composite films used as photo-catalysts were fabricated by combining TiO2 sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO2 and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet-vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA-TiO2 composite films show better photo-catalytic properties than TiO2 film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA-TiO2 composite film was investigated and the results show that the photo-catalytic activity under both UV and visible light irradiation have no significant decrease after four times of recycle experiments, suggesting that the photo-catalyst film is stable during the photo-catalytic process, which was also confirmed by the XRD pattern and FT-IR spectra of the composite film before and after photo-catalytic.

Novel strategy to mitigate cathode catalyst degradation during air/air startup cycling via the atmospheric resistive switching mechanism of a hydrogen anode with a platinum catalyst supported on tantalum-doped titanium dioxide

NASA Astrophysics Data System (ADS)

Shintani, Haruhiko; Kojima, Yuya; Kakinuma, Katsuyoshi; Watanabe, Masahiro; Uchida, Makoto

2015-10-01

We propose a new strategy for alleviating the reverse current phenomenon using a unique ;atmospheric resistive switching mechanism; (ARSM) of a metal oxide semiconductor support, such that the electrical resistivity changes depending on the gas atmosphere. The membrane-electrode assembly (MEA) using Ta-doped TiO2-supported platinum (Pt/Ta-TiO2) as the anode catalyst showed approximately one order of magnitude greater resistance in air than in hydrogen. The overpotential of the hydrogen oxidation reaction was negligible up to at least 1.5 A cm-2. The losses of electrochemically active surface area and carbon corrosion of the cathode catalyst during air/air startup cycling were significantly suppressed by the use of the Pt/Ta-TiO2 anode. The decrease in the degradation is attributed to a reduction of the reverse current due to a low oxygen reduction reaction rate at the anode, which showed high resistivity in air. These results demonstrate the effectiveness of the ARSM in mitigating cathode catalyst degradation during air/air startup cycling.

21 CFR 73.575 - Titanium dioxide.

Code of Federal Regulations, 2011 CFR

2011-04-01

... and that are listed in this subpart as safe in color additive mixtures for coloring foods, and the... coloring foods generally, subject to the following restrictions: (1) The quantity of titanium dioxide does... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Titanium dioxide. 73.575 Section 73.575 Food and...

21 CFR 73.575 - Titanium dioxide.

Code of Federal Regulations, 2010 CFR

2010-04-01

... and that are listed in this subpart as safe in color additive mixtures for coloring foods, and the... coloring foods generally, subject to the following restrictions: (1) The quantity of titanium dioxide does... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.575 Section 73.575 Food and...

Photocatalytic degradation of furfural in aqueous solution by N-doped titanium dioxide nanoparticles.

PubMed

Veisi, Farzaneh; Zazouli, Mohammad Ali; Ebrahimzadeh, Mohammad Ali; Charati, Jamshid Yazdani; Dezfoli, Amin Shiralizadeh

2016-11-01

The photocatalytic degradation of furfural in aqueous solution was investigated using N-doped titanium dioxide nanoparticles under sunlight and ultraviolet radiation (N-TiO 2 /Sun and N-TiO 2 /UV) in a lab-scale batch photoreactor. The N-TiO 2 nanoparticles prepared using a sol-gel method were characterized using XRD, X-ray photoelectron spectroscopy (XPS), and SEM analyses. Using HPLC to monitor the furfural concentration, the effect of catalyst dosage, contact time, initial solution pH, initial furfural concentration, and sunlight or ultraviolet radiation on the degradation efficiency was studied. The efficiency of furfural removal was found to increase with increased reaction time, nanoparticle loading, and pH for both processes, whereas the efficiency decreased with increased furfural concentration. The maximum removal efficiencies for the N-TiO 2 /UV and N-TiO 2 /Sun processes were 97 and 78 %, respectively, whereas the mean removal efficiencies were 80.71 ± 2.08 % and 62.85 ± 2.41 %, respectively. In general, the degradation and elimination rate of furfural using the N-TiO 2 /UV process was higher than that using the N-TiO 2 /Sun process.

Photocatalytic removal of polychlorinated biphenyls (PCBs) using carbon-modified titanium oxide nanoparticles

NASA Astrophysics Data System (ADS)

Shaban, Yasser A.; El Sayed, Mohamed A.; El Maradny, Amr A.; Al Farawati, Radwan Kh.; Al Zobidi, Mosa I.; Khan, Shahed U. M.

2016-03-01

In this work, the sonicated sol-gel method was used for synthesizing carbon-modified titanium oxide nanoparticles. Carbon incorporation was achieved by using titanium (IV) isopropoxide as a titanium and carbon-containing precursor. The photocatalytic efficiency of the synthesized photocatalyst was assessed by examining the photocatalytic removal of polychlorinated biphenyls (PCBs) from aqueous solution. For comparison, unmodified (regular) titanium dioxide (n-TiO2) was used as a reference catalyst. To confirm the carbon incorporation in CM-n-TiO2 nanoparticles, energy dispersive spectroscopy (EDS) analysis was used. Significantly, the bandgap energy was found to be reduced from 2.99 eV for n-TiO2 to 1.8 eV for CM-n-TiO2, which in turn improved the performance of CM-n-TiO2 toward the photocatalytic removal of PCBs. The effects of CM-n-TiO2 loading, PCBs concentration, and pH of the solution on the photodegradation rate of PCBs were investigated. The highest removal rate was found to be at pH 5 and CM-n-TiO2 loading of 0.5 g L-1. According to Langmuir-Hinshelwood model, the photodegradation of PCBs using CM-n-TiO2 followed a pseudo-first order reaction kinetics.

Electrochemical response of carbon paste electrode modified with mixture of titanium dioxide/zirconium dioxide in the detection of heavy metals: lead and cadmium.

PubMed

Nguyen, Phuong Khanh Quoc; Lunsford, Suzanne K

2012-11-15

A novel carbon modified electrode was developed by incorporating titanium dioxide/zirconium dioxide into the graphite carbon paste electrode to detect heavy metals-cadmium and lead. In this work, the development of the novel titanium dioxide/zirconium dioxide modified carbon paste electrode was studied to determine the optimum synthesis conditions related to the temperature, heating duration, amount and ratio of titanium dioxide/zirconium dioxide, and amount of surfactant, to create the most reproducible results. Using cyclic voltammetric (CV) analysis, this study has proven that the novel titanium dioxide/zirconium dioxide can be utilized to detect heavy metals-lead and cadmium, at relatively low concentrations (7.6×10(-6) M and 1.1×10(-5) M for Pb and Cd, respectively) at optimum pH value (pH=3). From analyzing CV data the optimal electrodes surface area was estimated to be 0.028 (±0.003) cm(2). Also, under the specific experimental conditions, electron transfer coefficients were estimated to be 0.44 and 0.33 along with the heterogeneous electron transfer rate constants of 5.64×10(-3) and 2.42×10(-3) (cm/s) for Pb and Cd, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Catalysts for the selective oxidation of hydrogen sulfide to sulfur

DOEpatents

Srinivas, Girish; Bai, Chuansheng

2000-08-08

This invention provides catalysts for the oxidation of hydrogen sulfide. In particular, the invention provides catalysts for the partial oxidation of hydrogen sulfide to elemental sulfur and water. The catalytically active component of the catalyst comprises a mixture of metal oxides containing titanium oxide and one or more metal oxides which can be selected from the group of metal oxides or mixtures of metal oxides of transition metals or lanthanide metals. Preferred metal oxides for combination with TiO.sub.2 in the catalysts of this invention include oxides of V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Tc, Ru, Rh, Hf, Ta, W, Au, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Catalysts which comprise a homogeneous mixture of titanium oxide and niobium (Nb) oxide are also provided. A preferred method for preparing the precursor homogenous mixture of metal hydroxides is by coprecipitation of titanium hydroxide with one or more other selected metal hydroxides. Catalysts of this invention have improved activity and/or selectivity for elemental sulfur production. Further improvements of activity and/or selectivity can be obtained by introducing relatively low amounts (up to about 5 mol %)of a promoter metal oxide (preferably of metals other than titanium and that of the selected second metal oxide) into the homogeneous metal/titanium oxide catalysts of this invention.

Heterogeneous Photocatalytic Oxidation of Atmospheric Trace Contaminants

NASA Technical Reports Server (NTRS)

Ollis, David F.

1996-01-01

Heterogeneous photocatalysis involves the use of a light-activated catalyst at room temperature in order to carry out a desired reaction. In the presence of molecular oxygen, illumination of the n-type semiconductor oxide titanium dioxide (TiO2) provides for production of highly active forms of oxygen, such as hydroxyl radicals, which are able to carry out the complete oxidative destruction of simple hydrocarbons such as methane, ethane, ethylene, propylene, and carbon monoxide. This broad oxidation potential, coupled with the ability with sufficient residence time to achieve complete oxidation of simple hydrocarbon contaminants to carbon dioxide and water, indicated that heterogeneous photocatalysis should be examined for its potential for purification of spacecraft air. If a successful catalyst and photoreactor could be demonstrated at the laboratory level, such results would allow consideration of photocatalysts as a partial or complete replacement of adsorption systems, thereby allowing for reduction in lift-off weight of a portion of the life support system for the spacecraft, or other related application such as a space station or a conventional commercial aircraft. The present research was undertaken to explore this potential through achievement of the following plan of work: (a) ascertain the intrinsic kinetics of conversion of pollutants of interest in spacecraft, (b) ascertain the expected lifetime of catalysts through examination of most likely routes of catalyst deactivation and regeneration, (c) model and explore experimentally the low pressure drop catalytic monolith, a commercial configuration for automotive exhaust control, and (d) examine the kinetics of multicomponent conversions. In the recent course of this work, we have also discovered how to increase catalyst activity via halide promotion which has allowed us to achieve approximately 100% conversion of an aromatic contaminant (toluene) in a very short residence time of 5-6 milliseconds.

Heterogeneous Photocatalytic Oxidation of Atmospheric Trace Contaminants

NASA Technical Reports Server (NTRS)

Ollis, David F.

1996-01-01

Heterogeneous photocatalysis involves the use of a light-activated catalyst at room temperature in order to carry out a desired reaction. In the presence of molecular oxygen, illumination of the n-type semiconductor oxide titanium dioxide (TiO2) provides for production of highly active forms of oxygen, such as hydroxyl radicals, which are able to carry out the complete oxidative destruction of simple hydrocarbons such as methane, ethane, ethylene, propylene, and carbon monoxide. This broad oxidation potential, coupled with the ability with sufficient residence time to achieve complete oxidation of simple hydrocarbon contaminants to carbon dioxide and water, indicated that heterogeneous photocatalysis should be examined for its potential for purification of spacecraft air. If a successful catalyst and photoreactor could be demonstrated at the laboratory level, such results would allow consideration of photocatalysts as a partial or complete replacement of adsorption systems, thereby allowing for reduction in lift-off weight of a portion of the life support system for the spacecraft, or other related application such as a space station or a conventional commercial aircraft. The present research was undertaken to explore this potential through achievement of the following plan of work: (a) ascertain the intrinsic kinetics of conversion of pollutants of interest in spacecraft, (b) ascertain the expected lifetime of catalysts through examination of most likely routes of catalyst deactivation and regeneration (c) model and explore experimentally the low pressure drop catalytic monolith, a commercial configuration for automotive exhaust control (d) examine the kinetics of multicomponent conversions. In the recent course of this work, we have also discovered how to increase catalyst activity via halide promotion which has allowed us to achieve approximately 100% conversion of an aromatic contaminant (toluene) in a very short residence time of 5-6 milliseconds.

The photocatalytic and cytotoxic effects of titanium dioxide particles used in sunscreen

NASA Astrophysics Data System (ADS)

Rampaul, Ashti

Titanium dioxide nanoparticles are used in sunscreens to reflect UV radiation from the skin. However, titanium dioxide as anatase and rutile crystal forms is a well-known photocatalyst. The nanoparticles are surface coated with inert inorganic oxides such as silica and alumina or organics such as organosilanes or silicone polymers and more recently, have been doped with manganese oxide. These modifications to the titanium dioxide particles are purported to prevent the production of harmful reactive oxygen species. A range of sunscreens was tested with crystal form and modification type identified via XRD, Raman Spectroscopy, XPS and SSNMR. The particle modification and crystal form determined whether the particles were inert or rapidly degraded methylene blue dye, and killed or protected cultured human epithelium cells. Novel solid state Electron Paramagnetic Resonance analysis showed that the greatest amount of superoxide anions was formed during UVA irradiation of the mixed anatase and rutile crystal forms coated with an organosilane. These particles also degraded methylene blue at a similar rate to Degussa P25, a standard uncoated titanium dioxide powder and produced an increase in UVA induced apoptosis of human keratinocytes. Double Stranded Breaks were observed extensively in cells exposed to UVA irradiated mixed anatase and rutile titanium dioxide with organosilane. A new apoptotic-like cell death mechanism may have been recognised during the UVA irradiation of animal and human cells in the presence of titanium dioxide. This research concludes that mixed anatase and rutile crystal forms of titanium dioxide coated with organosilane or dimethicone may not be safe to use in sunscreen lotions. A less harmful alternative for sunscreen formulations is the manganese doped rutile particles or the alumina coated rutile powders, both of which exhibited a protective effect on cultured epithelial cells.

Facile hydrothermal preparation of titanium dioxide decorated reduced graphene oxide nanocomposite

PubMed Central

Chang, Betty Yea Sze; Huang, Nay Ming; An’amt, Mohd Nor; Marlinda, Abdul Rahman; Norazriena, Yusoff; Muhamad, Muhamad Rasat; Harrison, Ian; Lim, Hong Ngee; Chia, Chin Hua

2012-01-01

A simple single-stage approach, based on the hydrothermal technique, has been introduced to synthesize reduced graphene oxide/titanium dioxide nanocomposites. The titanium dioxide nanoparticles are formed at the same time as the graphene oxide is reduced to graphene. The triethanolamine used in the process has two roles. It acts as a reducing agent for the graphene oxide as well as a capping agent, allowing the formation of titanium dioxide nanoparticles with a narrow size distribution (~20 nm). Transmission electron micrographs show that the nanoparticles are uniformly distributed on the reduced graphene oxide nanosheet. Thermogravimetric analysis shows the nanocomposites have an enhanced thermal stability over the original components. The potential applications for this technology were demonstrated by the use of a reduced graphene oxide/titanium dioxide nanocomposite-modified glassy carbon electrode, which enhanced the electrochemical performance compared to a conventional glassy carbon electrode when interacting with mercury(II) ions in potassium chloride electrolyte. PMID:22848166

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Yu, E-mail: xieyu_121@163.com; Key Laboratory of Photochemical Conversion and Optoelectronic Materials, TIPC, CAS, Beijing 100190; Hong, Xiaowei

Graphical abstract: Due to combining different functions and characteristics of individual materials, hybrid nanocomposite materials can strengthen their applications. Magnetic-conductive nanocomposites are the promising materials with electromagnetic loss, which have synergetic behavior between magnetic and conductive materials. It is the first time to report the synthesis of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide (BF/TD) composites by the gel-precursor self-propagating combustion process. The influence of mass ratio of BF and TD on the electromagnetic properties of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites was studied. The tgδ{sub μ} and tgδ{sub ε} of BF–TD composites. - Highlights: • It is the first time tomore » report BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites. • The composites are prepared by the gel-precursor self-propagating combustion. • The electromagnetic properties could be adjusted by the mass ratio of BF and TD. • The introduction of TD enhances the dielectric loss and widens the frequency bands. • BF/TD composites will be microwave absorption materials with wide frequency band. - Abstract: Doped BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites have been prepared by the gel-precursor self-propagating combustion process. The characterization of the composites are performed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Differential thermal analysis-thermo gravimetry (DTA–TG), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and network analyzer. Both XRD and FT-IR indicate that the doped BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites are successfully synthesized and there are some interactions between BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19} and titanium dioxide. DTA–TG analysis of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites shows that the composite gel decomposition process mainly includes two stages: the first stage is the crystallized water and the residual moisture evaporation; the second stage is the nitrate and citric acid decomposition reaction. SEM demonstrates that the doped BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide solid solution has formed. The magnetic parameters indicate that the electromagnetic properties of the composites could be well adjusted by the mass ratio of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19} and titanium dioxide. When the mass ratio of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19} and titanium dioxide is 4:5, the composites have the best magnetic loss. The composites with the mass ratio 6:5 of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19} and titanium dioxide. BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19} and titanium dioxide possess good dielectric loss. The introduction of titanium dioxide enhances the dielectric loss and widens the frequency bands. The composites will be promising microwave absorption materials with wide frequency band.« less

Silica-supported, single-site titanium catalysts for olefin epoxidation. A molecular precursor strategy for control of catalyst structure.

PubMed

Jarupatrakorn, Jonggol; Don Tilley, T

2002-07-17

A molecular precursor approach involving simple grafting procedures was used to produce site-isolated titanium-supported epoxidation catalysts of high activity and selectivity. The tris(tert-butoxy)siloxy titanium complexes Ti[OSi(O(t)Bu)(3)](4) (TiSi4), ((i)PrO)Ti[OSi(O(t)Bu)(3)](3) (TiSi3), and ((t)BuO)(3)TiOSi(O(t)Bu)(3) (TiSi) react with the hydroxyl groups of amorphous Aerosil, mesoporous MCM-41, and SBA-15 via loss of HO(t)Bu and/or HOSi(O(t)Bu)(3) and introduction of titanium species onto the silica surface. Powder X-ray diffraction, nitrogen adsorption/desorption, infrared, and diffuse reflectance ultraviolet spectroscopies were used to investigate the structures and chemical natures of the surface-bound titanium species. The titanium species exist mainly in isolated, tetrahedral coordination environments. Increasing the number of siloxide ligands in the molecular precursor decreases the amount of titanium that can be introduced this way, but also enhances the catalytic activity and selectivity for the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. In addition, the high surface area mesoporous silicas (MCM-41 and SBA-15) are more effective than amorphous silica as supports for these catalysts. Supporting TiSi3 on the SBA-15 affords highly active cyclohexene epoxidation catalysts (0.25-1.77 wt % Ti loading) that provide turnover frequencies (TOFs) of 500-1500 h(-1) after 1 h (TOFs are reduced by about half after calcination). These results demonstrate that oxygen-rich siloxide complexes of titanium are useful as precursors to supported epoxidation catalysts.

Nanostructures having crystalline and amorphous phases

DOEpatents

Mao, Samuel S; Chen, Xiaobo

2015-04-28

The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

Determination and identification of titanium dioxide nanoparticles in confectionery foods, marketed in South Korea, using inductively coupled plasma optical emission spectrometry and transmission electron microscopy.

PubMed

Kim, Namhoon; Kim, Changkyu; Jung, Soyoung; Park, Youngae; Lee, Youngju; Jo, Juyeon; Hong, Misun; Lee, Sangmi; Oh, Younghee; Jung, Kweon

2018-06-18

Food-grade titanium dioxide (TiO 2 ) is a common and widespread food additive in many processed foods, personal care products, and other industrial categories as it boosts the brightness and whiteness of colours. Although it is generally recognised as safe for humans, there is a growing interest in the health risks associated with its oral intake. This study quantified and identified TiO 2 nanoparticles present in confectionery foods, which are children's favourite foods, with inductively coupled plasma optical emission spectrometry (ICP-OES) and transmission electron microscopy (TEM). A reliable digestion method using hot sulphuric acid and a digestion catalyst (K 2 SO 4 :CuSO 4  = 9:1) was suggested for titanium analysis. Validations of the experimental method were quite acceptable in terms of linearity, recoveries, detection limits, and quantification limits. Of all the 88 analysed foods, TiO 2 was detected in 19 products, all except three declared TiO 2 in their labelling. The mean TiO 2 content of candies, chewing gums, and chocolates were 0.36 mg g -1 , 0.04 mg g -1 , and 0.81 mg g -1 , respectively. Whitish particles isolated from the confectionery foods were confirmed as TiO 2 nanoparticles via TEM and energy dispersive X-ray spectroscopy (EDX), in which nanosized particles (<100 nm) were identified.

Direct dynamic synthesis of nanodispersed phases of titanium oxides upon sputtering of electrodischarge titanium plasma into an air atmosphere

NASA Astrophysics Data System (ADS)

Sivkov, A. A.; Gerasimov, D. Yu.; Nikitin, D. S.

2017-01-01

Experimental investigations of the possibility of directly synthesizing nanodispersed crystalline phases of titanium dioxides with rutile and anatase structures in a hypervelocity jet of electroerosion plasma generated by a coaxial magnetoplasma accelerator with titanium electrodes are presented. A powder product containing nanosized polymorphic phases of titanium dioxide with a spherical shape of particles has been manufactured.

Titanium pigmentation. An electron probe microanalysis study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dupre, A.; Touron, P.; Daste, J.

1985-05-01

A patient had an unusual pigmentary disease induced by titanium dioxide. The use of a topical cream containing titanium dioxide caused a xanthomalike appearance on the patient's penis. Electron probe microanalysis was valuable in establishing the cause of this balanitis.

Carbon dioxide-soluble polymers and swellable polymers for carbon dioxide applications

DOEpatents

DeSimone, Joseph M.; Birnbaum, Eva; Carbonell, Ruben G.; Crette, Stephanie; McClain, James B.; McCleskey, T. Mark; Powell, Kimberly R.; Romack, Timothy J.; Tumas, William

2004-06-08

A method for carrying out a catalysis reaction in carbon dioxide comprising contacting a fluid mixture with a catalyst bound to a polymer, the fluid mixture comprising at least one reactant and carbon dioxide, wherein the reactant interacts with the catalyst to form a reaction product. A composition of matter comprises carbon dioxide and a polymer and a reactant present in the carbon dioxide. The polymer has bound thereto a catalyst at a plurality of chains along the length of the polymer, and wherein the reactant interacts with the catalyst to form a reaction product.

Effect and interaction study of acetamiprid photodegradation using experimental design.

PubMed

Tassalit, Djilali; Chekir, Nadia; Benhabiles, Ouassila; Mouzaoui, Oussama; Mahidine, Sarah; Merzouk, Nachida Kasbadji; Bentahar, Fatiha; Khalil, Abbas

2016-10-01

The methodology of experimental research was carried out using the MODDE 6.0 software to study the acetamiprid photodegradation depending on the operating parameters, such as the initial concentration of acetamiprid, concentration and type of the used catalyst and the initial pH of the medium. The results showed the importance of the pollutant concentration effect on the acetamiprid degradation rate. On the other hand, the amount and type of the used catalyst have a considerable influence on the elimination kinetics of this pollutant. The degradation of acetamiprid as an environmental pesticide pollutant via UV irradiation in the presence of titanium dioxide was assessed and optimized using response surface methodology with a D-optimal design. The acetamiprid degradation ratio was found to be sensitive to the different studied factors. The maximum value of discoloration under the optimum operating conditions was determined to be 99% after 300 min of UV irradiation.

Non-metal doped TiO2 nanotube arrays for high efficiency photocatalytic decomposition of organic species in water

NASA Astrophysics Data System (ADS)

Szkoda, Mariusz; Siuzdak, Katarzyna; Lisowska-Oleksiak, Anna

2016-10-01

Titanium dioxide is a well-known photoactive semiconductor with a variety of possible applications. The procedure of pollutant degradation is mainly performed using TiO2 powder suspension. It can also be exploited an immobilized catalyst on a solid support. Morphology and chemical doping have a great influence on TiO2 activity under illumination. Here we compare photoactivity of titania nanotube arrays doped with non-metal atoms: nitrogen, iodine and boron applied for photodegradation of organic dye - methylene blue and terephtalic acid. The doped samples act as a much better photocatalyst in the degradation process of methylene blue and lead to the formation of much higher amount of hydroxyl radicals (•OH) than undoped TiO2 nanotube arrays. The use of a catalyst active under solar light illumination in the form of thin films on a stable substrate can be scaled up for an industrial application.

A H2-evolving photocathode based on direct sensitization of MoS3 with an organic photovoltaic cell

PubMed Central

Bourgeteau, Tiphaine; Tondelier, Denis; Geffroy, Bernard; Brisse, Romain; Laberty-Robert, Christel; Campidelli, Stéphane; de Bettignies, Rémi; Artero, Vincent; Palacin, Serge; Jousselme, Bruno

2013-01-01

An organic solar cell based on a poly-3-hexylthiophene (P3HT): phenyl-C61-butyric acid (PCBM) bulk hetero-junction was directly coupled with molybdenum sulfide resulting in the design of a new type of photocathode for the production of hydrogen. Both the light-harvesting system and the catalyst were deposited by low-cost solution-processed methods, i.e. spin coating and spray coating respectively. Spray-coated MoS3 films are catalytically active in strongly acidic aqueous solutions with the best efficiencies for thicknesses of 40 to 90 nm. The photocathodes display photocurrents higher than reference samples, without catalyst or without coupling with a solar cell. Analysis by gas chromatography confirms the light-induced hydrogen evolution. The addition of titanium dioxide in the MoS3 film enhances electron transport and collection within thick films and therefore the performance of the photocathode. PMID:24404434

An investigation of adhesive/adherend and fiber/matrix interactions. Part A: Surface characterization of titanium dioxide, titantium and titanium 6% Al to 4% V powders: Interaction with water, hydrogen chloride and polymers

NASA Technical Reports Server (NTRS)

Siriwardane, R. V.; Wightman, J. P.

1982-01-01

The titanium dioxide surface is discussed. Polymer adhesive are also discussed. Titanium powders are considered. Characterization techniques are also considered. Interactions with polymers, water vapor, and HCl are reported. Adsorbents are characterized.

Modularized and water-cooled photo-catalyst cleaning devices for aquaponics based on ultraviolet light-emitting diodes

NASA Astrophysics Data System (ADS)

Yang, Henglong; Lung, Louis; Wei, Yu-Chien; Huang, Yi-Bo; Chen, Zi-Yu; Chou, Yu-Yang; Lin, Anne-Chin

2017-08-01

The feasibility of applying ultraviolet light-emitting diodes (UV-LED's) as triggering sources of photo-catalyst based on titanium dioxide (TiO2) nano-coating specifically for water-cleaning process in an aquaponics system was designed and proposed. The aquaponics system is a modern farming system to integrate aquaculture and hydroponics into a single system to establish an environmental-friendly and lower-cost method for farming fish and vegetable all together in urban area. Water treatment in an aquaponics system is crucial to avoid mutual contamination. we proposed a modularized watercleaning device composed of all commercially available components and parts to eliminate organic contaminants by using UV-LED's for TiO2 photo-catalyst reaction. This water-cleaning module consisted of two coaxial hollowed cylindrical pipes can be submerged completely in water for water treatment and cooling UV-LED's. The temperature of the UV-LED after proper thermal management can be reduced about 16% to maintain the optimal operation condition. Our preliminary experimental result by using Methylene Blue solution to simulate organic contaminants indicated that TiO2 photo-catalyst triggered by UV-LED's can effectively decompose organic compound and decolor Methylene Blue solution.

Effect of the nanosized TiO2 particles in Pd/C catalysts as cathode materials in direct methanol fuel cells.

PubMed

Choi, Mahnsoo; Han, Choonsoo; Kim, In-Tae; Lee, Ji-Jung; Lee, Hong-Ki; Shim, Joongpyo

2011-07-01

Pd-TiO2/C catalysts were prepared by impregnating titanium dioxide (TiO2) on carbon-supported Pd (Pd/C) for use as the catalyst for the oxygen reduction reaction (ORR) in direct methanol fuel cells (DMFCs). Transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were carried to confirm the distribution, morphology and structure of Pd and TiO2 on the carbon support. In fuel cell test, we confirmed that the addition of TiO2 nanoparticles make the improved catalytic activity of oxygen reduction. The electrochemical characterization of the Pd-TiO2/C catalyst for the ORR was carried out by cyclic voltammetry (CV) in the voltage window of 0.04 V to 1.2 V with scan rate of 25 mV/s. With the increase in the crystallite size of TiO2, the peak potential for OH(ads) desorption on the surface of Pd particle shifted to higher potential. This implies that TiO2 might affect the adsorption and desorption of oxygen molecules on Pd catalyst. The performance of Pd-TiO2/C as a cathode material was found to be similar to or better performance than that of Pt/C.

Novel Antimicrobial Titanium Dioxide Nanotubes Obtained through a Combination of Atomic Layer Deposition and Electrospinning Technologies.

PubMed

López de Dicastillo, Carol; Patiño, Cristian; Galotto, María Jose; Palma, Juan Luis; Alburquenque, Daniela; Escrig, Juan

2018-02-24

The search for new antimicrobial substances has increased in recent years. Antimicrobial nanostructures are one of the most promising alternatives. In this work, titanium dioxide nanotubes were obtained by an atomic layer deposition (ALD) process over electrospun polyvinyl alcohol nanofibers (PVN) at different temperatures with the purpose of obtaining antimicrobial nanostructures with a high specific area. Electrospinning and ALD parameters were studied in order to obtain PVN with smallest diameter and highest deposition rate, respectively. Chamber temperature was a key factor during ALD process and an appropriate titanium dioxide deposition performance was achieved at 200 °C. Subsequently, thermal and morphological analysis by SEM and TEM microscopies revealed hollow nanotubes were obtained after calcination process at 600 °C. This temperature allowed complete polymer removal and influenced the resulting anatase crystallographic structure of titanium dioxide that positively affected their antimicrobial activities. X-ray analysis confirmed the change of titanium dioxide crystallographic structure from amorphous phase of deposited PVN to anatase crystalline structure of nanotubes. These new nanostructures with very large surface areas resulted in interesting antimicrobial properties against Gram-positive and Gram-negative bacteria. Titanium dioxide nanotubes presented the highest activity against Escherichia coli with 5 log cycles reduction at 200 μg/mL concentration.

Temperature dependence and P/Ti ratio in phosphoric acid treatment of titanium dioxide and powder properties.

PubMed

Onoda, H; Matsukura, A

2015-02-01

Titanium dioxide has photocatalytic activity and is used as a white pigment for cosmetics. A certain degree of sebum on the skin is decomposed by the ultraviolet radiation in sunlight. In this work, titanium dioxide was shaken with phosphoric acid to synthesize a white pigment for cosmetics. Titanium dioxide was treated with 0.1 mol/L of phosphoric acid at various P/Ti molar ratios, and then shaken in hot water for 1 h. The chemical composition, powder properties, photocatalytic activity, colour phase, and smoothness of the obtained powder were studied. The obtained materials indicated XRD peaks of titanium dioxide, however the peaks diminished subsequent to phosphoric acid treatment. The samples included small particles with sub-micrometer size. The photocatalytic activity of the obtained powders decreased, decomposing less sebum on the skin. Samples prepared at high P/Ti ratio with high shaking temperature indicated low whiteness in in L*a*b* colour space. The shaking and heating temperature and P/Ti ratio had influence on the smoothness of the obtained materials. Phosphoric acid treatment of titanium dioxide is an effective method to inhibit photocatalytic activity for a white pigment. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Novel Antimicrobial Titanium Dioxide Nanotubes Obtained through a Combination of Atomic Layer Deposition and Electrospinning Technologies

PubMed Central

Patiño, Cristian; Galotto, María Jose; Palma, Juan Luis; Alburquenque, Daniela

2018-01-01

The search for new antimicrobial substances has increased in recent years. Antimicrobial nanostructures are one of the most promising alternatives. In this work, titanium dioxide nanotubes were obtained by an atomic layer deposition (ALD) process over electrospun polyvinyl alcohol nanofibers (PVN) at different temperatures with the purpose of obtaining antimicrobial nanostructures with a high specific area. Electrospinning and ALD parameters were studied in order to obtain PVN with smallest diameter and highest deposition rate, respectively. Chamber temperature was a key factor during ALD process and an appropriate titanium dioxide deposition performance was achieved at 200 °C. Subsequently, thermal and morphological analysis by SEM and TEM microscopies revealed hollow nanotubes were obtained after calcination process at 600 °C. This temperature allowed complete polymer removal and influenced the resulting anatase crystallographic structure of titanium dioxide that positively affected their antimicrobial activities. X-ray analysis confirmed the change of titanium dioxide crystallographic structure from amorphous phase of deposited PVN to anatase crystalline structure of nanotubes. These new nanostructures with very large surface areas resulted in interesting antimicrobial properties against Gram-positive and Gram-negative bacteria. Titanium dioxide nanotubes presented the highest activity against Escherichia coli with 5 log cycles reduction at 200 μg/mL concentration. PMID:29495318

Trojan-Like Internalization of Anatase Titanium Dioxide Nanoparticles by Human Osteoblast Cells

NASA Astrophysics Data System (ADS)

Ribeiro, A. R.; Gemini-Piperni, S.; Travassos, R.; Lemgruber, L.; C. Silva, R.; Rossi, A. L.; Farina, M.; Anselme, K.; Shokuhfar, T.; Shahbazian-Yassar, R.; Borojevic, R.; Rocha, L. A.; Werckmann, J.; Granjeiro, J. M.

2016-03-01

Dentistry and orthopedics are undergoing a revolution in order to provide more reliable, comfortable and long-lasting implants to patients. Titanium (Ti) and titanium alloys have been used in dental implants and total hip arthroplasty due to their excellent biocompatibility. However, Ti-based implants in human body suffer surface degradation (corrosion and wear) resulting in the release of metallic ions and solid wear debris (mainly titanium dioxide) leading to peri-implant inflammatory reactions. Unfortunately, our current understanding of the biological interactions with titanium dioxide nanoparticles is still very limited. Taking this into consideration, this study focuses on the internalization of titanium dioxide nanoparticles on primary bone cells, exploring the events occurring at the nano-bio interface. For the first time, we report the selective binding of calcium (Ca), phosphorous (P) and proteins from cell culture medium to anatase nanoparticles that are extremely important for nanoparticle internalization and bone cells survival. In the intricate biological environment, anatase nanoparticles form bio-complexes (mixture of proteins and ions) which act as a kind of ‘Trojan-horse’ internalization by cells. Furthermore, anatase nanoparticles-induced modifications on cell behavior (viability and internalization) could be understand in detail. The results presented in this report can inspire new strategies for the use of titanium dioxide nanoparticles in several regeneration therapies.

Trojan-Like Internalization of Anatase Titanium Dioxide Nanoparticles by Human Osteoblast Cells.

PubMed

Ribeiro, A R; Gemini-Piperni, S; Travassos, R; Lemgruber, L; Silva, R C; Rossi, A L; Farina, M; Anselme, K; Shokuhfar, T; Shahbazian-Yassar, R; Borojevic, R; Rocha, L A; Werckmann, J; Granjeiro, J M

2016-03-29

Dentistry and orthopedics are undergoing a revolution in order to provide more reliable, comfortable and long-lasting implants to patients. Titanium (Ti) and titanium alloys have been used in dental implants and total hip arthroplasty due to their excellent biocompatibility. However, Ti-based implants in human body suffer surface degradation (corrosion and wear) resulting in the release of metallic ions and solid wear debris (mainly titanium dioxide) leading to peri-implant inflammatory reactions. Unfortunately, our current understanding of the biological interactions with titanium dioxide nanoparticles is still very limited. Taking this into consideration, this study focuses on the internalization of titanium dioxide nanoparticles on primary bone cells, exploring the events occurring at the nano-bio interface. For the first time, we report the selective binding of calcium (Ca), phosphorous (P) and proteins from cell culture medium to anatase nanoparticles that are extremely important for nanoparticle internalization and bone cells survival. In the intricate biological environment, anatase nanoparticles form bio-complexes (mixture of proteins and ions) which act as a kind of 'Trojan-horse' internalization by cells. Furthermore, anatase nanoparticles-induced modifications on cell behavior (viability and internalization) could be understand in detail. The results presented in this report can inspire new strategies for the use of titanium dioxide nanoparticles in several regeneration therapies.

Selective catalytic reduction system and process for treating NOx emissions using a zinc or titanium promoted palladium-zirconium catalyst

DOEpatents

Sobolevskiy, Anatoly [Orlando, FL; Rossin, Joseph A [Columbus, OH; Knapke, Michael J [Columbus, OH

2011-08-02

A process and system (18) for reducing NO.sub.x in a gas using hydrogen as a reducing agent is provided. The process comprises contacting the gas stream (29) with a catalyst system (38) comprising sulfated zirconia washcoat particles (41), palladium, a pre-sulfated zirconia binder (44), and a promoter (45) comprising at least one of titanium, zinc, or a mixture thereof. The presence of zinc or titanium increases the resistance of the catalyst system to a sulfur and water-containing gas stream.

Peroxy-Titanium Complex-based inks for low temperature compliant anatase thin films.

PubMed

Shabanov, N S; Asvarov, A Sh; Chiolerio, A; Rabadanov, K Sh; Isaev, A B; Orudzhev, F F; Makhmudov, S Sh

2017-07-15

Stable highly crystalline titanium dioxide colloids are of paramount importance for the establishment of a solution-processable library of materials that could help in bringing the advantages of digital printing to the world of photocatalysis and solar energy conversion. Nano-sized titanium dioxide in the anatase phase was synthesized by means of hydrothermal methods and treated with hydrogen peroxide to form Peroxy-Titanium Complexes (PTCs). The influence of hydrogen peroxide on the structural, optical and rheological properties of titanium dioxide and its colloidal solutions were assessed and a practical demonstration of a low temperature compliant digitally printed anatase thin film given. Copyright © 2017 Elsevier Inc. All rights reserved.

Surface Characterization of an Organized Titanium Dioxide Layer

NASA Astrophysics Data System (ADS)

Curtis, Travis

Soft lithographic printing techniques can be used to control the surface morphology of titanium dioxide layers on length scales of several hundred nanometers. Controlling surface morphology and volumetric organization of titanium dioxide electrodes can potentially be used in dye-sensitized solar cell devices. This thesis explores how layer-by-layer replication can lead to well defined, dimensionally controlled volumes and details how these control mechanisms influence surface characteristics of the semiconducting oxide.

Selective defunctionalization by TiO2 of monomeric phenolics from lignin pyrolysis into simple phenols.

PubMed

Mante, Ofei D; Rodriguez, Jose A; Babu, Suresh P

2013-11-01

This study is focused on defunctionalizing monomeric phenolics from lignin into simple phenols for applications such as phenol/formaldehyde resins, epoxidized novolacs, adhesives and binders. Towards this goal, Titanium dioxide (TiO2) was used to selectively remove hydroxyl, methoxy, carbonyl and carboxyl functionalities from the monomeric phenolic compounds from lignin to produce mainly phenol, cresols and xylenols. The results showed that anatase TiO2 was more selective and active compared to rutile TiO2. Catechols were found to be the most reactive phenolics and 4-ethylguaiacol the least reactive with anatase TiO2. An overall conversion of about 87% of the phenolics was achieved at 550°C with a catalyst-to-feed ratio of 5 w/w. Over 97% conversion of phenolics is achievable at moderate temperatures (550°C or ≤ 600°C) and a moderate catalyst-to-feed ratio of 6.5:1. The reactivity of catechols on TiO2 suggests that titania is a promising catalyst in the removal of hydroxyl moiety. Published by Elsevier Ltd.

Ammonia sensing using lossy mode resonances in a tapered optical fibre coated with porphyrin-incorporated titanium dioxide

NASA Astrophysics Data System (ADS)

Tiwari, Divya; Mullaney, Kevin; Korposh, Serhiy; James, Stephen W.; Lee, Seung-Woo; Tatam, Ralph P.

2016-05-01

The development of an ammonia sensor, formed by the deposition of a functionalised titanium dioxide film onto a tapered optical fibre is presented. The titanium dioxide coating allows the coupling of light from the fundamental core mode to a lossy mode supported by the coating, thus creating lossy mode resonance (LMR) in the transmission spectrum. The porphyrin compound that was used to functionalise the coating was removed from the titanium dioxide coating upon exposure to ammonia, causing a change in the refractive index of the coating and a concomitant shift in the central wavelength of the lossy mode resonance. Concentrations of ammonia as small as 1ppm was detected with a response time of less than 1min.

Biological Activity of Mesoporous Dendrimer-Coated Titanium Dioxide: Insight on the Role of the Surface-Interface Composition and the Framework Crystallinity.

PubMed

Milowska, Katarzyna; Rybczyńska, Aneta; Mosiolek, Joanna; Durdyn, Joanna; Szewczyk, Eligia M; Katir, Nadia; Brahmi, Younes; Majoral, Jean-Pierre; Bousmina, Mosto; Bryszewska, Maria; El Kadib, Abdelkrim

2015-09-16

Hitherto, the field of nanomedicine has been overwhelmingly dominated by the use of mesoporous organosilicas compared to their metal oxide congeners. Despite their remarkable reactivity, titanium oxide-based materials have been seldom evaluated and little knowledge has been gained with respect to their "structure-biological activity" relationship. Herein, a fruitful association of phosphorus dendrimers (both "ammonium-terminated" and "phosphonate-terminated") and titanium dioxide has been performed by means of the sol-gel process, resulting in mesoporous dendrimer-coated nanosized crystalline titanium dioxide. A similar organo-coating has been reproduced using single branch-mimicking dendrimers that allow isolation of an amorphous titanium dioxide. The impact of these materials on red blood cells was evaluated by studying cell hemolysis. Next, their cytotoxicity toward B14 Chinese fibroblasts and their antimicrobial activity were also investigated. Based on their variants (cationic versus anionic terminal groups and amorphous versus crystalline titanium dioxide phase), better understanding of the role of the surface-interface composition and the nature of the framework has been gained. No noticeable discrimination was observed for amorphous and crystalline material. In contrast, hemolysis and cytotoxicity were found to be sensitive to the nature of the interface composition, with the ammonium-terminated dendrimer-coated titanium dioxide being the most hemolytic and cytotoxic material. This surface-functionalization opens the door for creating a new synergistic machineries mechanism at the cellular level and seems promising for tailoring the biological activity of nanosized organic-inorganic hybrid materials.

Photocatalytic treatment of RDX wastewater with nano-sized titanium dioxide.

PubMed

Liu, Zongkuan; He, Yanling; Li, Feng; Liu, Yonghong

2006-09-01

The polynitramines, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), are important military explosives and regulated toxic hazardous compounds. Production, testing and use of the compounds has resulted in numerous acres of contaminated soils and groundwater near many munitions facilities. Economical and efficient methods for treatment of wastewater and cleanup of soils or groundwater containing RDX and HMX are needed. This study focuses on the photocatalytic treatment of RDX wastewater with nano-sized titanium dioxide (nano-TiO2) under simulated sunlight, whose intensity and wavelength are similar to that of the real sunlight in Xi'an at noon. The objective is to determine the potential for RDX destruction with nano-TiO2 in aqueous solution. An activated carbon fiber (ACF) cloth-loaded with nano-TiO2 was put into the RDX containing solution, and the concentration of RDX was measured (by HPLC-UV) at regular time intervals under simulated sunlight. The RDX degradation percentage of the photocatalytic process is higher than that of Fenton oxidation before 80 min, equivalent after 80 min, and it reaches 95% or above after 120 min. The nano-TiO2 catalyst can be used repeatedly. The photocatalytic degradation kinetics of RDX under simulated sunlight can be described by a first-order reaction kinetics equation. The possible degradation mechanism of RDX was presented and the degradation performance was compared with that of biological method. It was demonstrated that the degradation of RDX wastewater is very effective with nano-TiO2 as the photocatalytic catalyst under simulated sunlight. The efficiency of the nano-TiO2 catalyst for RDX degradation under simulated sunlight is nearly identical to that of Fenton oxidation. To date, a number of catalysts show poor absorption and utilization of sunlight, and still need ultraviolet light irradiation during wastewater degradation. The nano-TiO2 used in the described experiments features very good degradation of RDX under simulated sunlight, and the manufacturing costs are rather low (around 10 Euro/m2). Moreover, the degradation efficiency is higher compared to that of the biological method. This method exhibits great potential for practical applications owing to its easiness and low cost. If it can be applied extensively, the efficiency of wastewater treatment will be enhanced greatly.

Synergistic effect of the presence of suspended and dissolved matter on the removal of cyanide from coking wastewater by TiO2 photocatalysis.

PubMed

Pueyo, Noelia; Miguel, Natividad; Mosteo, Rosa; Ovelleiro, José L; Ormad, María P

2017-01-28

This study assesses the influence of the presence of suspended and dissolved matter on the efficiency of TiO 2 photocatalysis for the removal of cyanide from coking wastewater. Photocatalytic processes were carried out at basic pH (pH 9) with titanium dioxide (1 g/L), artificial radiation (290-800 nm) and during different time periods (20-100 min). The first assays applied in aqueous solutions achieved promising results in terms of removing cyanide. The maximum cyanide removal obtained in coking wastewater was 89% after 80 min of irradiation in the presence of suspended and dissolved matter. The presence of suspended matter composed of coal improves the efficiency of the photocatalytic process due to the synergistic effect between carbon and TiO 2 . The absence of dissolved matter also improves the process due to the minimization of the hydroxyl radical scavenging effect produced by carbonate and bicarbonate ions. On the other hand, the presence of certain species in the real matrix such as silicon increases the activity of the titanium dioxide catalyst. In consequence, the improvement achieved by the photocatalytic process for the removal of cyanide in the absence of dissolved matter is counteracted.

Tethered catalysts for the hydration of carbon dioxide

DOEpatents

Valdez, Carlos A; Satcher, Jr., Joe H; Aines, Roger D; Wong, Sergio E; Baker, Sarah E; Lightstone, Felice C; Stolaroff, Joshuah K

2014-11-04

A system is provided that substantially increases the efficiency of CO.sub.2 capture and removal by positioning a catalyst within an optimal distance from the air-liquid interface. The catalyst is positioned within the layer determined to be the highest concentration of carbon dioxide. A hydrophobic tether is attached to the catalyst and the hydrophobic tether modulates the position of the catalyst within the liquid layer containing the highest concentration of carbon dioxide.

Photorefractive Effect in Barium Titanate Crystals

DTIC Science & Technology

1988-08-15

photorefractivity. The titanium dioxide feed material was prepared by the hydrolysis of titanium isopropoxide , Ti(ioc3H7 )4 , according to the reaction...reduced pressure fractional distillation. This purification technique was based on the observation that titanium isopropoxide has a much lower boiling...Starting materials A major effort in this research was devoted to the synthesis of high-purity starting materials, since titanium dioxide and barium

21 CFR 73.1350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) Identity. (1) The color additive is formed by depositing titanium and/or iron salts onto mica, followed by heating to produce one of the following combinations: Titanium dioxide on mica; iron oxide on mica; titanium dioxide and iron oxide on mica. Mica used to manufacture the color additive shall conform in...

Peroxide-modified titanium dioxide: a chemical analog of putative Martian soil oxidants

NASA Technical Reports Server (NTRS)

Quinn, R. C.; Zent, A. P.

1999-01-01

Hydrogen peroxide chemisorbed on titanium dioxide (peroxide-modified titanium dioxide) is investigated as a chemical analog to the putative soil oxidants responsible for the chemical reactivity seen in the Viking biology experiments. When peroxide-modified titanium dioxide (anatase) was exposed to a solution similar to the Viking labeled release (LR) experiment organic medium, CO2 gas was released into the sample cell headspace. Storage of these samples at 10 degrees C for 48 hr prior to exposure to organics resulted in a positive response while storage for 7 days did not. In the Viking LR experiment, storage of the Martian surface samples for 2 sols (approximately 49 hr) resulted in a positive response while storage for 141 sols essentially eliminated the initial rapid release of CO2. Heating the peroxide-modified titanium dioxide to 50 degrees C prior to exposure to organics resulted in a negative response. This is similar to, but not identical to, the Viking samples where heating to approximately 46 degrees C diminished the response by 54-80% and heating to 51.5 apparently eliminated the response. When exposed to water vapor, the peroxide-modified titanium dioxide samples release O2 in a manner similar to the release seen in the Viking gas exchange experiment (GEx). Reactivity is retained upon heating at 50 degrees C for three hours, distinguishing this active agent from the one responsible for the release of CO2 from aqueous organics. The release of CO2 by the peroxide-modified titanium dioxide is attributed to the decomposition of organics by outer-sphere peroxide complexes associated with surface hydroxyl groups, while the release of O2 upon humidification is attributed to more stable inner-sphere peroxide complexes associated with Ti4+ cations. Heating the peroxide-modified titanium dioxide to 145 degrees C inhibited the release of O2, while in the Viking experiments heating to this temperature diminished but did not eliminated the response. Although the thermal stability of the titanium-peroxide complexes in this work is lower than the stability seen in the Viking experiments, it is expected that similar types of complexes will form in titanium containing minerals other than anatase and the stability of these complexes will vary with surface hydroxylation and mineralogy.

Thermal, structural and electrochemical properties of new aliphatic-aromatic imine with piperazine moieties blended with titanium dioxide

NASA Astrophysics Data System (ADS)

Różycka, Anna; Fryń, Patryk; Iwan, Agnieszka; Bogdanowicz, Krzysztof Artur; Filapek, Michal; Górska, Natalia; Dąbczyński, Paweł; Rysz, Jakub; Pociecha, Damian; Hreniak, Agnieszka; Marzec, Monika

2018-02-01

A new piperazine imine, (7E)-N-((4-((E)-(4-hexadecylphenylimino)methyl)piperazin-1-yl)methylene)-4-dodecylbenzenamine, has been synthesized by the condensation of 1,4-piperazinedicarboxaldehyde with 4-hexadecylaniline. The imine was characterized by cyclic voltammetry, Fourier transform middle-infrared absorption spectroscopy and X-ray diffraction. Thermal properties of imine was analyzed by differential scanning calorimetry method during first and second heating scan at 10 and 20 °C/min. Texture of imine was investigated by polarized optical microscopy and atomic force microscopy. Furthermore, imine was blended with titanium dioxide in anatase form and fully characterized by the same methods. Piperazine imine and its mixture with titanium dioxide exhibited only a transition from crystal to isotropic state. Imine exhibits two-step reduction wave attributed to one-electron transfer in each step as was found by cyclic voltammetry. Both titanium dioxide and poly(3-hexylthiophene) change the electrochemical properties of piperazine imine, however, in different ways. Studied imine blended with titanium dioxide exhibited higher value of energy band gap than pure piperazine imine and lower Eg than pure poly(3-hexylthiophene).

Characteristics of dye Rhoeo spathacea in dye sensitizer solar cell (DSSC)

NASA Astrophysics Data System (ADS)

Sumardiasih, Sri; Obina, Wilfrida M.; Cari; Supriyanto, Agus; Septiawan, Trio Y.; Khairuddin

2017-01-01

Dye-sensitized solar cell (DSSC) is a device that converts solar energy into electrical energy. The magnitude of the efficiency of DSSC is mainly based on the amount of dye absorbed by the surface of TiO2. In this work, used natural dye extracted from leaves Rhoeo spathacea. The dye partially used to immerse of TiO2 as working electrodes, and the rest are directly mixed TiO2 paste to obtain dye titanium dioxide.The paste TiO2 and dye titanium dioxide coated onto the fluorine-doped tin oxide (FTO) glass plate by spin coating method. The absorbance spectra of the dye, dye titanium dioxide and TiO2 were obtained by UV-Vis spectroscopy. The conductivity of the dye, dye titanium dioxide, and TiO2 was measured by two point probe El-Kahfi 100. The DSSC based on dye titanium dioxide that stirring for 5 hours the highest efficiency of 0,0520 % whereas those based on TiO2 immersed for 36 hours showed achieved 0,0501 % obtained from I-V characterization.

The Effect of Titanium Tetrahedral Coordination of Silica-Titania Catalyst on the Physical Properties of Biodiesel

NASA Astrophysics Data System (ADS)

Nizar, U. K.; Hidayatul, J.; Sundari, R.; Bahrizal, B.; Amran, A.; Putra, A.; Latisma DJ, L.; Dewata, I.

2018-04-01

This study investigates the correlation of the number of titanium tetrahedral coordination and biodiesel production. The solid-state method has been used to synthesis of silica-titania catalyst for biodiesel production, which the precursors, i.e. silica and titania commercials were heated in the temperature range of 450 - 550°C. The characterization of the prepared silica-titania has been studied by FTIR and DR UV-Vis in order to identify and calculate the presence of titanium tetrahedral coordination in silica-titania catalyst. A very small peak at around 950 cm-1 indicated the presence of titanium tetrahedral coordination through Si–O–Ti bonds. Deconvolution of DR UV-Vis spectra showed the coordination of titanium in silica-titania is more octahedral. However, the number of titanium tetrahedral coordination of the prepared silica-titania is found higher than that of TiO2 commercial. The increasing of titanium tetrahedral fraction in silica-titania affects the physical properties of biodiesel in terms of boiling point, viscosity and density, which is produced by the reaction of methanol and palm oil.

21 CFR 73.1575 - Titanium dioxide.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Titanium dioxide. 73.1575 Section 73.1575 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... additive mixtures for coloring drugs, and the following: Silicon dioxide, SiO2, and/or aluminum oxide...

The History of Current State of the Art of Propylene Polymerization Catalysts.

ERIC Educational Resources Information Center

Goodall, Brian L.

1986-01-01

Outlines the development of the modern catalysts for propylene polymerization, considering the historical background; structure of titanium chloride catalysts; first-generation catalysts; cocatalysts; second-generation catalysts; catalysts morphology; and third-generation (supported catalysts). (JN)

21 CFR 73.2575 - Titanium dioxide.

Code of Federal Regulations, 2013 CFR

2013-04-01

... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications... safely used in cosmetics, including cosmetics intended for use in the area of the eye, in amounts...

21 CFR 73.2575 - Titanium dioxide.

Code of Federal Regulations, 2012 CFR

2012-04-01

... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications... safely used in cosmetics, including cosmetics intended for use in the area of the eye, in amounts...

21 CFR 73.2575 - Titanium dioxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications... safely used in cosmetics, including cosmetics intended for use in the area of the eye, in amounts...

Examining the efficiency of muffle furnance-induced alkaline hydrolysis in determining the titanium content of environmental samples containing engineered titanium dioxide particles

EPA Science Inventory

A novel muffle furnace (MF)-based potassium hydroxide (KOH) fusion digestion technique was developed and its comparative digestion and dissolution efficacy for different titanium dioxide nanoparticles (TiO2-NPs)/environmental matrices was evaluated. Digestion of different enviro...

SCAVENGER AND PROCESS OF SCAVENGING

DOEpatents

Olson, C.M.

1960-04-26

Carrier precipitation processes are given for the separation and recovery of plutonium from aqueous acidic solutions containing plutonium and fission products. Bismuth phosphate is precipitated in the acidic solution while plutonlum is maintained in the hexavalent oxidation state. Preformed, uncalcined, granular titanium dioxide is then added to the solution and the fission product-carrying bismuth phosphate and titanium dioxide are separated from the resulting mixture. Fluosilicic acid, which dissolves any remaining titanium dioxide particles, is then added to the purified plutonium-containing solution.

Investigating molecule-semiconductor interfaces with nonlinear spectroscopies

NASA Astrophysics Data System (ADS)

Giokas, Paul George

Knowledge of electronic structures and transport mechanisms at molecule-semiconductor interfaces is motivated by their ubiquity in photoelectrochemical cells. In this dissertation, optical spectroscopies are used uncover the influence of electronic coupling, coherent vibrational motion, and molecular geometry, and other factors on dynamics initiated by light absorption at such interfaces. These are explored for a family of ruthenium bipyridyl chromophores bound to titanium dioxide. Transient absorption measurements show molecular singlet state electron injection in 100 fs or less. Resonance Raman intensity analysis suggests the electronic excitations possess very little charge transfer character. The connections drawn in this work between molecular structure and photophysical behavior contribute to the general understanding of photoelectrochemical cells. Knowledge of binding geometry in nanocrystalline films is challenged by heterogeneity of semiconductor surfaces. Polarized resonance Raman spectroscopy is used to characterize the ruthenium chromophore family on single crystal titanium dioxide . Chromophores display a broad distribution of molecular geometries at the interface, with increased variation in binding angle due to the presence of a methylene bridge, as well as additional phosphonate anchors. This result implies multiple binding configurations for chromophores which incorporate multiple phosphonate ligands, and indicates the need for careful consideration when developing surface-assembled chromophore-catalyst cells. Electron transfer transitions occurring on the 100 fs time scale challenge conventional second-order approximations made when modeling these reactions. A fourth-order perturbative model which includes the relationship between coincident electron transfer and nuclear relaxation processes is presented. Insights provided by the model are illustrated for a two-level donor molecule. The presented fourth-order rate formula constitutes a rigorous and intuitive framework for understanding sub-picosecond photoinduced electron transfer dynamics. Charge transfer systems fit by this model include catechol-sensitized titanium dioxide nanoparticles and a closely-related molecular complex. These systems exhibit vibrational coherence coincident with back-electron transfer in the first picosecond after excitation, which suggests that intramolecular nuclear motion strongly influences the electronic transfer process and plays an important role in the dynamics of interfacial systems following light absorption.

Hybrid Nanomaterials with Single-Site Catalysts by Spatially Controllable Immobilization of Nickel Complexes via Photoclick Chemistry for Alkene Epoxidation.

PubMed

Ghosh, Dwaipayan; Febriansyah, Benny; Gupta, Disha; Ng, Leonard Kia-Sheun; Xi, Shibo; Du, Yonghua; Baikie, Tom; Dong, ZhiLi; Soo, Han Sen

2018-05-22

Catalyst deactivation is a persistent problem not only for the scientific community but also in industry. Isolated single-site heterogeneous catalysts have shown great promise to overcome these problems. Here, a versatile anchoring strategy for molecular complex immobilization on a broad range of semiconducting or insulating metal oxide ( e. g., titanium dioxide, mesoporous silica, cerium oxide, and tungsten oxide) nanoparticles to synthesize isolated single-site catalysts has been studied systematically. An oxidatively stable anchoring group, maleimide, is shown to form covalent linkages with surface hydroxyl functionalities of metal oxide nanoparticles by photoclick chemistry. The nanocomposites have been thoroughly characterized by techniques including UV-visible diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, and X-ray absorption spectroscopy (XAS). The IR spectroscopic studies confirm the covalent linkages between the maleimide group and surface hydroxyl functionalities of the oxide nanoparticles. The hybrid nanomaterials function as highly efficient catalysts for essentially quantitative oxidations of terminal and internal alkenes and show molecular catalyst product selectivities even in more eco-friendly solvents. XAS studies verify the robustness of the catalysts after several catalytic cycles. We have applied the photoclick anchoring methodology to precisely control the deposition of a luminescent variant of our catalyst on the metal oxide nanoparticles. Overall, we demonstrate a general approach to use irradiation to anchor molecular complexes on oxide nanoparticles to create recyclable, hybrid, single-site catalysts that function with high selectivity in a broad range of solvents. We have achieved a facile, spatially and temporally controllable photoclick method that can potentially be extended to other ligands, catalysts, functional molecules, and surfaces.

Composite materials and bodies including silicon carbide and titanium diboride and methods of forming same

DOEpatents

Lillo, Thomas M.; Chu, Henry S.; Harrison, William M.; Bailey, Derek

2013-01-22

Methods of forming composite materials include coating particles of titanium dioxide with a substance including boron (e.g., boron carbide) and a substance including carbon, and reacting the titanium dioxide with the substance including boron and the substance including carbon to form titanium diboride. The methods may be used to form ceramic composite bodies and materials, such as, for example, a ceramic composite body or material including silicon carbide and titanium diboride. Such bodies and materials may be used as armor bodies and armor materials. Such methods may include forming a green body and sintering the green body to a desirable final density. Green bodies formed in accordance with such methods may include particles comprising titanium dioxide and a coating at least partially covering exterior surfaces thereof, the coating comprising a substance including boron (e.g., boron carbide) and a substance including carbon.

Titanium Dioxide Nanoparticles in Food and Personal Care Products

PubMed Central

Weir, Alex; Westerhoff, Paul; Fabricius, Lars

2012-01-01

Titanium dioxide is a common additive in many food, personal care, and other consumer products used by people, which after use can enter the sewage system, and subsequently enter the environment as treated effluent discharged to surface waters or biosolids applied to agricultural land, incinerated wastes, or landfill solids. This study quantifies the amount of titanium in common food products, derives estimates of human exposure to dietary (nano-) TiO2, and discusses the impact of the nanoscale fraction of TiO2 entering the environment. The foods with the highest content of TiO2 included candies, sweets and chewing gums. Among personal care products, toothpastes and select sunscreens contained 1% to >10% titanium by weight. While some other crèmes contained titanium, despite being colored white, most shampoos, deodorants, and shaving creams contained the lowest levels of titanium (<0.01 μg/mg). For several high-consumption pharmaceuticals, the titanium content ranged from below the instrument detection limit (0.0001 μg Ti/mg) to a high of 0.014 μg Ti/mg. Electron microscopy and stability testing of food-grade TiO2 (E171) suggests that approximately 36% of the particles are less than 100 nm in at least one dimension and that it readily disperses in water as fairly stable colloids. However, filtration of water solubilized consumer products and personal care products indicated that less than 5% of the titanium was able to pass through 0.45 or 0.7 μm pores. Two white paints contained 110 μg Ti/mg while three sealants (i.e., prime coat paint) contained less titanium (25 to 40 μg Ti/mg). This research showed that while many white-colored products contained titanium, it was not a prerequisite. Although several of these product classes contained low amounts of titanium, their widespread use and disposal down the drain and eventually to WWTPs deserves attention. A Monte Carlo human exposure analysis to TiO2 through foods identified children as having the highest exposures because TiO2 content of sweets is higher than other food products, and that a typical exposure for a US adult may be on the order of 1 mg Ti per kilogram body weight per day. Thus, because of the millions of tons of titanium based white pigment used annually, testing should focus on food-grade TiO2 (E171) rather than that adopted in many environmental health and safety tests (i.e., P25), which is used in much lower amounts in products less likely to enter the environment (e.g., catalyst supports, photocatalytic coatings). PMID:22260395

On the water promoted reaction of titanium isopropoxide with carbon dioxide.

PubMed

Ghosh, Rajshekhar; Nethaji, Munirathinam; Samuelson, Ashoka G

2003-10-21

Insertion of carbon dioxide into titanium isopropoxide takes place only in the presence of trace quantities of water to give an isopropyl carbonato cluster which has been crystallographically characterised.

Exposure to nano-size titanium dioxide causes oxidative damages in human mesothelial cells: The crystal form rather than size of particle contributes to cytotoxicity.

PubMed

Hattori, Kenji; Nakadate, Kazuhiko; Morii, Akane; Noguchi, Takumi; Ogasawara, Yuki; Ishii, Kazuyuki

2017-10-14

Exposure to nanoparticles such as carbon nanotubes has been shown to cause pleural mesothelioma similar to that caused by asbestos, and has become an environmental health issue. Not only is the percutaneous absorption of nano-size titanium dioxide particles frequently considered problematic, but the possibility of absorption into the body through the pulmonary route is also a concern. Nevertheless, there are few reports of nano-size titanium dioxide particles on respiratory organ exposure and dynamics or on the mechanism of toxicity. In this study, we focused on the morphology as well as the size of titanium dioxide particles. In comparing the effects between nano-size anatase and rutile titanium dioxide on human-derived pleural mesothelial cells, the anatase form was shown to be actively absorbed into cells, producing reactive oxygen species and causing oxidative damage to DNA. In contrast, we showed for the first time that the rutile form is not easily absorbed by cells and, therefore, does not cause oxidative DNA damage and is significantly less damaging to cells. These results suggest that with respect to the toxicity of titanium dioxide particles on human-derived mesothelial cells, the crystal form rather than the particle size has a greater effect on cellular absorption. Also, it was indicated that the difference in absorption is the primary cause of the difference in the toxicity against mesothelial cells. Copyright © 2017 Elsevier Inc. All rights reserved.

19 CFR 191.26 - Recordkeeping for manufacturing drawback.

Code of Federal Regulations, 2014 CFR

2014-04-01

... analysis in the entry papers to be 91.7% pure titanium dioxide is imported and dutiable at a 5% ad valorem.... The total duty paid is $600. Titanium in the synthetic rutile is designated as the basis for a drawback claim under 19 U.S.C. 1313(b). The amount of titanium dioxide in the synthetic rutile is...

Radiation absorption and optimization of solar photocatalytic reactors for environmental applications.

PubMed

Colina-Márquez, Jose; Machuca-Martínez, Fiderman; Li Puma, Gianluca

2010-07-01

This study provides a systematic and quantitative approach to the analysis and optimization of solar photocatalytic reactors utilized in environmental applications such as pollutant remediation and conversion of biomass (waste) to hydrogen. Ray tracing technique was coupled with the six-flux absorption scattering model (SFM) to analyze the complex radiation field in solar compound parabolic collectors (CPC) and tubular photoreactors. The absorption of solar radiation represented by the spatial distribution of the local volumetric rate of photon absorption (LVRPA) depends strongly on catalyst loading and geometry. The total radiation absorbed in the reactors, the volumetric rate of absorption (VRPA), was analyzed as a function of the optical properties (scattering albedo) of the photocatalyst. The VRPA reached maxima at specific catalyst concentrations in close agreement with literature experimental studies. The CPC has on average 70% higher photon absorption efficiency than a tubular reactor and requires 39% less catalyst to operate under optimum conditions. The "apparent optical thickness" is proposed as a new dimensionless parameter for optimization of CPC and tubular reactors. It removes the dependence of the optimum catalyst concentration on tube diameter and photocatalyst scattering albedo. For titanium dioxide (TiO(2)) Degussa P25, maximum photon absorption occurs at apparent optical thicknesses of 7.78 for CPC and 12.97 for tubular reactors.

Synergy between hexavalent chromium ions and TiO2 nanoparticles inside TUD-1 in the photocatalytic oxidation of propane, a spectroscopic study

NASA Astrophysics Data System (ADS)

Hamdy, Mohamed S.

2016-02-01

Siliceous TUD-1 mesoporous material was bi-functionalized by titanium dioxide nanoparticles and hexavalent chromium ions. The synthesis was carried out by one-pot procedure based on sol-gel technique. The photocatalytic performance of the prepared material was evaluated in the oxidation of propane under the illumination of ultraviolet light (wavelength = 360 nm) and monitored by in situ Fourier transform infrared spectroscopy. The photocatalytic activity of the prepared material exhibited an extra-ordinary activity than the reference samples that contain either hexavalent chromium ions or titanium dioxide nanoparticles only, confirming the true synergy between hexavalent chromium and tetravalent titanium ions of titanium dioxide nanoparticles.

Titanium-based zeolitic imidazolate framework for chemical fixation of carbon dioxide

EPA Science Inventory

A titanium-based zeolitic imidazolate framework (Ti-ZIF) with high surface area and porous morphology was synthesized and itsefficacy was demonstrated in the synthesis of cyclic carbonates from epoxides and carbon dioxide.

Cyclic thermochemical process for producing hydrogen using cerium-titanium compounds

DOEpatents

Bamberger, Carlos E.

1980-01-01

A thermochemical cyclic process for producing hydrogen employs the reaction between ceric oxide and titanium dioxide to form cerium titanate and oxygen. The titanate is treated with an alkali metal hydroxide to give hydrogen, ceric oxide, an alkali metal titanate and water. Alkali metal titanate and water are boiled to give titanium dioxide which, along with ceric oxide, is recycled.

Cyclic thermochemical process for producing hydrogen using cerium-titanium compounds

DOEpatents

Bamberger, C.E.

A thermochemical cyclic process for producing hydrogen employs the reaction between ceric oxide and titanium dioxide to form cerium titanate and oxygen. The titanate is treated with an alkali metal hydroxide to give hydrogen, ceric oxide, an alkali metal titanate and water. Alkali metal titanate and water are boiled to give titanium dioxide which, along with ceric oxide, is recycled.

Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

NASA Astrophysics Data System (ADS)

Singh, S. C.; Kotnala, R. K.; Gopal, R.

2015-08-01

Intrinsic Room Temperature Ferromagnetism (RTF) has been observed in undoped/uncapped zinc oxide and titanium dioxide spherical nanoparticles (NPs) obtained by a purely green approach of liquid phase pulsed laser ablation of corresponding metal targets in pure water. Saturation magnetization values observed for zinc oxide (average size, 9 ± 1.2 nm) and titanium dioxide (average size, 4.4 ± 0.3 nm) NPs are 62.37 and 42.17 memu/g, respectively, which are several orders of magnitude larger than those of previous reports. In contrast to the previous works, no postprocessing treatments or surface modification is required to induce ferromagnetism in the case of present communication. The most important result, related to the field of intrinsic ferromagnetism in nonmagnetic materials, is the observation of size dependent ferromagnetism. Degree of ferromagnetism in titanium dioxide increases with the increase in particle size, while it is reverse for zinc oxide. Surface and volume defects play significant roles for the origin of RTF in zinc oxide and titanium dioxide NPs, respectively. Single ionized oxygen and neutral zinc vacancies in zinc oxide and oxygen and neutral/ionized titanium vacancies in titanium dioxide are considered as predominant defect centres responsible for observed ferromagnetism. It is expected that origin of ferromagnetism is a consequence of exchange interactions between localized electron spin moments resulting from point defects.

Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, S. C., E-mail: subhash.laserlab@gmail.com; Gopal, R.; Kotnala, R. K.

2015-08-14

Intrinsic Room Temperature Ferromagnetism (RTF) has been observed in undoped/uncapped zinc oxide and titanium dioxide spherical nanoparticles (NPs) obtained by a purely green approach of liquid phase pulsed laser ablation of corresponding metal targets in pure water. Saturation magnetization values observed for zinc oxide (average size, 9 ± 1.2 nm) and titanium dioxide (average size, 4.4 ± 0.3 nm) NPs are 62.37 and 42.17 memu/g, respectively, which are several orders of magnitude larger than those of previous reports. In contrast to the previous works, no postprocessing treatments or surface modification is required to induce ferromagnetism in the case of present communication. The most important result, relatedmore » to the field of intrinsic ferromagnetism in nonmagnetic materials, is the observation of size dependent ferromagnetism. Degree of ferromagnetism in titanium dioxide increases with the increase in particle size, while it is reverse for zinc oxide. Surface and volume defects play significant roles for the origin of RTF in zinc oxide and titanium dioxide NPs, respectively. Single ionized oxygen and neutral zinc vacancies in zinc oxide and oxygen and neutral/ionized titanium vacancies in titanium dioxide are considered as predominant defect centres responsible for observed ferromagnetism. It is expected that origin of ferromagnetism is a consequence of exchange interactions between localized electron spin moments resulting from point defects.« less

Durable warmth retention finishing of down using titanium dioxide optimized by RSM

NASA Astrophysics Data System (ADS)

Li, Huihao; Qi, Lu; Li, Jun

2017-03-01

A new product, referred to herein as modified down, was prepared by grafting down fiber with titanium dioxide. Grafting modification brings new functionalities to down Using response surface methodology (RSM); the effect of titanium dioxide concentration, KH550 concentration, and baking temperature on the warmth retention is studied using the response surface method (RSM) to obtain the optimal experimental formula and models. The optimal preparation conditions for modified down were 19.35% titanium dioxide, 15.81% KH550, 10min baking time, and 115 °C temperature. The warmth retention of the modified down was 79.98%, The structure and property of modified down were characterized and analyzed by using Flat Plate Warmth Retaining Tester, FT-IR, and TG. The CLO value increased by 27.28%, the thermal resistance increased by 27.34%. The ultimate residual quantities of the modified down fibers were 30.05%.

Simultaneous photodegradation of VOC mixture by TiO2 powders.

PubMed

Stucchi, Marta; Galli, Federico; Bianchi, Claudia L; Pirola, Carlo; Boffito, Daria C; Biasioli, Franco; Capucci, Valentino

2018-02-01

Volatile and semi volatile organic compounds' concentration have dramatically increased in indoor environments in recent years. UV light promotes titanium dioxide, which oxidises various molecules; however, most of the studies report the degradation of a single VOC. Here, we investigate the photo-oxidation of 17 molecules in mixture to have a realistic test of TiO 2 efficacy. We compare P25, a nanometric catalyst, and 1077, a micrometric sample, that poses less health concerns. A proton-transfer-reaction mass spectrometer measured online the concentration of all the pollutants simultaneously. Aldehydes compete for the adsorption on both the catalyst's active sites and thus they degrade 70% and 55% with P25 and 1077 respectively. Considering the single pollutant oxidation, instead, aldehydes fully oxidize. Even though benzene is recalcitrant to degradation, P25 and 1077 reduced toluene's concentration to 97% and 96% in 55 min, respectively. Acetonitrile is refractory to photocatalysis. Copyright © 2017. Published by Elsevier Ltd.

A study on heterogeneous photocatalytic degradation of various organic compounds using N-Tio2 under Uv-light irradiation

NASA Astrophysics Data System (ADS)

Srujana, Dhegam; Sailu, Chinta

2018-04-01

The aim of this work is to determine the photocatalytic degradation of mixture of four selected organic compounds are Congo Red (CR), Methylene Blue (MB), Diclofenaec (DC), 4-Chlorophenol (4-CP) have been subjected to Photo catalytic degradation by Ultraviolet (λ=254nm) radiation in presence of Nitrogen-doped Titanium dioxide (N-TiO2) catalyst. This paper focused on the enhancement of photo catalysis by modification of TiO2 employing non-metal ion (Nitrogen) doping. Experiments are conducted with a mixture of equal proportions of organic compounds (CR, MB, DC, and 4-CP) with combined concentrations of 10, 20, 30, 40 and 50 mg/l in water in a batch reactor in presence of N-TiO2catalyst with UV light (λ=254nm). The rate of degradation of each compound is determined by using spectrophotometer. The kinetics of degradation of the selected organic compounds is followed first order rate.

Biomineralized diamond-like carbon films with incorporated titanium dioxide nanoparticles improved bioactivity properties and reduced biofilm formation.

PubMed

Lopes, F S; Oliveira, J R; Milani, J; Oliveira, L D; Machado, J P B; Trava-Airoldi, V J; Lobo, A O; Marciano, F R

2017-12-01

Recently, the development of coatings to protect biomedical alloys from oxidation, passivation and to reduce the ability for a bacterial biofilm to form after implantation has emerged. Diamond-like carbon films are commonly used for implanted medical due to their physical and chemical characteristics, showing good interactions with the biological environment. However, these properties can be significantly improved when titanium dioxide nanoparticles are included, especially to enhance the bactericidal properties of the films. So far, the deposition of hydroxyapatite on the film surface has been studied in order to improve biocompatibility and bioactive behavior. Herein, we developed a new route to obtain a homogeneous and crystalline apatite coating on diamond-like carbon films grown on 304 biomedical stainless steel and evaluated its antibacterial effect. For this purpose, films containing two different concentrations of titanium dioxide (0.1 and 0.3g/L) were obtained by chemical vapor deposition. To obtain the apatite layer, the samples were soaked in simulated body fluid solution for up to 21days. The antibacterial activity of the films was evaluated by bacterial eradication tests using Staphylococcus aureus biofilm. Scanning electron microscopy, X-ray diffraction, Raman scattering spectroscopy, and goniometry showed that homogeneous, crystalline, and hydrophilic apatite films were formed independently of the titanium dioxide concentration. Interestingly, the diamond-like films containing titanium dioxide and hydroxyapatite reduced the biofilm formation compared to controls. A synergism between hydroxyapatite and titanium dioxide that provided an antimicrobial effect against opportunistic pathogens was clearly observed. Copyright © 2017 Elsevier B.V. All rights reserved.

Titanium dioxide-gold nanocomposite materials embedded in silicate sol-gel film catalyst for simultaneous photodegradation of hexavalent chromium and methylene blue.

PubMed

Pandikumar, Alagarsamy; Ramaraj, Ramasamy

2012-02-15

Aminosilicate sol-gel supported titanium dioxide-gold (EDAS/(TiO(2)-Au)(nps)) nanocomposite materials were synthesized by simple deposition-precipitation method and characterized. The photocatalytic oxidation and reduction activity of the EDAS/(TiO(2)-Au)(nps) film was evaluated using hexavalent chromium (Cr(VI)) and methylene blue (MB) dye under irradiation. The photocatalytic reduction of Cr(VI) to Cr(III) was studied in the presence of hole scavengers such as oxalic acid (OA) and methylene blue (MB). The photocatalytic degradation of MB was investigated in the presence and absence of Cr(VI). Presence of Au(nps) on the (TiO(2))(nps) surface and its dispersion in the silicate sol-gel film (EDAS/(TiO(2)-Au)(nps)) improved the photocatalytic reduction of Cr(VI) and oxidation of MB due to the effective interfacial electron transfer from the conduction band of the TiO(2) to Au(nps) by minimizing the charge recombination process when compared to the TiO(2) and (TiO(2)-Au)(nps) in the absence of EDAS. The EDAS/(TiO(2)-Au)(nps) nanocomposite materials provided beneficial role in the environmental remediation and purification process through synergistic photocatalytic activity by an advanced oxidation-reduction processes. Copyright © 2011 Elsevier B.V. All rights reserved.

Three-dimensional ordered titanium dioxide-zirconium dioxide film-based microfluidic device for efficient on-chip phosphopeptide enrichment.

PubMed

Zhao, De; He, Zhongyuan; Wang, Gang; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang

2016-09-15

Microfluidic technology plays a significant role in separating biomolecules, because of its miniaturization, integration, and automation. Introducing micro/nanostructured functional materials can improve the properties of microfluidic devices, and extend their application. Inverse opal has a three-dimensional ordered net-like structure. It possesses a large surface area and exhibits good mass transport, making it a good candidate for bio-separation. This study exploits inverse opal titanium dioxide-zirconium dioxide films for on-chip phosphopeptide enrichment. Titanium dioxide-zirconium dioxide inverse opal film-based microfluidic devices were constructed from templates of 270-, 340-, and 370-nm-diameter poly(methylmethacrylate) spheres. The phosphopeptide enrichments of these devices were determined by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The device constructed from the 270-nm-diameter sphere template exhibited good comprehensive phosphopeptide enrichment, and was the best among these three devices. Because the size of opal template used in construction was the smallest, the inverse opal film therefore had the smallest pore sizes and the largest surface area. Enrichment by this device was also better than those of similar devices based on nanoparticle films and single component films. The titanium dioxide-zirconium dioxide inverse opal film-based device provides a promising approach for the efficient separation of various biomolecules. Copyright © 2016 Elsevier Inc. All rights reserved.

Photocatalytic surface reactions on indoor wall paint.

PubMed

Salthammer, T; Fuhrmann, F

2007-09-15

The reduction of indoor air pollutants by air cleaning systems has received considerable interest, and a number of techniques are now available. So far, the method of photocatalysis was mainly applied by use of titanium dioxide (TiO2) in flow reactors under UV light of high intensity. Nowadays, indoor wall paints are equipped with modified TiO2 to work as a catalyst under indoor daylight or artificial light. In chamber experiments carried out under indoor related conditions itwas shown thatthe method works for nitrogen dioxide with air exchange and for formaldehyde without air exchange at high concentrations. In further experiments with volatile organic compounds (VOCs), a small effect was found for terpenoids with high kOH rate constants. For other VOCs and carbon monoxide there was no degradation at all or the surface acted as a reversible sink. Secondary emissions from the reaction of paint constituents were observed on exposure to light. From the results it is concluded that recipes of photocatalytic wall paints need to be optimized for better efficiency under indoor conditions.

Multispectroscopic (FTIR, XPS, and TOFMS-TPD) Investigation of the Core-Shell Bonding in Sonochemically-Prepared Aluminum Nanoparticles Capped with Oleic Acid (Preprint)

DTIC Science & Technology

2010-04-01

dimethylethylamine and a titanium (IV) isopropoxide catalyst were added to the solution. The concentrations of the alane complex and titanium catalyst in...public release 3.0 METHODS, ASSUMPTIONS, AND PROCEDURES 3.1 Materials Alane N,N-dimethylethylamine in a 0.4 M toluene solution, titanium (IV... isopropoxide (98%), oleic acid (99%), dodecane (99% and anhydrous), and oleyl alcohol (99%) were all obtained from Aldrich and used as received

Multispectroscopic (FTIR, XPS, and TOFMS-TPD) Investigation of the Core-Shell Bonding in Sonochemically Prepared Aluminum Nanoparticles Capped with Oleic Acid (Postprint)

DTIC Science & Technology

2010-03-04

Alane N,N-dimethylethylamine in a 0.4 M toluene solution, titanium (IV) isopropoxide (98%), oleic acid (99%), dodecane (99% and anhydrous), and oleyl...inside a dry nitrogen glovebox, where alane N,N-dimethylethylamine and a titanium (IV) isopropoxide catalyst were added to the solution. The...concentrations of the alane complex and titanium catalyst in this solution were 50 and 0.55 mM, respectively. This solution was then transferred into a sonication

The Morphology of Titanium Dioxide Aerogels

NASA Astrophysics Data System (ADS)

Zhu, Zhu

The morphology of titanium dioxide TiO _2 aerogels has been characterized by four major techniques. This work will discuss these complementary techniques such as nitrogen adsorption, X-ray powder diffraction (XRD), electron microscopies (EM- TEM, SEM), and small angle neutron scattering (SANS). The results of these characterizations have shown that the morphology of titanium dioxide TiO_2 aerogels can be characterized in terms of two length scales: 5 nm diameter, crystalline nanoparticles of anatase closely packed into mesoaggregates about 50 nm in size. The mesoaggregates are, in turn, packed into a loosely linked structure with an overall porosity of 80%.

Biotemplated Synthesis of Anatase Titanium Dioxide Nanoparticles via Lignocellulosic Waste Material

PubMed Central

Bagheri, Samira; Abd Hamid, Sharifah Bee

2014-01-01

Anatase titanium dioxide nanoparticles (TiO2-NPs) were synthesized by sol-gel method using rice straw as a soft biotemplate. Rice straw, as a lignocellulosic waste material, is a biomass feedstock which is globally produced in high rate and could be utilized in an innovative approach to manufacture a value-added product. Rice straw as a reliable biotemplate has been used in the sol-gel method to synthesize ultrasmall sizes of TiO2-NPs with high potential application in photocatalysis. The physicochemical properties of titanium dioxide nanoparticles were investigated by a number of techniques such as X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), ultraviolet visible spectra (UV-Vis), and surface area and pore size analysis. All results consensually confirmed that particle sizes of synthesized titanium dioxide were template-dependent, representing decrease in the nanoparticles sizes with increase of biotemplate concentration. Titanium dioxide nanoparticles as small as 13.0 ± 3.3 nm were obtained under our experimental conditions. Additionally, surface area and porosity of synthesized TiO2-NPs have been enhanced by increasing rice straw amount which results in surface modification of nanoparticles and potential application in photocatalysis. PMID:25126547

Effect of doping on the photocatalytic, electronic and mechanical properties of sol-gel titanium dioxide films

NASA Astrophysics Data System (ADS)

Kurtoglu, Murat

Heterogeneous photocatalysis has been an active research area over the last decade as a promising solution for energy generation and environmental problems which has led to promising applications from air and water purification systems, self-cleaning and self-sterilizing surfaces to solar cells and hydrogen production from water dissociation reaction. Titanium dioxide (TiO2), an abundant material with a high photocatalytic efficiency and chemical stability, is undoubtedly the most widely studied and used among all photocatalytic materials. Although titanium dioxide has been used in powder form, its immobilized form (film) is necessary from practical application standpoint. However, there are several shortcomings of titanium dioxide films that need to be addressed to realize a wide range of successful applications: lack of visible light activity, poisoning of the catalytic performance by the substrate and the low surface area compared to powder forms. In addition, mechanical properties of such films have not been investigated thoroughly, which may be critical when abrasion and weathering resistance are necessary. To address each of these issues, a systematic experimental and theoretical investigation of doping titanium dioxide films with a variety of elements were conducted. Utilizing theoretical calculations to filter elements for experimental studies as well as interpretation of the experimental results, several dopant or dopant combinations were found to remedy some of the issues of photocatalytic titanium dioxide films. Doping with 32 metals, nitrogen and 11 metal-nitrogen combinations are investigated theoretically and the results are used as guideline for the experimental studies. Particular attention is given to certain metal dopants such as Cr, V, Mo, Ta and Ga not just because of their relatively modest cost but also their non-toxicity and wide availability of their compatible compounds for sol-gel synthesis. While metal-dopants improved the overall efficiency and mechanical properties of titanium dioxide films, visible light activity is only achieved with nitrogen and metal-nitrogen doping where some of the metal co-dopants significantly improved the overall photocatalytic efficiency compared to nitrogen-only doped films. In addition, majority of the experimental studies is accompanied by nanoindentation technique to study the effect of doping and calcination on the key mechanical properties of titanium dioxide films. It is shown that good mechanical properties---good photocatalytic activity combinations can be achieved by a choice of appropriate dopant---dopant combinations and coupled with appropriate calcination parameters. Results of the theoretical and experimental investigations led to the development of first commercial photocatalytic tableware glass items which can be utilized under indoor lighting conditions by carefully selecting metal-nitrogen couples for doping of titanium dioxide films.

Allylic aminations with hindered secondary amine nucleophiles catalyzed by heterobimetallic Pd-Ti complexes.

PubMed

Walker, Whitney K; Anderson, Diana L; Stokes, Ryjul W; Smith, Stacey J; Michaelis, David J

2015-02-06

Phosphinoamide-scaffolded heterobimetallic palladium-titanium complexes are highly effective catalysts for allylic aminations of allylic chlorides with hindered secondary amine nucleophiles. Three titanium-containing ligands are shown to assemble active catalysts in situ and enable catalysis at room temperature. A variety of sterically bulky secondary amines are efficiently allylated in high yields with as little as 1 mol % palladium catalyst. Piperidine and pyrrolidine products are also efficiently generated via intramolecular aminations with hindered amine nucleophiles.

Polymorph-dependent titanium dioxide nanoparticle dissolution in acidic and alkali digestions

EPA Science Inventory

Multiple polymorphs (anatase, brookite and rutile) of titanium dioxide nanoparticles (TiO2-NPs) with variable structures were quantified in environmental matrices via microwave-based hydrofluoric (HF) and nitric (HNO3) mixed acid digestion and muffle furnace (MF)-based potassium ...

Titanium dioxide nanoparticles cause genotoxicity in human lung epithelial cells

EPA Science Inventory

The use of engineered nanoparticles in consumer products is steadily increasing. However, the health effects of exposure to these nanoparticles are not thoroughly understood. This study investigated the genotoxicity of six titanium dioxide and two cerium oxide nanoparticles of va...

Tailor-made Molecular Cobalt Catalyst System for the Selective Transformation of Carbon Dioxide to Dialkoxymethane Ethers.

PubMed

Schieweck, Benjamin G; Klankermayer, Jürgen

2017-08-28

Herein a non-precious transition-metal catalyst system for the selective synthesis of dialkoxymethane ethers from carbon dioxide and molecular hydrogen is presented. The development of a tailored catalyst system based on cobalt salts in combination with selected Triphos ligands and acidic co-catalysts enabled a synthetic pathway, avoiding the oxidation of methanol to attain the formaldehyde level of the central CH 2 unit. This unprecedented productivity based on the molecular cobalt catalyst is the first example of a non-precious transition-metal system for this transformation utilizing renewable carbon dioxide sources. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation.

EPA Science Inventory

Titanium dioxide in the anatase crystalline form was used as a photocatalyst to generate hydroxyl radicals in a flowthrough water reactor. Experiments were performed on pure cultures of Escherichia coli in dechlorinated tap water and a surface water sample to evaluate the disinfe...

Fabrication of solar light induced Fe-TiO{sub 2} immobilized on glass-fiber and application for phenol photocatalytic degradation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Shaohua, E-mail: linsh75@163.com; Zhang, Xiwang; Sun, Qinju

2013-11-15

Graphical abstract: - Highlights: • Fe-doped TiO{sub 2} immobilized on glass-fiber net were prepared by sol–gel method. • Fe inhibited the phase transition of TiO{sub 2} from anatase to rutile. • The optimal Fe doping dose was around 0.005 wt%. • The optimal calcination temperature was around 600 °C. - Abstract: Iron-doped anatase titanium dioxide catalysts coated on glass-fiber were successfully synthesized by a dip-coating sol–gel method. The prepared catalysts were characterized by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy to understand the synthesis mechanism, and their photocatalytic activities weremore » evaluated by photodegradation of phenol under simulated solar irradiation. EDX analysis confirmed the existence of iron in the immobilized catalysts. XRD suggested that the phase transition of the catalysts from anatase to rutile were restrained, and almost pure anatase TiO{sub 2} could retain even the calcination temperature reached 800 °C. The UV-Vis diffuse reflectance spectroscopy of the catalysts showed a red shift and increased photoabsorbance in the visible range for all the doped samples. Iron loading and calcination temperature have obvious influences on photocatalytic activity. In this study, the optimal doping dose and calcination temperature were around 0.005 wt% and 600 °C, respectively.« less

Synthesis, characterization and photocatalytic activity of porous manganese oxide doped titania for toluene decomposition.

PubMed

Jothiramalingam, R; Wang, M K

2007-08-17

The present study describes the photocatalytic degradation of toluene in gas phase on different porous manganese oxide doped titanium dioxide. As synthesized birnessite and cryptomelane type porous manganese oxide were doped with titania and tested for photocatalytic decomposition of toluene in gas phase. The effects of the inlet concentration of toluene, flow rate (retention time) were examined and the relative humidity was maintained constantly. Thermal and textural characterization of manganese oxide doped titania materials were characterized by X-ray diffraction (XRD), thermogravemetry (TG), BET and TEM-EDAX studies. The aim of the present study is to synthesize the porous manganese oxide doped titania and to study its photocatalytic activity for toluene degradation in gas phase. Cryptomelane doped titania catalyst prepared in water medium [K-OMS-2 (W)] is shown the good toluene degradation with lower catalysts loading compared to commercial bulk titania in annular type photo reactor. The higher photocatalytic activity due to various factors such as catalyst preparation method, experimental conditions, catalyst loading, surface area, etc. In the present study manganese oxide OMS doped titania materials prepared by both aqueous and non-aqueous medium, aqueous medium prepared catalyst shows the good efficiency due to the presence of OH bonded groups on the surface of catalyst. The linear forms of different kinetic equations were applied to the adsorption data and their goodness of fit was evaluated based on the R2 and standard error. The goodness to the linear fit was observed for Elovich model with high R2 (>or=0.9477) value.

Renewable Acrylonitrile Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beckham, Gregg T; Karp, Eric M; Eaton, Todd R

Acrylonitrile (ACN) is a petroleum-derived compound used in resins, polymers, acrylics, and carbon fiber. We present a process for renewable ACN production using 3-hydroxypropionic acid (3-HP), which can be produced microbially from sugars. The process achieves ACN molar yields exceeding 90% from ethyl 3-hydroxypropanoate (ethyl 3-HP) via dehydration and nitrilation with ammonia over an inexpensive titanium dioxide solid acid catalyst. We further describe an integrated process modeled at scale that is based on this chemistry and achieves near-quantitative ACN yields (98 +/- 2%) from ethyl acrylate. This endothermic approach eliminates runaway reaction hazards and achieves higher yields than the standardmore » propylene ammoxidation process. Avoidance of hydrogen cyanide as a by-product also improves process safety and mitigates product handling requirements.« less

Kinetic modeling of the photocatalytic degradation of clofibric acid in a slurry reactor.

PubMed

Manassero, Agustina; Satuf, María Lucila; Alfano, Orlando Mario

2015-01-01

A kinetic study of the photocatalytic degradation of the pharmaceutical clofibric acid is presented. Experiments were carried out under UV radiation employing titanium dioxide in water suspension. The main reaction intermediates were identified and quantified. Intrinsic expressions to represent the kinetics of clofibric acid and the main intermediates were derived. The modeling of the radiation field in the reactor was carried out by Monte Carlo simulation. Experimental runs were performed by varying the catalyst concentration and the incident radiation. Kinetic parameters were estimated from the experiments by applying a non-linear regression procedure. Good agreement was obtained between model predictions and experimental data, with an error of 5.9 % in the estimations of the primary pollutant concentration.

Identification of Plant Growth-Promoting Bacteria Using Titanium Dioxide Photocatalysis-Assisted Photoacoustic Technique

NASA Astrophysics Data System (ADS)

Gordillo-Delgado, F.; Marín, E.; Calderón, A.

2013-09-01

The effect of titanium dioxide photocatalysis against bacteria that are dangerous for human health has been investigated in the past, suggesting the possibility of using a specific behavior for each microorganism during this process for its discrimination. In this study, the behavior of some plants’ growth promoting bacteria ( Burkholderia unamae (Strain MTI 641), Acetobacter diazotrophicus (Strain PAl 5T), A. diazotrophicus (Strain CFN-Cf 52), and B. unamae (Strain TATl-371)) interacting with light and bactericidal titanium dioxide films have been analyzed using the photoacoustic technique. The monitoring of these interactions shows particular characteristics that could serve for identifying these species.

Thermochemical generation of hydrogen and oxygen from water

DOEpatents

Robinson, Paul R.; Bamberger, Carlos E.

1981-01-01

A thermochemical cyclic process for the production of hydrogen exploits the reaction between sodium manganate (NaMnO.sub.2) and titanium dioxide (TiO.sub.2) to form sodium titanate (Na.sub.2 TiO.sub.3), manganese (II) titanate (MnTiO.sub.3) and oxygen. The titanate mixture is treated with sodium hydroxide, in the presence of steam, to form sodium titanate, sodium manganate (III), water and hydrogen. The sodium titanate-manganate (III) mixture is treated with water to form sodium manganate (III), titanium dioxide and sodium hydroxide. Sodium manganate (III) and titanium dioxide are recycled following dissolution of sodium hydroxide in water.

Thermochemical generation of hydrogen and oxygen from water

DOEpatents

Robinson, Paul R.; Bamberger, Carlos E.

1982-01-01

A thermochemical cyclic process for the production of hydrogen exploits the reaction between sodium manganate (NaMnO.sub.2) and titanium dioxide (TiO.sub.2) to form sodium titanate (Na.sub.2 TiO.sub.3), manganese (II) titanate (MnTiO.sub.3) and oxygen. The titanate mixture is treated with sodium hydroxide, in the presence of steam, to form sodium titanate, sodium manganate (III), water and hydrogen. The sodium titanate-manganate (III) mixture is treated with water to form sodium manganate (III), titanium dioxide and sodium hydroxide. Sodium manganate (III) and titanium dioxide are recycled following dissolution of sodium hydroxide in water.

Synthesis and characterization of titanium dioxide (TiO2) nanopowder

NASA Astrophysics Data System (ADS)

Munirah, S.; Nadzirah, Sh.; Khusaimi, Z.; Fazlena, H.; Rusop, M.

2018-05-01

Titanium dioxide (TiO2) powder was synthesized via sol-gel technique using Titanium tetraisopropoxide (TTIP) and ethanol as precursors. Acetylacetone, distilled water, polyethylene glycol (PEG) and stabilizers (glacial acetic acid and nitric acid) were then added to the solution. The solution was left for ageing for 24 hours and then dried into powder. The synthesized powders were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA).

Preparation and Optical Properties of Spherical Inverse Opals by Liquid Phase Deposition Using Spherical Colloidal Crystals

NASA Astrophysics Data System (ADS)

Aoi, Y.; Tominaga, T.

2013-03-01

Titanium dioxide (TiO2) inverse opals in spherical shape were prepared by liquid phase deposition (LPD) using spherical colloidal crystals as templates. Spherical colloidal crystals were produced by ink-jet drying technique. Aqueous emulsion droplets that contain polystyrene latex particles were ejected into air and dried. Closely packed colloidal crystals with spherical shape were obtained. The obtained spherical colloidal crystals were used as templates for the LPD. The templates were dispersed in the deposition solution of the LPD, i.e. a mixed solution of ammonium hexafluorotitanate and boric acid and reacted for 4 h at 30 °C. After the LPD process, the interstitial spaces of the spherical colloidal crystals were completely filled with titanium oxide. Subsequent heat treatment resulted in removal of templates and spherical titanium dioxide inverse opals. The spherical shape of the template was retained. SEM observations indicated that the periodic ordered voids were surrounded by titanium dioxide. The optical reflectance spectra indicated that the optical properties of the spherical titanium dioxide inverse opals were due to Bragg diffractions from the ordered structure. Filling in the voids of the inverse opals with different solvents caused remarkable changes in the reflectance peak.

Effect of drying environment on grain size of titanium dioxide nano-powder synthesized via sol-gel method

NASA Astrophysics Data System (ADS)

Zandi, Pegah; Hosseini, Elham; Rashchi, Fereshteh

2018-01-01

Titanium dioxide Nano powder has been synthesized from titanium isopropoxide (TTIP) in chloride media by sol-gel method. In this research, the effect of the drying environment, from air to oven drying at 100 °C, calcination time and temperature on nano TiO2 grain size was investigated. The synthesized powder was analyzed by x-ray diffraction and scanning electron microscope. Based on the results, the powder has been crystallized in anatase and rutile phases, due to different calcination temperatures. At temperatures above 600 °C, the Titanium dioxide nano powder has been crystallized as rutile. The crystalline structure of titanium dioxide nano powder changed because of the different calcination temperatures and time applied. The average particle size of the powder dried in air was larger than the powder dried in oven. The minimum particle size of the powder dried in air was 50 nm and in the oven was 9 nm, observed and calculated Williamson-Hall equation. All in all, with overall increasing of calcination time and temperature the grain size increased. Moreover, in the case of temperature, after a certain temperature, the grain size became constant and didn't change significantly.

Nanomaterial Case Studies: Nanoscale Titanium Dioxide (External Review Draft)

EPA Science Inventory

This draft document presents two case studies of nanoscale titanium dioxide (nano-TiO₂) used (1) to remove arsenic from drinking water and (2) as an active ingredient in topical sunscreen. The draft case studies are organized around a comprehensive environmental asses...

21 CFR 73.575 - Titanium dioxide.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive... and that are listed in this subpart as safe in color additive mixtures for coloring foods, and the...

21 CFR 73.575 - Titanium dioxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive... and that are listed in this subpart as safe in color additive mixtures for coloring foods, and the...

21 CFR 73.575 - Titanium dioxide.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive... and that are listed in this subpart as safe in color additive mixtures for coloring foods, and the...

GAS PHASE SELECTIVE PHOTOXIDATION OF ALCOHOLS USING LIGHT-ACTIVATED TITANIUM DIOXIDE AND MOLECULAR OXYGEN

EPA Science Inventory

Gas Phase Selective Oxidation of Alcohols Using Light-Activated Titanium Dioxide and Molecular Oxygen

Gas phase selective oxidations of various primary and secondary alcohols are studied in an indigenously built stainless steel up-flow photochemical reactor using ultravi...

Photocatalytic oxidation of organic compounds via waveguide-supported titanium dioxide films

NASA Astrophysics Data System (ADS)

Miller, Lawrence W.

A photochemical reactor based on titanium dioxide (TiO2)-coated silica optical fibers was constructed to explore the use of waveguide-supported TiO2 films for photocatalytic oxidation of organic compounds. The reactor was used for the photocatalytic oxidation of 4-chlorophenol in water. It was confirmed that TiO2 films could be securely attached to silica optical fibers. The 4-chlorophenol (100 mumol/L in water) was successfully oxidized on the TiO2 surface when UV light (310 nm--380 nm) was propagated through the fibers to the films. Rates of 4-chlorophenol oxidation and UV light flux to the fibers were measured. The quantum efficiency of 4-chlorophenol oxidation [defined as the change in 4-chlorophenol concentration divided by the UV light absorbed by the catalyst] was determined as a function of TiO2 catalyst film thickness and internal incident angle of propagating UV light. A maximum quantum efficiency of 2.8% was measured when TiO2 film thickness was ca. 80 nm and the maximum internal incident angle of propagating light was 84°. Quantum efficiency increased with increasing internal angle of incidence of propagating light and decreased with TiO2 film thickness. UV-Visible internal reflection spectroscopy was used to determine whether UV light propagated through TiO2-coated silica waveguides in an ATR mode. Propagation of UV light in an ATR mode was confirmed by the similarities between internal reflection spectra of phenolphthalein obtained with uncoated and TiO2-coated silica crystals. Planar silica waveguides coated with TiO2 were employed in a photocatalytic reactor for the oxidation of formic acid (833 mumol/L in water). It was shown that the quantum yield of formic acid oxidation [defined as the moles of formic acid oxidized divided by the moles of UV photons absorbed by the catalyst] on the waveguide-supported TiO2 surface is enhanced when UV light propagates through the waveguides in an ATR mode. A maximum quantum yield of 3.9% was found for formic acid oxidation on silica waveguides. The waveguides were coated with 150 nm of TiO2 and activated with UV light (lambdamax = 360 nm) propagating through the waveguides at an internal incident angle of 68°.

Carbon dioxide conversion over carbon-based nanocatalysts.

PubMed

Khavarian, Mehrnoush; Chai, Siang-Piao; Mohamed, Abdul Rahman

2013-07-01

The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity.

Biosynthesis of titanium dioxide nanoparticles using Bacillus amyloliquefaciens culture and enhancement of its photocatalytic activity for the degradation of a sulfonated textile dye Reactive Red 31.

PubMed

Khan, Razia; Fulekar, M H

2016-08-01

The present study aims at exploiting Bacillus amyloliquefaciens for the biosynthesis of titanium dioxide nanoparticles and also investigates role of bacterial enzymes in the biosynthesis of titanium dioxide nanoparticles. Bacterial synthesized as well as metal doped titanium dioxide nanoparticles were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDAX). Amylase activity (43.37IU) in culture supernatant evinced a potential involvement of extracellular enzyme in TiO2 nanoparticle biosynthesis. Crystallite size of bio-synthesized nanoparticles was found to be in the range of 15.23-87.6nm. FTIR spectroscopy and native-PAGE (Polyacrylamide Gel Electrophoresis) clearly indicated involvement of alpha amylase in biosynthesis of TiO2 nanoparticles and in their stabilization. TEM micrographs of the synthesized titanium dioxide nanoparticles revealed the formation of spherical nanoparticles with a size range of 22.11-97.28nm. Photocatalytic degradation of Reactive Red 31 (RR31) dye was carried out using bio-synthesized TiO2 nanoparticles under UV radiation. Photocatalytic activity of synthesized nanoparticles was enhanced by Ag, La, Zn and Pt doping. Platinum doped TiO2 showed highest potential (90.98%) in RR31 degradation as compared to undoped (75.83%). Copyright © 2016 Elsevier Inc. All rights reserved.

Induced Infiltration of Hole-Transporting Polymer into Photocatalyst for Staunch Polymer-Metal Oxide Hybrid Solar Cells.

PubMed

Park, Jong Hwan; Jung, Youngsuk; Yang, Yooseong; Shin, Hyun Suk; Kwon, Soonchul

2016-10-05

For efficient solar cells based on organic semiconductors, a good mixture of photoactive materials in the bulk heterojunction on the length scale of several tens of nanometers is an important requirement to prevent exciton recombination. Herein, we demonstrate that nanoporous titanium dioxide inverse opal structures fabricated using a self-assembled monolayer method and with enhanced infiltration of electron-donating polymers is an efficient electron-extracting layer, which enhances the photovoltaic performance. A calcination process generates an inverse opal structure of titanium dioxide (<70 nm of pore diameters) providing three-dimensional (3D) electron transport pathways. Hole-transporting polymers was successfully infiltrated into the pores of the surface-modified titanium dioxide under vacuum conditions at 200 °C. The resulting geometry expands the interfacial area between hole- and electron-transport materials, increasing the thickness of the active layer. The controlled polymer-coating process over titanium dioxide materials enhanced photocurrent of the solar cell device. Density functional theory calculations show improved interfacial adhesion between the self-assembled monolayer-modified surface and polymer molecules, supporting the experimental result of enhanced polymer infiltration into the voids. These results suggest that the 3D inverse opal structure of the surface-modified titanium dioxide can serve as a favorable electron-extracting layer in further enhancing optoelectronic performance based on organic or organic-inorganic hybrid solar cell.

Glycerol conversion into value added chemicals over bimetallic catalysts in supercritical carbon dioxide

NASA Astrophysics Data System (ADS)

Hidayati, Luthfiana N.; Sudiyarmanto, Adilina, Indri B.

2017-01-01

Development of alternative energy from biomass encourage the experiments and production of biodiesel lately. Biodiesel industries widely expand because biodiesel as substitute of fossil fuel recognized as promising renewable energy. Glycerol is a byproduct of biodiesel production, which is resulted 10% wt average every production. Meanwhile, carbon dioxide is a gas that is very abundant amount in the atmosphere. Glycerol and carbon dioxide can be regarded as waste, possibly will produce value-added chemical compounds through chemically treated. In this preliminary study, conversion of glycerol and carbon dioxide using bimetallic catalyst Ni-Sn with various catalyst supports : MgO, γ-Al2O3, and hydrotalcite. Catalysts which have been prepared, then physically characterized by XRD, surface area and porosity analysis, and thermal gravity analysis. Catalytic test performance using supercritical carbon dioxide conditions. Furthermore, the products were analyzed by GC. The final product mostly contained of propylene glycol and glycerol carbonate.

Comparative Proteomic Analysis of the Molecular Responses of Mouse Macrophages to Titanium Dioxide and Copper Oxide Nanoparticles Unravels Some Toxic Mechanisms for Copper Oxide Nanoparticles in Macrophages

PubMed Central

Triboulet, Sarah; Aude-Garcia, Catherine; Armand, Lucie; Collin-Faure, Véronique; Chevallet, Mireille; Diemer, Hélène; Gerdil, Adèle; Proamer, Fabienne; Strub, Jean-Marc; Habert, Aurélie; Herlin, Nathalie; Van Dorsselaer, Alain; Carrière, Marie; Rabilloud, Thierry

2015-01-01

Titanium dioxide and copper oxide nanoparticles are more and more widely used because of their catalytic properties, of their light absorbing properties (titanium dioxide) or of their biocidal properties (copper oxide), increasing the risk of adverse health effects. In this frame, the responses of mouse macrophages were studied. Both proteomic and targeted analyses were performed to investigate several parameters, such as phagocytic capacity, cytokine release, copper release, and response at sub toxic doses. Besides titanium dioxide and copper oxide nanoparticles, copper ions were used as controls. We also showed that the overall copper release in the cell does not explain per se the toxicity observed with copper oxide nanoparticles. In addition, both copper ion and copper oxide nanoparticles, but not titanium oxide, induced DNA strands breaks in macrophages. As to functional responses, the phagocytic capacity was not hampered by any of the treatments at non-toxic doses, while copper ion decreased the lipopolysaccharide-induced cytokine and nitric oxide productions. The proteomic analyses highlighted very few changes induced by titanium dioxide nanoparticles, but an induction of heme oxygenase, an increase of glutathione synthesis and a decrease of tetrahydrobiopterin in response to copper oxide nanoparticles. Subsequent targeted analyses demonstrated that the increase in glutathione biosynthesis and the induction of heme oxygenase (e.g. by lovastatin/monacolin K) are critical for macrophages to survive a copper challenge, and that the intermediates of the catecholamine pathway induce a strong cross toxicity with copper oxide nanoparticles and copper ions. PMID:25902355

Preparation of titanium dioxide films by sol-gel route for gas sensors

NASA Astrophysics Data System (ADS)

Schiopu, Vasilica; Matei, Alina; Cernica, Ileana; Podaru, Cecilia

2009-01-01

Semiconductor oxides such as SnO2, TiO2, WO3, ZnO2 etc. have been shown to be useful as gas sensor materials for monitoring various pollutant gases like H2S, NOx, NH3 etc. In this work, we would like to present the preparation of titanium dioxide films for gas sensor application, via the sol-gel technique. The coating solution was prepared by using titanium isopropoxide precursor, which was hydrolyzed with distilled water under the catalytic effect of different acids (HNO3, HCl or CH3COOH). Titanium dioxide films have been deposited using spin coating method and then synthesized at different temperatures. Fourier transform infrared spectroscopy observation has been used to analyze the sol-gel process. The morphology and the structure of the thin films were analyzed.

Nanomaterial Case Studies: Nanoscale Titanium Dioxide in Water Treatment and in Topical Sunscreen (Final)

EPA Science Inventory

EPA announced the availability of the final report, Nanomaterial Case Studies: Nanoscale Titanium Dioxide in Water Treatment and in Topical Sunscreen. This report is a starting point to determine what is known and what needs to be known about selected nanomaterials as par...

Phenotypic and genomic responses to titanium dioxide and cerium oxide nanoparticles in Arabidopsis germinants

EPA Science Inventory

The effects of exposure to two nanoparticles (NPs) -titanium dioxide (nano-titania) and cerium oxide (nano-ceria) at 500 mg NPs L-1 on gene expression and growth in Arabidopsis thaliana germinants were studied using microarrays and phenotype studies. After 12 days post treatment,...

Influence Of Carboxymethyl Cellulose For The Transport Of Titanium Dioxide Nanoparticles In Clean Silica And Mineral-Coated Sands

EPA Science Inventory

The transport properties of titanium dioxide (anatase polymorph) nanoparticles encapsulated by carboxymethyl cellulose (CMC) were evaluated as a function of changes in the solute chemical properties in clean quartz, amorphous aluminum and iron hydroxide-coated sands. While prist...

Reusable photocatalytic titanium dioxide-cellulose nanofiber films

Treesearch

Alexandra Snyder; Zhenyu Bo; Robert Moon; Jean-Christophe Rochet; Lia Stanciu

2013-01-01

Titanium dioxide (TiO2) is a well-studied photocatalyst that is known to break down organic molecules upon ultraviolet (UV) irradiation. Cellulose nanofibers (CNFs) act as an attractive matrix material for the suspension of photocatalytic particles due to their desirable mechanical and optical properties. In this work, TiO2...

NOVEL EMBEDDED CERAMIC ELECTRODE SYSTEM TO ACTIVATE NANOSTRUCTURED TITANIUM DIOXIDE FOR DEGRADATION OF MTBE

EPA Science Inventory

A novel reactor combining a flame-deposited nanostructured titanium dioxide film and a set of embedded ceramic electrodes was designed, developed and tested for degradation of methyl tert-butyl ether (MTBE) in water. On applying a voltage to the ceramic electrodes, a surface coro...

Nano Titanium Dioxide Environmental Matters: State of the Science Literature Review

EPA Science Inventory

The purpose of this report is to compile and summarize currently-available information pertaining to the manufacturing, processing, use, and end-of-life for nanoscale titanium dioxide (nano-TiO₂). The focus of the report is to identify, summarize, and present informat...

In Vitro Phototoxicity and Hazard Identification of Nano-scale Titanium Dioxide

EPA Science Inventory

Nano-titanium dioxide (nano-Ti02) catalyzes many reactions under UV radiation and is hypothesized to cause phototoxicity. A human-derived line of retinal pigment epithelial cells (ARPE-19) was treated with six different samples of nano-Ti02 and exposed to UVA radiation. The Ti02 ...

Impact of natural organic matter on particle behavior and phototoxicity of titanium dioxide nanoparticles

EPA Science Inventory

Due to their inherent phototoxicity and inevitable environmental release, titanium dioxide nanoparticles (nano-TiO2) are increasingly studied in the field of aquatic toxicology. One of the particular interests is the interactions between nano-TiO2 and natural organic matter (NOM)...

Toxicity Assessment of Six Titanium Dioxide Nanoparticles in Human Epidermal Keratinocytes

EPA Science Inventory

Toxicity Assessment of Six Titanium Dioxide Nanoparticles in Human Epidermal Keratinocytes Nanoparticle uptake in cells may be an important determinant of their potential cytotoxic and inflammatory effects. Six commercial TiO2 NP (A=Alfa Aesar,10nm, A*=Alfa Aesar 32nm, B=P25 27...

Silica-Supported Catalyst for Enantioselective Arylation of Aldehydes under Batch and Continuous-Flow Conditions.

PubMed

Watanabe, Satoshi; Nakaya, Naoyuki; Akai, Junichiro; Kanaori, Kenji; Harada, Toshiro

2018-05-04

A silica-supported 3-aryl H 8 -BINOL-derived titanium catalyst exhibited high performance in the enantioselective arylation of aromatic aldehydes using Grignard and organolithium reagents not only under batch conditions but also under continuous-flow conditions. Even with a simple pipet reactor packed with the heterogeneous catalyst, the enantioselective production of chiral diarylmethanols could be achieved through a continuous introduction of aldehydes and mixed titanium reagents generated from the organometallic precursors. The pipet reactor could be used repeatedly in different reactions without appreciable deterioration of the activity.

Photodegradation of organic pollutants using N-titanium oxide catalyst.

PubMed

Shinde, S S; Bhosale, C H; Rajpure, K Y

2014-12-01

Photoelectrocatalytic degradation of typical aromatic compounds with persistent reaction rate is studied using thin layers of N-titanium dioxide deposited on transparent and conducting glass substrates. Backside illuminated flow-through parallel plate photoelectrochemical reactors is used and electrical bias for suppressing charge carrier recombination is applied externally. The degradation experiments are performed under solar irradiation with the conditions aimed at reducing contaminant concentrations to maximal tolerated levels as specified under environmental regulations. From the observed COD-time relations, rate constants normalized to unit volume and photocurrent (kinetic parameters), characterizing the efficiency of the electrochemical oxidation process involving photogenerated valence band holes or their immediate reaction products, are calculated and compared to the decrease of optical extinction of the solutions. The parameters for salicylic acid, 4-chlorophenol, benzoic acid and oxalic acid are found to decrease as the main absorption peaks of these substances diminish in due course of degradation reaction. In order to realize a complete mineralization of such compounds, which should be an ultimate aim of water purification, COD and TOC is analyzed. Copyright © 2014 Elsevier B.V. All rights reserved.

The formation of titanium dioxide crystallite nanoparticles during activation of PAN nanofibers containing titanium isopropoxide

NASA Astrophysics Data System (ADS)

Mehrpouya, Fahimeh; Tavanai, Hossein; Morshed, Mohammad; Ghiaci, Mehran

2012-08-01

Activated carbon (AC) can act as an important carrier for TiO2 nanoparticles. TiO2 nanoparticle can be fabricated by the hydrolysis and condensation of titanium alkoxides like titanium isopropoxide. This study showed that the formation of titanium dioxide crystallite nanoparticle during activation of PAN nanofibers containing titanium isopropoxide leads to the formation of mainly anatase crystal TiO2 nanoparticle in AC nanofibers, with a good dispersion in both the longitude and cross section of nanofibers. The TiO2 crystallite size lies in the range of 7.3-11.3 nm. The dispersion of TiO2 nanoparticles in the matrix of AC nanofibers is far superior to the direct mixing of TiO2 nanoparticles in the original electrospinning solution.

Electrically conductive ceramic powders

NASA Astrophysics Data System (ADS)

Lu, Yanxia

1999-11-01

Electrically conductive ceramic powders were investigated in this project. There are three ways to produce those materials. The first is doping alkali metal into the titanium dioxides in an inert or reducing atmosphere. The second is reducing un-doped titanium dioxide, forming a non-stoichiometric composition in a hydrogen atmosphere. The third is to coat a conductive layer, reduced titanium dioxide, on an insulating core such as alumina. Highly conductive powders have been produced by all these processes. The conductivity of powder compacts ranged between 10-2 and 10° S/cm. A novel doping process was developed. All samples were doped by a solid-vapor reaction instead of a solid state reaction. Titanium dioxide was doped with alkali metals such as Na or Li in this study. The alkali metal atom contributes an electron to the host material (TiO2), which then creates Ti 3+ ion. The conductivity was enhanced by creating the donor level due to the presence of these Ti3+ ions. The conductivity of those alkali doped titanium oxides was dependent on the doping level and charge mobility. Non-stoichiometric titanium oxides were produced by reduction of titanium dioxide in a hydrogen atmosphere at 800°C to 1000°C for 2 to 6 hours. The reduced titanium oxides showed better stability with respect to conductivity at ambient condition when compared with the Na or Li doped samples. Conductive coatings were prepared by coating titanium precursors on insulating core materials like SiO2, Al2O3 or mica. The titania coating was made by hydrolysis of titanyl sulfate (TiOSO 4) followed by a reduction procedure to form reduced titanium oxide. The reduced titanium oxides are highly conductive. A uniform coating of titanium oxides on alumina cores was successfully produced. The conductivity of coated powder composites was a function of coating quantity and hydrolysis reaction temperature. The conductivity of the powder as a function of structure, composition, temperature, frequency and moisture was studied. Three classifications of structure were identified for alkali-doped titanium oxides: (1) Pure titanium dioxide phase with alkali ions located in interstitial positions. (2) The titanium bronze phases. (3) Alkali-doped titanium oxides. Highly conductive powders were obtained in the first and second classifications with conductivity of 10-2 to 10° S/cm. Materials in the third classification had poor conductivity below 10-3 S/cm. The conductivity of a powder was determined mainly by the grain conductivity and the grain contact conductivity. The present results of impedance spectroscopy suggested that the grain contact resistance was a major factor of the electrical resistance of the samples. The aging effect at different moisture conditions was also caused by an increase of the contact resistance. Both sodium-doped and reduced titanium oxides showed re-oxidation at elevated temperature (above 140°C) in air, which is most probably caused by oxidizing the Ti3+ ions under those conditions. Lithium doped titanium oxides did not show this re-oxidation at temperatures up to 200°C. Theoretical models were applied to describe the effects of porosity, contact configuration and grain surface on conductivity of powder compacts. Percolation theory was used in the present study to demonstrate the effect of mixtures of conductive and non-conductive powders, which is one of applications for conductive ceramic powders when they are used as filler materials in paper, paints or plastics.

Mineral of the month: titanium

USGS Publications Warehouse

Gambogi, Joseph

2004-01-01

From paint to airplanes, titanium is important in a number of applications. Commercial production comes from titanium-bearing ilmenite, rutile and leucoxene (altered ilmenite). These minerals are used to produce titanium dioxide pigment, as well as an assortment of metal and chemical products.

Adsorption performance of titanium dioxide (TiO2) coated air filters for volatile organic compounds.

PubMed

Zhong, Lexuan; Lee, Chang-Seo; Haghighat, Fariborz

2012-12-01

The photocatalytic oxidation (PCO) technology as an alternative method for air purification has been studied for decades and a variety of PCO models indicate that the adsorption of reactants on the catalyst surface is one of the major physical and chemical processes occurring at a heterogeneous photocatalytic reaction. However, limited study explored the adsorption effect of a photocatalyst. This study carried out a systematic evaluation of adsorption performance of titanium dioxide (TiO(2)) coated fiberglass fibers (FGFs), TiO(2) coated carbon cloth fibers (CCFs), and original CCFs air filters at various relative humidity conditions for nine volatile organic compounds. TiO(2)/FGFs, TiO(2)/CCFs, and CCFs were characterized by SEM for morphology and N(2) adsorption isotherm for BET surface area and pore structure. A bench-scale adsorption test setup was constructed and adsorption tests were performed at various relative humidity conditions and four different injected concentrations for each compound. The isothermal adsorption curves at low concentration levels were obtained and they were well described by Langmuir isotherm model. It was noticed that there were significant differences between the adsorption behaviors and photocatalytic activities of TiO(2)/FGFs and TiO(2)/CCFs. It was concluded that adsorption performance is closely related to the characteristics of substrates and therefore, the development of a substrate with high adsorption ability is a promising trend for improving the performance of the UV-PCO technology. Copyright © 2012 Elsevier B.V. All rights reserved.

Degradation of metaldehyde in water by nanoparticle catalysts and powdered activated carbon.

PubMed

Li, Zhuojun; Kim, Jong Kyu; Chaudhari, Vrushali; Mayadevi, Suseeladevi; Campos, Luiza C

2017-07-01

Metaldehyde, an organic pesticide widely used in the UK, has been detected in drinking water in the UK with a low concentration (<1 μg L -1 ) which is still above the European and UK standard requirements. This paper investigates the efficiency of four materials: powdered activated carbon (PAC) and carbon-doped titanium dioxide nanocatalyst with different concentrations of carbon (C-1.5, C-40, and C-80) for metaldehyde removal from aqueous solutions by adsorption and oxidation via photocatalysis. PAC was found to be the most effective material which showed almost over 90% removal. Adsorption data were well fitted to the Langmuir isotherm model, giving a q m (maximum/saturation adsorption capacity) value of 32.258 mg g -1 and a K L (Langmuir constant) value of 2.013 L mg -1 . In terms of kinetic study, adsorption of metaldehyde by PAC fitted well with a pseudo-second-order equation, giving the adsorption rate constant k 2 value of 0.023 g mg -1  min -1 , implying rapid adsorption. The nanocatalysts were much less effective in oxidising metaldehyde than PAC with the same metaldehyde concentration and 0.2 g L -1 loading concentration of materials under UV light; the maximum removal achieved by carbon-doped titanium dioxide (C-1.5) nanocatalyst was around 15% for a 7.5 ppm metaldehyde solution. Graphical abstract ᅟ.

Thermochemical generation of hydrogen and oxygen from water. [NaMnO/sub 2/ and TiO/sub 2/

DOEpatents

Robinson, P.R.; Bamberger, C.E.

1980-02-08

A thermochemical cyclic process for the production of hydrogen exploits the reaction between sodium manganate (NaMnO/sub 2/) and titanium dioxide (TiO/sub 2/) to form sodium titanate (Na/sub 2/TiO/sub 3/), manganese (II) titanate (MnTiO/sub 3/) and oxygen. The titanate mixture is treated with sodium hydroxide, in the presence of steam, to form sodium titanate, sodium manganate (III), water and hydrogen. The sodium titanate-manganate (III) mixture is treated with water to form sodium manganate (III), titanium dioxide and sodium hydroxide. Sodium manganate (III) and titanium dioxide are recycled following dissolution of sodium hydroxide in water.

Titanium compounds as catalysts of higher alpha-olefin-based super-high-molecular polymers synthesis

NASA Astrophysics Data System (ADS)

Konovalov, K. B.; Kazaryan, M. A.; Manzhay, V. N.; Vetrova, O. V.

2016-01-01

The synthesis of polymers of 10 million or more molecular weight is a difficult task even in a chemical lab. Higher α-olefin-based polymer agents of such kind have found a narrow but quite important niche, the reduction of drag in the turbulent flow of hydrocarbon fluids such as oil and oil-products. In its turn, searching for a catalytic system capable to produce molecules of such a high length and to synthesize polymers of a low molecular-mass distribution is part of a global task of obtaining a high-quality product. In this paper we had observed a number of industrial catalysts with respect to their suitability for higher poly-α- olefins synthesis. A number samples representing copolymers of 1-hexene with 1-decene obtained on a previous generation catalyst, a microsphere titanium chloride catalytic agent had been compared to samples synthesized using a titanium-magnesium catalyst both in solution and in a polymer medium.

Iron-catalyzed hydrogenation of bicarbonates and carbon dioxide to formates.

PubMed

Zhu, Fengxiang; Zhu-Ge, Ling; Yang, Guangfu; Zhou, Shaolin

2015-02-01

The catalytic hydrogenation of carbon dioxide and bicarbonate to formate has been explored extensively. The vast majority of the known active catalyst systems are based on precious metals. Herein, we describe an effective, phosphine-free, air- and moisture-tolerant catalyst system based on Knölker's iron complex for the hydrogenation of bicarbonate and carbon dioxide to formate. The catalyst system can hydrogenate bicarbonate at remarkably low hydrogen pressures (1-5 bar). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improvement of water resistance and dimensional stability of wood through titanium dioxide coating

Treesearch

Qingfeng Sun; Haipeng Yu; Yixing Liu; Jian Li; Yun Lu; John F. Hunt

2010-01-01

Moisture absorption and dimensional distortion are the major drawbacks of wood utilization as building material. In this study, poplar wood coated with a thin layer of titanium dioxide (TiO2) was prepared by the cosolvent-controlled hydrothermal method. Subsequently, its moisture absorption and dimensional stability were examined. Scanning...

Effects of Material Properties on Sedimentation and Aggregation of Titanium Dioxide Nanoparticles of Anatase and Rutile in the Aqueous Phase

EPA Science Inventory

This study investigated the sedimentation and aggregation kinetics of titanium dioxide (TiO2) nanoparticles with varying material properties (i.e., crystallinity, morphology, and chemical compositions). Used in the study were various types of commercially available TiO2 nanoparti...

Photocatalytic ROS production and phototoxicity of titanium dioxide nanoparticles is dependent on solar UV radiation spectrum

EPA Science Inventory

Generation of reactive oxygen species (ROS) by titanium dioxide nanoparticles (nano-TiO2) and its consequent phototoxicity to Daphnia magna were measured under different solar UV radiation spectrum by applying a series of optical filters in a solar simulator. Removing UVB (280-32...

Effect of Treatment Media on the Agglomeration of Titanium Dioxide Nanoparticles: Impact on Genotoxicity, Cellular Interaction, and Cell Cycle

EPA Science Inventory

ABSTRACT The widespread use of titanium dioxide (TiO2) nanoparticles in consumer products increases the probability of exposure to humans and the environment. Although TiO2 nanoparticles have been shown to induce DNA damage (comet assay) and chromosome damage (micronucleus ass...

Development of silver/titanium dioxide/chitosan adipate nanocomposite as an antibacterial coating for fruit storage

USDA-ARS?s Scientific Manuscript database

A novel nanocomposite of silver/titanium dioxide/chitosan adipate (Ag/TiO2/CS) was developed through photochemical reduction using a chitosan adipate template. Chitosan served as a reducing agent for the metal ions, and anchored metal ions by forming Ag–N coordination bonds and electrostatic attract...

Effect of low Fe3+ doping on characteristics, sonocatalytic activity and reusability of TiO2 nanotubes catalysts for removal of Rhodamine B from water.

PubMed

Pang, Yean Ling; Abdullah, Ahmad Zuhairi

2012-10-15

Fe-doped titanium dioxide (TiO(2)) nanotubes were prepared using sol-gel followed by hydrothermal methods and characterized using various methods. The sonocatalytic activity was evaluated based on oxidation of Rhodamine B under ultrasonic irradiation. Iron ions (Fe(3+)) might incorporate into the lattice and intercalated in the interlayer spaces of TiO(2) nanotubes. The catalysts showed narrower band gap energies, higher specific surface areas, more active surface oxygen vacancies and significantly improved sonocatalytic activity. The optimum Fe doping at Fe:Ti=0.005 showed the highest sonocatalytic activity and exceeded that of un-doped TiO(2) nanotubes by a factor of 2.3 times. It was believed that Fe(3+) doping induced the formation of new states close to the valence band and conduction bands and accelerated the separation of charge carriers. Leached Fe(3+) could catalyze Fenton-like reaction and led to an increase in the hydroxyl radical (OH) generation. Fe-doped TiO(2) nanotubes could retain high degradation efficiency even after being reused for 4 cycles with minimal loss of Fe from the surface of the catalyst. Copyright © 2012 Elsevier B.V. All rights reserved.

The enhancing performance of (Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.90}Zr{sub 0.10})O{sub 3} ceramics by tuning anatase–rutile phase structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, Xiaolian, E-mail: chaoxl@snnu.edu.cn; Wang, Juanjuan; Wang, Zhongming

2016-04-15

Graphical abstract: Titanium dioxide (TiO{sub 2}) with different phase structure had interesting influence on the crystal structure, microstructure, the sintering temperature and electrical properties. - Highlights: • BCZT ceramics were prepared using either anatase or rutile structures as Ti source. • Orthorhombic and tetragonal mixture structure was exhibited by adjusting Ti source. • The optimal properties were observed in BCZT ceramics with rutile titanium dioxide. - Abstract: To research effect of raw materials TiO{sub 2} with the phase structures on the crystal structure, microstructure and electrical properties of lead-free (Ba{sub 0.85}Ca{sub 0.15})(Ti{sub 0.90}Zr{sub 0.10})O{sub 3} (BCZT) ceramics, BCZT ceramics usingmore » either anatase or rutile as Ti source were synthesized by solid-state reaction. Titanium dioxide (TiO{sub 2}) with anatase/rutile phase structures had interesting influence on the crystal structure, microstructure and the sintering temperature by the X-ray diffraction and SEM, which also played an important role in improved electrical properties. The BCZT ceramics with rutile titanium dioxide demonstrated optimal piezoelectric and dielectric properties: d{sub 33} = 590 pC/N, k{sub p} = 0.46, ε{sub r} = 2810, tanδ = 0.014 and T{sub c} = 91 °C, which was obviously superior to BCZT ceramics with anatase titanium dioxide.« less

Pt deposited TiO2 catalyst fabricated by thermal decomposition of titanium complex for solar hydrogen production

NASA Astrophysics Data System (ADS)

Truong, Quang Duc; Le, Thanh Son; Ling, Yong-Chien

2014-12-01

C, N codoped TiO2 catalyst has been synthesized by thermal decomposition of a novel water-soluble titanium complex. The structure, morphology, and optical properties of the synthesized TiO2 catalyst were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the Pt deposited TiO2 catalysts synthesized at different temperatures was evaluated by means of hydrogen evolution reaction under both UV-vis and visible light irradiation. The investigation results reveal that the photocatalytic H2 evolution rate strongly depended on the crystalline grain size as well as specific surface area of the synthesized catalyst. Our studies successfully demonstrate a simple method for the synthesis of visible-light responsive Pt deposited TiO2 catalyst for solar hydrogen production.

DEVELOPMENT OF IMPROVED TITANIUM ORGANIC COMPOUNDS FOR USE AS HYDRAULIC FLUIDS

DTIC Science & Technology

HYDRAULIC FLUIDS, *METALORGANIC COMPOUNDS, *TITANATES, *TITANIUM COMPOUNDS, ALKYL RADICALS, CATALYSTS , CHLORIDES, COMPLEX COMPOUNDS, FLUIDS, PHOSPHORIC ACIDS, PROPYL RADICALS, VISCOSITY, ZINC COMPOUNDS

Synthesis and characterization of TiO2 loaded cashew nut shell activated carbon and photocatalytic activity on BG and MB dyes under sunlight radiation

NASA Astrophysics Data System (ADS)

Ragupathy, S.; Raghu, K.; Prabu, P.

2015-03-01

Synthesis of titanium dioxide (TiO2) nanoparticles and TiO2 loaded cashew nut shell activated carbon (TiO2/CNSAC) had been undertaken using sol-gel method and their application in BG and MB dyes removal under sunlight radiation has been investigated. The synthesized photocatalysts were characterized by X-ray diffraction analysis (XRD), Fourier infra-red spectroscopy (FT-IR), UV-Vis-diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX). The various experimental parameters like amount of catalyst, contact time for efficient dyes degradation of BG and MB were concerned in this study. Activity measurements performed under solar irradiation has shown good results for the photodegradation of BG and MB in aqueous solution. It was concluded that the higher photocatalytic activity in TiO2/CNSAC was due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst. The kinetic data were also described by the pseudo-first-order and pseudo-second-order kinetic models.

Conversion of NO with a catalytic packed-bed dielectric barrier discharge reactor

NASA Astrophysics Data System (ADS)

Xu, CAO; Weixuan, ZHAO; Renxi, ZHANG; Huiqi, HOU; Shanping, CHEN; Ruina, ZHANG

2017-11-01

This paper discusses the conversion of nitric oxide (NO) with a low-temperature plasma induced by a catalytic packed-bed dielectric barrier discharge (DBD) reactor. Alumina oxide (Al2O3), glass (SiO2) and zirconium oxide (ZrO2), three different spherical packed materials of the same size, were each present in the DBD reactor. The NO conversion under varying input voltage and specific energy density, and the effects of catalysts (titanium dioxide (TiO2) and manganese oxide (MnO x ) coated on Al2O3) on NO conversion were investigated. The experimental results showed that NO conversion was greatly enhanced in the presence of packed materials in the reactor, and the catalytic packed bed of MnO x /Al2O3 showed better performance than that of TiO2/Al2O3. The surface and crystal structures of the materials and catalysts were characterized through scanning electron microscopy analysis. The final products were clearly observed by a Fourier transform infrared spectrometer and provided a better understanding of NO conversion.

Titanium Dioxide Modulation of the Contractibility of Visceral Smooth Muscles In Vivo

NASA Astrophysics Data System (ADS)

Tsymbalyuk, Olga V.; Naumenko, Anna M.; Rohovtsov, Oleksandr O.; Skoryk, Mykola A.; Voiteshenko, Ivan S.; Skryshevsky, Valeriy A.; Davydovska, Tamara L.

2017-02-01

Electronic scanning microscopy was used in the work to obtain the image and to identify the sizes of titanium dioxide (TiO2) nanoparticles 21 ± 5 nm. The qualitative and quantitative elemental analysis of the preparations of the caecum, antrum, myometrium, kidneys, and lungs of the rats, burdened with titanium dioxide, was also performed. It was established using the tenzometric method in the isometric mode that the accumulation of titanium dioxide in smooth muscles of the caecum resulted in the considerable, compared to the control, increase in the frequency of their spontaneous contractions, the decrease in the duration of the contraction-relaxation cycle, and the decrease in the indices of muscle functioning efficiency (the index of contractions in Montevideo units (MU) and the index of contractions in Alexandria units (AU)). In the same experimental conditions, there was not the increase, but the decrease in the frequency of spontaneous contractions, the duration of the contraction-relaxation cycle, and the increase in MU and AU indices in the smooth muscles of myometrium (in the group of rats, burdened with TiO2 for 30 days). It was also determined that TiO2 modulates both the mechanisms of the input of extracellular Ca2+ ions and the mechanisms of decreasing the concentration of these cations in smooth muscle cells of the caecum during the generation of the high potassium contraction. In these conditions, there is a considerable increase in the normalized maximal velocity of the contraction phase and the relaxation phase. It was demonstrated in the work that titanium dioxide also changes the cholinergic excitation in these muscles. The impact of titanium dioxide in the group of rats, burdened with TiO2, was accompanied with a considerable impairment of the kinetics of forming the tonic component of the oxytocin-induced contraction of the smooth muscles of myometrium.

In vitro assessment of artifacts induced by titanium, titanium-zirconium and zirconium dioxide implants in cone-beam computed tomography.

PubMed

Sancho-Puchades, Manuel; Hämmerle, Christoph H F; Benic, Goran I

2015-10-01

The aim of this study was to test whether or not the intensity of artifacts around implants in cone-beam computed tomography (CBCT) differs between titanium, titanium-zirconium and zirconium dioxide implants. Twenty models of a human mandible, each containing one implant in the single-tooth gap position 45, were cast in dental stone. Five test models were produced for each of the following implant types: titanium 4.1 mm diameter (Ti4.1 ), titanium 3.3 mm diameter (Ti3.3 ), titanium-zirconium 3.3 mm diameter (TiZr3.3 ) and zirconium dioxide 3.5-4.5 mm diameter (ZrO3.5-4.5 ) implants. For control purposes, three models without implants were produced. Each model was scanned using a CBCT device. Gray values (GV) were recorded at eight circumferential positions around the implants at 0.5 mm, 1 mm and 2 mm from the implant surface (GVT est ). GV were assessed in the corresponding volumes of interest (VOI) in the control models without implants (GVC ontrol ). Differences of gray values (ΔGV) between GVT est and GVC ontrol were calculated as percentages. One-way ANOVA and post hoc tests were applied to detect differences between implant types. Mean ΔGV for ZrO3.5-4.5 presented the highest absolute values, generally followed by TiZr3.3 , Ti4.1 and Ti3.3 implants. The differences of ΔGV between ZrO3.5-4.5 and the remaining groups were statistically significant in the majority of the VOI (P ≤ 0.0167). ΔGV for TiZr3.3 , Ti4.1 and Ti3.3 implants did not differ significantly in the most VOI. For all implant types, ΔGV showed positive values buccally, mesio-buccally, lingually and disto-lingually, whereas negative values were detected mesially and distally. Zirconium dioxide implants generate significantly more artifacts as compared to titanium and titanium-zirconium implants. The intensity of artifacts around zirconium dioxide implants exhibited in average the threefold in comparison with titanium implants. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Highly selective plasma-activated copper catalysts for carbon dioxide reduction to ethylene

DOE PAGES

Mistry, Hemma; Varela, Ana Sofia; Bonifacio, Cecile S.; ...

2016-06-30

There is an urgent need to develop technologies that use renewable energy to convert waste products such as carbon dioxide into hydrocarbon fuels. Carbon dioxide can be electrochemically reduced to hydrocarbons over copper catalysts, although higher efficiency is required. We have developed oxidized copper catalysts displaying lower overpotentials for carbon dioxide electroreduction and record selectivity towards ethylene (60%) through facile and tunable plasma treatments. Herein we provide insight into the improved performance of these catalysts by combining electrochemical measurements with microscopic and spectroscopic characterization techniques. Operando X-ray absorption spectroscopy and cross-sectional scanning transmission electron microscopy show that copper oxides aremore » surprisingly resistant to reduction and copper + species remain on the surface during the reaction. Furthermore, our results demonstrate that the roughness of oxide-derived copper catalysts plays only a partial role in determining the catalytic performance, while the presence of copper + is key for lowering the onset potential and enhancing ethylene selectivity.« less

40 CFR 90.329 - Catalyst thermal stress test.

Code of Federal Regulations, 2010 CFR

2010-07-01

....3 Carbon Dioxide 3.8 Water Vapor 10 Sulfer dioxide 20 Oxides of nitrogen 280 Hydrogen 3500 Hydrocarbon* 4000 Nitrogen = Balance * Propylene/propane ratio = 2/1. (c) Phase 2 engines. The catalyst...

40 CFR 90.329 - Catalyst thermal stress test.

Code of Federal Regulations, 2014 CFR

2014-07-01

....3 Carbon Dioxide 3.8 Water Vapor 10 Sulfer dioxide 20 Oxides of nitrogen 280 Hydrogen 3500 Hydrocarbon* 4000 Nitrogen = Balance * Propylene/propane ratio = 2/1. (c) Phase 2 engines. The catalyst...

40 CFR 90.329 - Catalyst thermal stress test.

Code of Federal Regulations, 2011 CFR

2011-07-01

....3 Carbon Dioxide 3.8 Water Vapor 10 Sulfer dioxide 20 Oxides of nitrogen 280 Hydrogen 3500 Hydrocarbon* 4000 Nitrogen = Balance * Propylene/propane ratio = 2/1. (c) Phase 2 engines. The catalyst...

40 CFR 90.329 - Catalyst thermal stress test.

Code of Federal Regulations, 2012 CFR

2012-07-01

....3 Carbon Dioxide 3.8 Water Vapor 10 Sulfer dioxide 20 Oxides of nitrogen 280 Hydrogen 3500 Hydrocarbon* 4000 Nitrogen = Balance * Propylene/propane ratio = 2/1. (c) Phase 2 engines. The catalyst...

40 CFR 90.329 - Catalyst thermal stress test.

Code of Federal Regulations, 2013 CFR

2013-07-01

....3 Carbon Dioxide 3.8 Water Vapor 10 Sulfer dioxide 20 Oxides of nitrogen 280 Hydrogen 3500 Hydrocarbon* 4000 Nitrogen = Balance * Propylene/propane ratio = 2/1. (c) Phase 2 engines. The catalyst...

Effect of TiO2 calcination temperature on the photocatalytic oxidation of gaseous NH3.

PubMed

Wu, Hongmin; Ma, Jinzhu; Zhang, Changbin; He, Hong

2014-03-01

Carbon-modified titanium dioxide (TiO2) was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation (PCO) of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400°C had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range (< 300°C). However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400°C contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

L-Lactide Ring-Opening Polymerization with Tris(acetylacetonate)Titanium(IV) for Renewable Material.

PubMed

Kim, Da Hee; Yoo, Ji Yun; Ko, Young Soo

2016-05-01

A new Ti-type of catalyst for L-lactide polymerization was synthesized by reaction of titanium(IV) isopropoxide (TTIP) with acetylacetone (AA). Moreover, PLA was prepared by the bulk ring-opening polymerization using synthesized Ti catalyst. Polymerization behaviors were examined depending on monomer/catalyst molar ratio, polymerization temperature and time. The structure of synthesized catalysts was verified with FT-IR and 1H NMR and the properties of poly(L-lactide) (PLLA) were examined by GPC, DSC and FT-IR. There existed about 30 minutes of induction time at the monomer/catalyst molar ratio of 300. The molecular weight (MW) increased as monomer/catalyst molar ratio increased. The MW increased almost linearly as polymerization progressed. Increasing polymerization temperature increased the molecular weight of PLLA as well as monomer/catalyst molar ratio. The melting point (T(m)) of polymers was in the range of 142 to 167 degrees C. Lower T(m) was expected to be resulted from relatively lower molecular weight.

Photocatalytic destruction of chlorinated solvents in water with solar energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pacheco, J.E.; Prairie, M.R.; Yellowhorse, L.

1993-08-01

Sandia National Laboratories and the National Renewable Energy Laboratory are developing a photocatalytic process to destroy organic contaminants in water. Tests with common water pollutants have been conducted at Sandia's Solar Thermal Facility using a near commercial scale, single-axis tracking parabolic trough system with a glass pipe reactor mounted at its focus. Experiments at this scale provide verification of laboratory studies and allow examination of design and operation issues at a real-lifescale. The catalyst, titanium dioxide (TiO[sub 2]), is a harmless material found in paint, cosmetics, and toothpaste. Experiments were conducted to determine the effects of key process parameters onmore » destruction rates of chlorinated organic compounds that are common water pollutants. This paper summarizes the engineering-scale results of these experiments and analyses.« less

Photocatalytic oxidation mechanism of alkanes in contact with titanium dioxide

NASA Technical Reports Server (NTRS)

Formenti, M.; Juillet, F.; Teichner, S. J.

1977-01-01

Isobutane was photooxidized on titanium dioxide between -16 and +180 C in tertiary butanol and acetone. The formation of tertiary butanol preceded the formation of acetone. Above 20 C the latter compound became clearly predominant. The reaction kinetics obeyed a steady state model of oxygen chemisorption with the involvement of isobutane in the physisorbed phase.

Germination and early plant development of ten plant species exposed to titanium dioxide and cerium oxide nanoparticles

EPA Science Inventory

Ten agronomic plant species were exposed to different concentrations of nano titanium dioxide (nTiO2) or nano cerium oxide (nCeO2) (0, 250, 500 and 1000 mg/L) to examine potential effects on germination and early seedling development. We modified a standard test protocol develop...

Effect of Coating and Packaging Materials on Photocatalytic and Antimicrobial Activities of Titanium Dioxide Nanoparticles

USDA-ARS?s Scientific Manuscript database

Food safety or foodborne pathogen contamination is a major concern in food industry. Titanium dioxide (TiO2) is a photocatalyst and can inactivate a wide spectrum of microorganisms under UV illumination. There is significant interest in the development of TiO2-coated or –incorporated food packaging ...

Investigation of plasma dynamics during the growth of amorphous titanium dioxide thin films

NASA Astrophysics Data System (ADS)

Kim, Jin-Soo; Jee, Hyeok; Yu, Young-Hun; Seo, Hye-Won

2018-06-01

We have grown amorphous titanium dioxide thin films by reactive DC sputtering method using a different argon/oxygen partial pressure at a room temperature. The plasma dynamics of the process, reactive and sputtered gas particles was investigated via optical emission spectroscopy. We then studied the correlations between the plasma states and the structural/optical properties of the films. The growth rate and morphology of the titanium dioxide thin films turned out to be contingent with the population and the energy profile of Ar, O, and TiO plasma. In particular, the films grown under energetic TiO plasma have shown a direct band-to-band transition with an optical energy band gap up to ∼4.2 eV.

Photocatalytic destruction of automobile exhaust emissions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaviranta, P.D.; Peden, C.H.F.

1996-10-01

Hydrocarbons, carbon monoxide, and nitrogen oxides contained in automobile exhaust emissions are among the major atmospheric air pollutants. During the first few minutes of a cold start of the engine, the emission levels of unburned hydrocarbon and CO pollutants are very high due to the inefficiency of the cold engine and the poor activity of the catalysts lower temperatures. Therefore, it is necessary to provide an alternative approach to deal with this specific problem in order to meet near-term regulatory requirements. Our approach has been to use known photocatalytic reactions obtainable on semiconducting powders such as titanium dioxide. In thismore » presentation we describe our recent studies aimed at the photocatalytic reduction of unburned hydrocarbons and carbon monoxide in automobile exhaust emissions. Our results demonstrate the effective destruction of propylene into water and carbon dioxide. The conversion was found to be dependent on the propylene flow rate. The reaction rate was studied as a function of time, humidity and temperature. The effect of the power of the UV source on conversion will also be presented.« less

Bronchiolitis obliterans organizing pneumonia due to titanium nanoparticles in paint.

PubMed

Cheng, Tong-Hong; Ko, Fu-Chang; Chang, Junn-Liang; Wu, Kuo-An

2012-02-01

We present a case of a 58-year-old man who experienced Bronchiolitis obliterans organizing pneumonia after a 3-month exposure to polyester powder paint. Mineralogical analysis by transmission electron microscopy of a pulmonary sample and the polyester powder paint he was exposed to showed the presence of titanium dioxide nanoparticles in both. We suggest that exposure to titanium dioxide nanoparticles should be added to the etiology of Bronchiolitis obliterans organizing pneumonia. Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Effects of porous films on the light reflectivity of pigmentary titanium dioxide particles

NASA Astrophysics Data System (ADS)

Liang, Yong; Qiao, Bing; Wang, Tig-Jie; Gao, Han; Yu, Keyi

2016-11-01

The light reflectivity of the film-coated titanium dioxide particles (TiO2) as a function of the film refractive index was derived and calculated using a plane film model. For the refractive index in the range of 1.00-2.15, the lower the film refractive index is, the higher is the light reflectivity of the film. It is inferred that the lower apparent refractive index of the porous film resulted in the higher reflectivity of light, i.e., the higher hiding power of the titanium dioxide particles. A dense film coating on TiO2 particles with different types of oxides, i.e., SiO2, Al2O3, MgO, ZnO, ZrO2, TiO2, corresponding to different refractive indices of the film from 1.46 to 2.50, was achieved, and the effects of refractive index on the hiding power from the model prediction were confirmed. Porous film coating of TiO2 particles was achieved by adding the organic template agent triethanolamine (TEA). The hiding power of the coated TiO2 particles was increased from 88.3 to 90.8 by adding the TEA template to the film coating (5-20 wt%). In other words, the amount of titanium dioxide needed was reduced by approximately 10% without a change in the hiding power. It is concluded that the film structure coated on TiO2 particle surface affects the light reflectivity significantly, namely, the porous film exhibits excellent performance for pigmentary titanium dioxide particles with high hiding power.

An efficient hybrid, nanostructured, epoxidation catalyst: titanium silsesquioxane-polystyrene copolymer supported on SBA-15.

PubMed

Zhang, Lei; Abbenhuis, Hendrikus C L; Gerritsen, Gijsbert; Bhriain, Nollaig Ní; Magusin, Pieter C M M; Mezari, Brahim; Han, Wei; van Santen, Rutger A; Yang, Qihua; Li, Can

2007-01-01

A novel interfacial hybrid epoxidation catalyst was designed with a new immobilization method for homogeneous catalysts by coating an inorganic support with an organic polymer film containing active sites. The titanium silsesquioxane (TiPOSS) complex, which contains a single-site titanium active center, was immobilized successfully by in-situ copolymerization on a mesoporous SBA-15-supported polystyrene polymer. The resulting hybrid materials exhibit attractive textural properties (highly ordered mesostructure, large specific surface area (>380 m2 g-1) and pore volume (>or==0.46 cm3 g-1)), and high activity in the epoxidation of alkenes. In the epoxidation of cyclooctene with tert-butyl hydrogen peroxide (TBHP), the hybrid catalysts have rate constants comparable with that of their homogeneous counterpart, and can be recycled at least seven times. They can also catalyze the epoxidation of cyclooctene with aqueous H2O2 as the oxidant. In two-phase reaction media, the catalysts show much higher activity than their homogeneous counterpart due to the hydrophobic environment around the active centers. They behave as interfacial catalysts due to their multifunctionality, that is, the hydrophobicity of polystyrene and the polyhedral oligomeric silsesquioxanes (POSS), and the hydrophilicity of the silica and the mesoporous structure. Combination of the immobilization of homogeneous catalysts on two conventional supports, inorganic solid and organic polymer, is demonstrated to achieve novel heterogeneous catalytic ensembles with the merits of attractive textural properties, tunable surface properties, and optimized environments around the active sites.

Cellular Interactions and Biological Responses to Titanium Dioxide Nanoparticles in HepG2 and BEAS-2B Cells: Role of Cell Culture Media

EPA Science Inventory

ABSTRACT We have shown previously that the composition of the biological medium used in vitro can affect the cellular interaction and biological response of titanium dioxide nanoparticles (nano-TiO2) in human lung epithelial cells. However, it is unclear if these effects are co...

Titanium Dioxide Photocatalytic Polymerization of Acrylamide for Gel Electrophoresis (TIPPAGE) of Proteins and Structural Identification by Mass Spectrometry

NASA Astrophysics Data System (ADS)

Zhang, Wenyang; Yuan, Zhiwei; Huang, Lulu; Kang, Jie; Jiang, Ruowei; Zhong, Hongying

2016-02-01

Polyacrylamide gel electrophoresis (PAGE) coupled with mass spectrometry has been well established for separating, identifying and quantifying protein mixtures from cell lines, tissues or other biological samples. The copolymerization process of acrylamide and bis-acrylamide is the key to mastering this powerful technique. In general, this is a vinyl addition reaction initiated by free radical-generating reagents such as ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) under basic pH and degassing experimental condition. We report herein a photocatalytic polymerization approach that is based on photo-generated hydroxyl radicals with nanoparticles of titanium dioxide. It was shown that the polymerization process is greatly accelerated in acidic condition when ultraviolet light shots on the gel solution containing TiO2 nanoparticles without degassing. This feature makes it very useful in preparing Triton X-100 acid urea (TAU) gel that has been developed for separating basic proteins such as histones and variants in acidic experimental condition. Additionally, the presence of titanium dioxide in the gel not only improves mechanistic property of gels but also changes the migration pattern of different proteins that have different affinities to titanium dioxide.

Antimicrobial activity of zinc and titanium dioxide nanoparticles against biofilm-producing methicillin-resistant Staphylococcus aureus

NASA Astrophysics Data System (ADS)

Jesline, A.; John, Neetu P.; Narayanan, P. M.; Vani, C.; Murugan, Sevanan

2015-02-01

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major nosocomial pathogens responsible for a wide spectrum of infections and the emergence of bacterial resistance to antibiotics has lead to treatment drawbacks towards large number of drugs. Formation of biofilms is the main contributing factor to antibiotic resistance. The development of reliable processes for the synthesis of zinc oxide nanoparticles is an important aspect of nanotechnology today. Zinc oxide and titanium dioxide nanoparticles comprise well-known inhibitory and bactericidal effects. Emergence of antimicrobial resistance by pathogenic bacteria is a major health problem in recent years. This study was designed to determine the efficacy of zinc and titanium dioxide nanoparticles against biofilm producing methicillin-resistant S. aureus. Biofilm production was detected by tissue culture plate method. Out of 30 MRSA isolates, 22 isolates showed strong biofilm production and 2 showed weak and moderate biofilm formation. Two strong and weak biofilm-producing methicillin-resistant S. aureus isolates were subjected to antimicrobial activity using commercially available zinc and titanium dioxide nanoparticles. Thus, the nanoparticles showed considerably good activity against the isolates, and it can be concluded that they may act as promising, antibacterial agents in the coming years.

Titanium Dioxide Photocatalytic Polymerization of Acrylamide for Gel Electrophoresis (TIPPAGE) of Proteins and Structural Identification by Mass Spectrometry.

PubMed

Zhang, Wenyang; Yuan, Zhiwei; Huang, Lulu; Kang, Jie; Jiang, Ruowei; Zhong, Hongying

2016-02-11

Polyacrylamide gel electrophoresis (PAGE) coupled with mass spectrometry has been well established for separating, identifying and quantifying protein mixtures from cell lines, tissues or other biological samples. The copolymerization process of acrylamide and bis-acrylamide is the key to mastering this powerful technique. In general, this is a vinyl addition reaction initiated by free radical-generating reagents such as ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) under basic pH and degassing experimental condition. We report herein a photocatalytic polymerization approach that is based on photo-generated hydroxyl radicals with nanoparticles of titanium dioxide. It was shown that the polymerization process is greatly accelerated in acidic condition when ultraviolet light shots on the gel solution containing TiO2 nanoparticles without degassing. This feature makes it very useful in preparing Triton X-100 acid urea (TAU) gel that has been developed for separating basic proteins such as histones and variants in acidic experimental condition. Additionally, the presence of titanium dioxide in the gel not only improves mechanistic property of gels but also changes the migration pattern of different proteins that have different affinities to titanium dioxide.

Titanium Dioxide Photocatalytic Polymerization of Acrylamide for Gel Electrophoresis (TIPPAGE) of Proteins and Structural Identification by Mass Spectrometry

PubMed Central

Zhang, Wenyang; Yuan, Zhiwei; Huang, Lulu; Kang, Jie; Jiang, Ruowei; Zhong, Hongying

2016-01-01

Polyacrylamide gel electrophoresis (PAGE) coupled with mass spectrometry has been well established for separating, identifying and quantifying protein mixtures from cell lines, tissues or other biological samples. The copolymerization process of acrylamide and bis-acrylamide is the key to mastering this powerful technique. In general, this is a vinyl addition reaction initiated by free radical-generating reagents such as ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) under basic pH and degassing experimental condition. We report herein a photocatalytic polymerization approach that is based on photo-generated hydroxyl radicals with nanoparticles of titanium dioxide. It was shown that the polymerization process is greatly accelerated in acidic condition when ultraviolet light shots on the gel solution containing TiO2 nanoparticles without degassing. This feature makes it very useful in preparing Triton X-100 acid urea (TAU) gel that has been developed for separating basic proteins such as histones and variants in acidic experimental condition. Additionally, the presence of titanium dioxide in the gel not only improves mechanistic property of gels but also changes the migration pattern of different proteins that have different affinities to titanium dioxide. PMID:26865351

Milestones in Functional Titanium Dioxide Thermal Spray Coatings: A Review

NASA Astrophysics Data System (ADS)

Gardon, M.; Guilemany, J. M.

2014-04-01

Titanium dioxide has been the most investigated metal oxide due to its outstanding performance in a wide range of applications, chemical stability and low cost. Coating processes that can produce surfaces based on this material have been deeply studied. Nevertheless, the necessity of coating large areas by means of rapid manufacturing processes renders laboratory-scale techniques unsuitable, leading to a noteworthy interest from the thermal spray (TS) community in the development of significant intellectual property and a large number of scientific publications. This review unravels the relationship between titanium dioxide and TS technologies with the aim of providing detailed information related to the most significant achievements, lack of knowhow, and performance of TS TiO2 functional coatings in photocatalytic, biomedical, and other applications. The influence of thermally activated techniques such as atmospheric plasma spray and high-velocity oxygen fuel spray on TiO2 feedstock based on powders and suspensions is revised; the influence of spraying parameters on the microstructural and compositional changes and the final active behavior of the coating have been analyzed. Recent findings on titanium dioxide coatings deposited by cold gas spray and the capacity of this technology to prevent loss of the nanostructured anatase metastable phase are also reviewed.

The role of carbon dioxide in chemoselective hydrogenation of halonitroaromatics over supported noble metal catalysts in supercritical carbon dioxide.

PubMed

Ichikawa, Shinichiro; Tada, Mizuki; Iwasawa, Yasuhiro; Ikariya, Takao

2005-02-21

Chemoselective hydrogenation of halogenated nitrobenzenes over Pt/C catalysts proceeds effectively in supercritical carbon dioxide (scCO2) to produce halogenated anilines with excellent selectivity; the rate of the hydrogenation of nitro groups is markedly enhanced in scCO2 compared to the neat reaction, and the dehalogenation reaction is significantly suppressed.

Catalyst for the reduction of sulfur dioxide to elemental sulfur

DOEpatents

Jin, Y.; Yu, Q.; Chang, S.G.

1996-02-27

The inventive catalysts allow for the reduction of sulfur dioxide to elemental sulfur in smokestack scrubber environments. The catalysts have a very high sulfur yield of over 90% and space velocity of 10,000 h{sup {minus}1}. They also have the capacity to convert waste gases generated during the initial conversion into elemental sulfur. The catalysts have inexpensive components, and are inexpensive to produce. The net impact of the invention is to make this technology practically available to industrial applications. 21 figs.

Catalyst for the reduction of sulfur dioxide to elemental sulfur

DOEpatents

Jin, Yun; Yu, Qiquan; Chang, Shih-Ger

1996-01-01

The inventive catalysts allow for the reduction of sulfur dioxide to elemental sulfur in smokestack scrubber environments. The catalysts have a very high sulfur yield of over 90% and space velocity of 10,000 h.sup.-1. They also have the capacity to convert waste gases generated during the initial conversion into elemental sulfur. The catalysts have inexpensive components, and are inexpensive to produce. The net impact of the invention is to make this technology practically available to industrial applications.

Titanium-containing Raney nickel catalyst for hydrogen electrodes in alkaline fuel cell systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mund, K.; Richter, G.; von Sturm, F.

In alkaline hydrogen-oxygen fuel cells Raney nickel is employed as catalyst for hydrogen electrodes. The rate of anodic hydrogen conversion has been increased significantly by using a titanium-containing Raney nickel. The properties of the catalyst powder, the influence of particle diameter, and the behavior of electrodes under load are described. Impedance measurements have been used to characterize the electrodes. In fuel cell systems the supported electrodes are normally operated at current densities up to 0.4 A . cm/sup -2/; the overload current density of 1 A . cm/sup -2/ can be maintained for several hours. (15 fig.)

Zeolite Y encapsulated with Fe-TiO2 for ultrasound-assisted degradation of amaranth dye in water.

PubMed

Alwash, Atheel Hassan; Abdullah, Ahmad Zuhairi; Ismail, Norli

2012-09-30

A new heterogeneous catalyst for sonocatalytic degradation of amaranth dye in water was synthesized by introducing titania into the pores of zeolite (NaY) through ion exchange method while Fe (III) was immobilized on the encapsulated titanium via impregnation method. XRD results could not detect any peaks for titanium oxide or Fe(2)O(3) due to its low loading. The UV-vis analysis proved a blue shift toward shorter wavelength after the loading of Ti into NaY while a red shift was detected after the loading of Fe into the encapsulated titanium. Different reaction variables such as TiO(2) content, amount of Fe, pH values, amount of hydrogen peroxide, catalyst loading and the initial dye concentration were studied to estimate their effect on the decolorization efficiency of amaranth. The maximum decolorization efficiency achieved was 97.5% at a solution pH of 2.5, catalyst dosage of 2 g/L, 20 mmol/100 mL of H(2)O(2) and initial dye concentration of 10 mg/L. The new heterogeneous catalyst Fe/Ti-NaY was a promising catalyst for this reaction and showed minimum Fe leaching at the end of the reaction. Copyright © 2012 Elsevier B.V. All rights reserved.

Coupling molecular catalysts with nanostructured surfaces for efficient solar fuel production

NASA Astrophysics Data System (ADS)

Jin, Tong

Solar fuel generation via carbon dioxide (CO2) reduction is a promising approach to meet the increasing global demand for energy and to minimize the impact of energy consumption on climate change. However, CO2 is thermodynamically stable; its activation often requires the use of appropriate catalysts. In particular, molecular catalysts with well-defined structures and tunability have shown excellent activity in photochemical CO2 reduction. These homogenous catalysts, however, suffer from poor stability under photochemical conditions and difficulty in recycling from the reaction media. Heterogenized molecular catalysts, particularly those prepared by coupling molecular catalysts with solid-state surfaces, have attracted more attention in recent years as potential solutions to address the issues associated with molecular catalysts. In this work, solar CO2 reduction is investigated using systems coupling molecular catalysts with robust nanostructured surfaces. In Chapter 2, heterogenization of macrocyclic cobalt(III) and nickel (II) complexes on mesoporous silica surface was achieved by different methods. Direct ligand derivatization significantly lowered the catalytic activity of Co(III) complex, while grafting the Co(III) complex onto silica surface through Si-O-Co linkage resulted in hybrid catalysts with excellent activity in CO2 reduction in the presence of p-terphenyl as a molecular photosensitizer. An interesting loading effect was observed, in which the optimal activity was achieved at a medium Co(III) surface density. Heterogenization of the Ni(II) complex on silica surface has also been implemented, the poor photocatalytic activity of the hybrid catalyst can be attributed to the intrinsic nature of the homogeneous analogue. This study highlighted the importance of appropriate linking strategies in preparing functional heterogenized molecular catalysts. Coupling molecular complexes with light-harvesting surfaces could avoid the use of expensive molecular photosensitizers. In Chapter 3, effective coupling of the macrocyclic Co(III) complex with titanium dioxide (TiO¬2) nanoparticles was achieved by two deposition methods. The synthesized hybrid photocatalysts were thoroughly characterized with a variety of techniques. Upon UV light irradiation, photoexcited electrons in TiO2 nanoparticles were transferred to the surface Co(III) catalyst for CO2 reduction. Production of carbon monoxide (CO) from CO2 was confirmed by isotope labeling combined with infrared spectroscopy. Deposition of the Co(III) catalyst through Ti-O-Co linkages was essential for the photo-induced electron transfer and CO2-reduction activity using the hybrid photocatalysts. In Chapter 4, molecular Re(I) and Co(II) catalysts were coupled with silicon-based photoelectrodes, including a silicon nanowire (SiNW) photoelectrode, to achieve photoelectrochemical CO2 reduction. Photovoltages between 300-600 mV were obtained using the molecular catalysts on the silicon photoelectrodes. SiNWs exhibited enhanced properties, including significantly higher photovoltages than a planar silicon photoelectrode, the ability to protect one of the molecular catalysts from photo-induced decomposition, and excellent selectivity towards CO production in CO2 reduction. Recent theoretical and experimental work have demonstrated low-energy, binuclear pathways for CO2-to-CO conversion using several molecular catalysts. In such binuclear pathways, two metal centers work cooperatively to achieve two-electron CO2 reduction. Chapter 5 describes our effort to promote the binuclear pathway by grafting the molecular Co(III) catalyst onto silica surfaces. Different linking strategies were attempted to achieve this goal by planting the surface Co(III) sites in close proximity.

Catalytic removal of sulfur dioxide from dibenzothiophene sulfone over Mg-Al mixed oxides supported on mesoporous silica.

PubMed

You, Nansuk; Kim, Min Ji; Jeong, Kwang-Eun; Jeong, Soon-Yong; Park, Young-Kwon; Jeon, Jong-Ki

2010-05-01

Dibenzothiophene sulfone (DBTS), one of the products of the oxidative desulfurization of heavy oil, can be removed through extraction as well as by an adsorption process. It is necessary to utilize DBTS in conjunction with catalytic cracking. An object of the present study is to provide an Mg-Al-mesoporous silica catalyst for the removal of sulfur dioxide from DBTS. The characteristics of the Mg-Al-mesoporous silica catalyst were investigated through N2 adsorption, XRD, ICP, and XRF. An Mg-Al-mesoporous silica catalyst formulated in a direct incorporation method showed higher catalytic performance compared to pure MgO during the catalytic removal of sulfur dioxide from DBTS. The higher dispersion of Mg as well as the large surface area of the Mg-Al-mesoporous silica catalyst strongly influenced the catalyst basicity in DBTS cracking.

Facile one-pot synthesis of nickel-incorporated titanium dioxide/graphene oxide composites: Enhancement of photodegradation under visible-irradiation

NASA Astrophysics Data System (ADS)

Pham, Thanh-Truc; Nguyen-Huy, Chinh; Shin, Eun Woo

2016-07-01

Nickel (Ni)-incorporated titanium dioxide (TiO2)/graphene oxide composite photocatalysts were prepared by anchoring the TiO2 and Ni onto the surface of graphene oxide (GO) sheets by a straightforward microwave-assisted, one-pot method for the first time. The as-prepared composite photocatalysts with high Ni content (40-50 wt%) showed good adsorption capacity in the dark and high reaction rate constants under visible illumination while the composite photocatalysts with low Ni content (5-10 wt%) exhibited weak activity. An anatase phase, a small amount of rutile phase and Ni metal were detected using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Raman measurements identified a small fraction of NiTiO3 only at high Ni content. The formation of NiTiO3 and the increase in the specific surface area (SSA) for 40 and 50 wt% Ni-loaded catalysts improved the adsorption capacity and photocatalytic activity upon exposure to visible light, resulting in very effective removal of dye contaminants under visible light irradiation. Increasing the Ni content up to 40 and 50 wt% induced not only a structural change affording high porosity but also a narrowing of the band gap to 2.51 eV. Meanwhile, the presence of GO in the composite photocatalysts inhibited the agglomeration of Ni particles even at high Ni content, resulting in similar Ni particle sizes regardless of the Ni content. At the same time, Ni metal accelerated the reduction of the GO sheets, as evidenced by the Raman data.

The structure of biocoats based on TiO2 doped with nitrogen study

NASA Astrophysics Data System (ADS)

Boytsova, E. L.; Leonova, L. A.; Pichugin, V. F.

2018-04-01

Nitrogen-doped titanium dioxide (N-TiO2) nanofilms were deposited by reactive magnetron sputtering under different bias voltage. The mode of sputtering influences to formation and properties of titanium films. X-ray diffraction (XRD) was used to study the phase transition and crystallinity of the nanofilms. A technique of layer-by-layer measurement of Raman scattering from nanostructured titanium dioxide films based on a preliminary sputtering of the films by argon beam under an angle of 45° and less has been developed. Experimentally confirmed low dissolution rate of the coating in NaCl saline (0.9%).

Antimicrobial polymers - The antibacterial effect of photoactivated nano titanium dioxide polymer composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huppmann, T., E-mail: teresa.huppmann@tum.de; Leonhardt, S., E-mail: stefan.leonhardt@mytum.de, E-mail: erhard.krampe@tum.de; Krampe, E., E-mail: stefan.leonhardt@mytum.de, E-mail: erhard.krampe@tum.de

To obtain a polymer with antimicrobial properties for medical and sanitary applications nanoscale titanium dioxide (TiO{sub 2}) particles have been incorporated into a medical grade polypropylene (PP) matrix with various filler contents (0 wt %, 2 wt %, 10 wt % and 15 wt %). The standard application of TiO{sub 2} for antimicrobial efficacy is to deposit a thin TiO{sub 2} coating on the surface. In contrast to the common way of applying a coating, TiO{sub 2} particles were applied into the bulk polymer. With this design we want to ensure antimicrobial properties even after application of impact effects thatmore » could lead to surface defects. The filler material (Aeroxide® TiO{sub 2} P25, Evonik) was applied via melt compounding and the compounding parameters were optimized with respect to nanoscale titanium dioxide. In a next step the effect of UV-irradiation on the compounds concerning their photocatalytic activity, which is related to the titanium dioxide amount, was investigated. The photocatalytic effect of TiO{sub 2}-PP-composites was analyzed by contact angle measurement, by methylene blue testing and by evaluation of inactivation potential for Escherichia coli (E.coli) bacteria. The dependence of antimicrobial activity on the filler content was evaluated, and on the basis of different titanium dioxide fractions adequate amounts of additives within the compounds were discussed. Specimens displayed a higher photocatalytic and also antimicrobial activity and lower contact angles with increasing titania content. The results suggest that the presence of titania embedded in the PP matrix leads to a surface change and a photocatalytic effect with bacteria killing result.« less

Catalyst cartridge for carbon dioxide reduction unit

NASA Technical Reports Server (NTRS)

Holmes, R. F. (Inventor)

1973-01-01

A catalyst cartridge, for use in a carbon dioxide reducing apparatus in a life support system for space vehicles, is described. The catalyst cartridge includes an inner perforated metal wall, an outer perforated wall space outwardly from the inner wall, a base plate closing one end of the cartridge, and a cover plate closing the other end of the cartridge. The cover plate has a central aperture through which a supply line with a heater feeds a gaseous reaction mixture comprising hydrogen and carbon dioxide at a temperature from about 1000 to about 1400 F. The outer surfaces of the internal wall and the inner surfaces of the outer wall are lined with a ceramic fiber batting material of sufficient thickness to prevent carbon formed in the reaction from passing through it. The portion of the surfaces of the base and cover plates defined within the inner and outer walls are also lined with ceramic batting. The heated reaction mixture passes outwardly through the inner perforated wall and ceramic batting and over the catalyst. The solid carbon product formes is retained within the enclosure containing the catalyst. The solid carbon product formed is retained within the enclosure containing the catalyst. The water vapor and unreacted carbon dioxide and any intermediate products pass through the perforations of the outer wall.

Photocatalytic destruction of chlorinated solvents with solar energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pacheco, J.; Prairie, M.; Yellowhorse, L.

1990-01-01

Sandia National Laboratories and the Solar Energy Research Institute are developing a photocatalytic process to destroy organic contaminants in water. Tests with common water pollutants are being conducted at Sandia's Solar Thermal Test Facility using a near commercial-scale single-axis tracking parabolic trough system with glass pipe mounted at its focus. Experiments at this scale provide verification of laboratory studies and allow examination of design and operation issues at a real-life scale. The catalyst, titanium dioxide (TiO{sub 2}), is a harmless material found in paint, cosmetics and toothpaste. Experiments were conducted to determine the effect of key process parameters on destructionmore » rates of two chlorinated organic compounds which are common water pollutants: trichloroethylene and trichloroethane. In this paper, we summarize the engineering-scale results of these experiments and analyses. 21 refs., 8 figs.« less

Fluidizable particulate materials and methods of making same

DOEpatents

Gupta, Raghubir P.

1999-01-01

The invention provides fluidizable, substantially spherical particulate material of improved attrition resistance having an average particle size from about 100 to about 400 microns useful as sorbents, catalysts, catalytic supports, specialty ceramics or the like. The particles are prepared by spray drying a slurry comprising inorganic starting materials and an organic binder. Exemplary inorganic starting materials include mixtures of zinc oxide with titanium dioxide, or with iron oxide, alumina or the like. Exemplary organic binders include polyvinyl alcohol, hydroxypropylemethyl cellulose, polyvinyl acetate and the like. The spray dried particles are heat treated at a first temperature wherein organic binder material is removed to thereby provide a porous structure to the particles, and thereafter the particles are calcined at a higher temperature to cause reaction of the inorganic starting materials and to thereby form the final inorganic particulate material.

TUNGSTEN BRONZE RELATED NON-NOBLE ELECTROCATALYSTS.

DTIC Science & Technology

FUEL CELLS, *CATALYSTS), (*OXYGEN, *ELECTRODES), (* SILICIDES , ELECTRODES), (*CARBIDES, ELECTRODES), (*TUNGSTEN COMPOUNDS, *ELECTROCHEMISTRY...CATALYSTS, TITANIUM COMPOUNDS, ZIRCONIUM COMPOUNDS, VANADIUM COMPOUNDS, NIOBIUM COMPOUNDS, TUNGSTEN COMPOUNDS, TANTALUM COMPOUNDS, MOLYBDENUM COMPOUNDS, SULFURIC ACID, CRYSTAL GROWTH, SODIUM COMPOUNDS

Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

DOEpatents

Koc, Rasit; Glatzmaier, Gregory C.

1995-01-01

A process for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

DOEpatents

Koc, R.; Glatzmaier, G.C.

1995-05-23

A process is disclosed for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

Comparative evaluation of the three different surface treatments - conventional, laser and Nano technology methods in enhancing the surface characteristics of commercially pure titanium discs and their effects on cell adhesion: An in vitro study.

PubMed

Vignesh; Nayar, Sanjna; Bhuminathan; Mahadevan; Santhosh, S

2015-04-01

The surface area of the titanium dental implant materials can be increased by surface treatments without altering their shape and form, thereby increasing the biologic properties of the biomaterial. A good biomaterial helps in early cell adhesion and cell signaling. In this study, the commercially pure titanium surfaces were prepared to enable machined surfaces to form a control material and to be compared with sandblasted and acid-etched surfaces, laser treated surfaces and titanium dioxide (20 nm) Nano-particle coated surfaces. The surface elements were characterized. The biocompatibility was evaluated by cell culture in vitro using L929 fibroblasts. The results suggested that the titanium dioxide Nano-particle coated surfaces had good osteoconductivity and can be used as a potential method for coating the biomaterial.

Photocatalytic oxidation mechanism of isobutane in contact with titanium dioxide (TiO2)

NASA Technical Reports Server (NTRS)

Formenti, M.; Juillet, F.; Teichner, S. J.

1977-01-01

The photocatalytic oxidation of isobutane to acetone in the presence of irradiated ultraviolet irradiated titanium dioxide was found to occur in several steps. Insertion of an oxygen atom onto the tertiary carbon transforming the isobutane into tertiary butanol occurred first. This step implied the photonic formation of the 02- species and its reaction with positive holes. The tertiary butanol was then dehydrated to isobutene which is oxidized acetone and carbon dioxide. Insertion of an oxygen atom onto the primary carbon led to isobutanal after oxidation to the alcohol. An analogous reaction scheme was proposed for all alkanes.

NANOSTRUCTURED METAL OXIDE CATALYSTS VIA BUILDING BLOCK SYNTHESES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Craig E. Barnes

2013-03-05

A broadly applicable methodology has been developed to prepare new single site catalysts on silica supports. This methodology requires of three critical components: a rigid building block that will be the main structural and compositional component of the support matrix; a family of linking reagents that will be used to insert active metals into the matrix as well as cross link building blocks into a three dimensional matrix; and a clean coupling reaction that will connect building blocks and linking agents together in a controlled fashion. The final piece of conceptual strategy at the center of this methodology involves dosingmore » the building block with known amounts of linking agents so that the targeted connectivity of a linking center to surrounding building blocks is obtained. Achieving targeted connectivities around catalytically active metals in these building block matrices is a critical element of the strategy by which single site catalysts are obtained. This methodology has been demonstrated with a model system involving only silicon and then with two metal-containing systems (titanium and vanadium). The effect that connectivity has on the reactivity of atomically dispersed titanium sites in silica building block matrices has been investigated in the selective oxidation of phenols to benezoquinones. 2-connected titanium sites are found to be five times as active (i.e. initial turnover frequencies) than 4-connected titanium sites (i.e. framework titanium sites).« less

Sealing glasses for titanium and titanium alloys

DOEpatents

Brow, R.K.; McCollister, H.L.; Phifer, C.C.; Day, D.E.

1997-07-15

Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B{sub 2}O{sub 3}), barium oxide (BaO), lanthanum oxide (La{sub 2}O{sub 3}), and at least one other oxide selected from the group consisting of aluminum oxide (Al{sub 2}O{sub 3}), calcium oxide (CaO), lithium oxide (Li{sub 2}O), sodium oxide (Na{sub 2}O), silicon dioxide (SiO{sub 2}), or titanium dioxide (TiO{sub 2}). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900 C, and generally about 700--800 C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps). 1 fig.

Sealing glasses for titanium and titanium alloys

DOEpatents

Brow, Richard K.; McCollister, Howard L.; Phifer, Carol C.; Day, Delbert E.

1997-01-01

Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B.sub.2 O.sub.3), barium oxide (BaO), lanthanum oxide (La.sub.2 O.sub.3), and at least one other oxide selected from the group consisting of aluminum oxide (Al.sub.2 O.sub.3), calcium oxide (CaO), lithium oxide (Li.sub.2 O), sodium oxide (Na.sub.2 O), silicon dioxide (SiO.sub.2), or titanium dioxide (TiO.sub.2). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900.degree. C., and generally about 700.degree.-800.degree. C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

Sealing glasses for titanium and titanium alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brow, R.K.; McCollister, H.L.; Phifer, C.C.

1997-07-15

Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B{sub 2}O{sub 3}), barium oxide (BaO), lanthanum oxide (La{sub 2}O{sub 3}), and at least one other oxide selected from the group consisting of aluminum oxide (Al{sub 2}O{sub 3}), calcium oxide (CaO), lithium oxide (Li{sub 2}O), sodium oxide (Na{sub 2}O), silicon dioxide (SiO{sub 2}), or titanium dioxide (TiO{sub 2}). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansionmore » about that of titanium or titanium alloys, and with sealing temperatures less than about 900 C, and generally about 700--800 C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps). 1 fig.« less

Influence of acid chain length on the properties of TiO2 prepared by sol-gel method and LC-MS studies of methylene blue photodegradation.

PubMed

Bakre, Pratibha V; Volvoikar, Prajesh S; Vernekar, Amit A; Tilve, S G

2016-07-15

Nano-sized titanium dioxide photocatalysts were synthesized by hybrid hydrolytic nonhydrolytic sol-gel method using aliphatic organic acid templates to study the effect of chain length on their properties. X-ray diffraction pattern indicated crystalline anatase phase. The Barrett-Joyner-Halenda surface area measurement gave surface area ranging from 98.4 to 205.5m(2)/g and was found to be dependent on the chain length of the aliphatic acid. The longer chain acids rendered the material with high surface area. The organic acids acted as bidentate ligand and a surfactant in controlling the size and the mesoporosity. The size of the TiO2 nanoparticulate was found to be in the range of 10-18nm. The catalyst prepared by employing long chain acids octanoic acid and palmitic acid had smaller size, narrow pore radius, higher surface area and showed better photocatalytic activity than the commercially available Degussa P25 catalyst for the degradation of methylene blue dye. A new intermediate was identified by tandem liquid chromatography mass spectrometry studies during the degradation of methylene blue solution. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthesis and characterization of TiO2 loaded cashew nut shell activated carbon and photocatalytic activity on BG and MB dyes under sunlight radiation.

PubMed

Ragupathy, S; Raghu, K; Prabu, P

2015-03-05

Synthesis of titanium dioxide (TiO2) nanoparticles and TiO2 loaded cashew nut shell activated carbon (TiO2/CNSAC) had been undertaken using sol-gel method and their application in BG and MB dyes removal under sunlight radiation has been investigated. The synthesized photocatalysts were characterized by X-ray diffraction analysis (XRD), Fourier infra-red spectroscopy (FT-IR), UV-Vis-diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX). The various experimental parameters like amount of catalyst, contact time for efficient dyes degradation of BG and MB were concerned in this study. Activity measurements performed under solar irradiation has shown good results for the photodegradation of BG and MB in aqueous solution. It was concluded that the higher photocatalytic activity in TiO2/CNSAC was due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst. The kinetic data were also described by the pseudo-first-order and pseudo-second-order kinetic models. Copyright © 2014 Elsevier B.V. All rights reserved.

Heterogeneous activation of H2O2 by defect-engineered TiO(2-x) single crystals for refractory pollutants degradation: A Fenton-like mechanism.

PubMed

Zhang, Ai-Yong; Lin, Tan; He, Yuan-Yi; Mou, Yu-Xuan

2016-07-05

The heterogeneous catalyst plays a key role in Fenton-like reaction for advanced oxidation of refractory pollutants in water treatment. Titanium dioxide (TiO2) is a typical semiconductor with high industrial importance due to its earth abundance, low cost and no toxicity. In this work, it is found that TiO2 can heterogeneously activate hydrogen peroxide (H2O2, E°=1.78 eV), a common chemical oxidant, to efficiently generate highly-powerful hydroxyl radical, OH (E(0)=2.80 eV), for advanced water treatment, when its crystal shape, exposed facet and oxygen-stoichiometry are finely tuned. The defect-engineered TiO2 single crystals exposed by high-energy {001} facets exhibited an excellent Fenton-like activity and stability for degrading typical refractory organic pollutants such as methyl orange and p-nitrophenol. Its defect-centered Fenton-like superiority is mainly attributed to the crystal oxygen-vacancy, single-crystalline structure and exposed polar {001} facet. Our findings could provide new chance to utilize TiO2 for Fenton-like technology, and develop novel heterogeneous catalyst for advanced water treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

Low-pressure hydrogenation of carbon dioxide catalyzed by an iron pincer complex exhibiting noble metal activity.

PubMed

Langer, Robert; Diskin-Posner, Yael; Leitus, Gregory; Shimon, Linda J W; Ben-David, Yehoshoa; Milstein, David

2011-10-10

A highly active iron catalyst for the hydrogenation of carbon dioxide and bicarbonates works under remarkably low pressures and achieves activities similar to some of the best noble metal catalysts. A mechanism is proposed involving the direct attack of an iron trans-dihydride on carbon dioxide, followed by ligand exchange and dihydrogen coordination. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Correction: A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

PubMed

Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

2016-12-22

Correction for 'A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide' by Chee Koon Ng et al., Chem. Commun., 2016, 52, 11842-11845.

Iron on mixed zirconia-titania substrate Fischer-Tropsch catalyst and method of making same

DOEpatents

Dyer, Paul N.; Nordquist, Andrew F.; Pierantozzi, Ronald

1986-01-01

A Fischer-Tropsch catalyst comprising iron co-deposited with or deposited on particles comprising a mixture of zirconia and titania, preferably formed by co-precipitation of compounds convertible to zirconia and titania, such as zirconium and titanium alkoxide. The invention also comprises the method of making this catalyst and an improved Fischer-Tropsch reaction process in which the catalyst is utilized.

F-T process using an iron on mixed zirconia-titania supported catalyst

DOEpatents

Dyer, Paul N.; Nordquist, Andrew F.; Pierantozzi, Ronald

1987-01-01

A Fischer-Tropsch catalyst comprising iron co-deposited with or deposited on particles comprising a mixture of zirconia and titania, preferably formed by co-precipitation of compounds convertible to zirconia and titania, such as zirconium and titanium alkoxide. The invention also comprises the method of making this catalyst and an improved Fischer-Tropsch reaction process in which the catalyst is utilized.

Application of gas-fluid atomization technology in ultrosonic vibration cutting titanium alloy workpiece

NASA Astrophysics Data System (ADS)

Zhou, Zhimin; Zhang, Yuangliang; Li, Xiaoyan; Sun, Baoyuan

2009-11-01

To further improve machined surface quality of diamond cutting titanium workpiece and reduce diamond tool wear, it puts forward a kind of machining technology with mixture of carbon dioxide gas, water and vegetable oil atomized mist as cooling media in the paper. The cooling media is sprayed to cutting area through gas-liquid atomizer device to achieve purpose of cooling, lubricating, and protecting diamond tool. Experiments indicate that carbon dioxide gas can touch cutting surface more adequately through using gas-liquid atomization technology, which makes iron atoms of cutting surface cause a chemical reaction directly with carbon in carbon dioxide gas and reduce graphitizing degree of diamond tool. Thus, this technology of using gas-liquid atomization and ultrasonic vibration together for cutting Titanium Alloy is able to improve machined surface quality of workpiece and slow of diamond tool wear.

Adsorption of octylamine on titanium dioxide

NASA Astrophysics Data System (ADS)

Siwińska, Daria; Kołodziejczak-Radzimska, Agnieszka; Krysztafkiewicz, Andrzej; Jesionowski, Teofil

2009-05-01

Processes of adsorption and desorption of a model active substance (octylamine) on the surface of unmodified titanium dioxide (E 171) have been performed. The effects of concentration of octylamine and time of the process on the character of adsorption have been studied and the efficiency of the adsorption/desorption has been determined. The samples obtained have been studied by X-ray diffraction. The nitrogen adsorption/desorption isotherms, particle size distribution and absorption capacities of water, dibutyl phthalate and paraffin oil have been determined. The efficiency of octylamine adsorption on the surface of the titanium dioxide has been found positively correlated with the concentration of octylamine in the initial solution. The desorption of octylamine has decreased with increasing concentration of this compound adsorbed. For octylamine in low concentrations the physical adsorption has been found to dominate, which is desirable when using TiO 2 in the production of pharmaceuticals.

Thermochemical cyclic system for decomposing H/sub 2/O and/or CO/sub 2/ by means of cerium-titanium-sodium-oxygen compounds

DOEpatents

Bamberger, C.E.

1980-04-24

A thermochemical closed cyclic process for the decomposition of water and/or carbon dioxide to hydrogen and/or carbon monoxide begins with the reaction of ceric oxide (CeO/sub 2/), titanium dioxide (TiO/sub 2/) and sodium titanate (Na/sub 2/TiO/sub 3/) to form sodium cerous titanate (NaCeTi/sub 2/O/sub 6/) and oxygen. Sodium cerous titanate (NaCeTi/sub 2/O/sub 6/) reacted with sodium carbonate (Na/sub 2/CO/sub 3/) in the presence of steam, produces hydrogen. The same reaction, in the absence of steam, produces carbon monoxide. The products, ceric oxide and sodium titanate, obtained in either case, are treated with carbon dioxide and water to produce ceric oxide, titanium dioxide, sodium titanate, and sodium bicarbonate. After dissolving sodium bicarbonate from the mixture in water, the remaining insoluble compounds are used as starting materials for a subsequent cycle. The sodium bicarbonate can be converted to sodium carbonate by heating and returned to the cycle.

The antibacterial effects of silver, titanium dioxide and silica dioxide nanoparticles compared to the dental disinfectant chlorhexidine on Streptococcus mutans using a suite of bioassays

PubMed Central

Besinis, Alexandros; De Peralta, Tracy

2014-01-01

Metal-containing nanomaterials have the potential to be used in dentistry for infection control, but little is known about their antibacterial properties. This study investigated the toxicity of silver (Ag), titanium dioxide and silica nanoparticles (NPs) against the oral pathogenic species of Streptococcus mutans, compared to the routine disinfectant, chlorhexidine. The bacteria were assessed using the minimum inhibitory concentration assay for growth, fluorescent staining for live/dead cells, and measurements of lactate. All the assays showed that Ag NPs had the strongest antibacterial activity of the NPs tested, with bacterial growth also being 25-fold lower than that in chlorhexidine. The survival rate of bacteria under the effect of 100 mg l−1 Ag NPs in the media was 2% compared to 60% with chlorhexidine, while the lactate concentration was 0.6 and 4.0 mM, respectively. Silica and titanium dioxide NPs had limited effects. Dialysis experiments showed negligible silver dissolution. Overall, Ag NPs were the best disinfectant and performed better than chlorhexidine. Improvements to the MIC assay are suggested. PMID:23092443

Thermochemical cyclic system for decomposing H.sub.2 O and/or CO.sub.2 by means of cerium-titanium-sodium-oxygen compounds

DOEpatents

Bamberger, Carlos E.

1982-01-01

A thermochemical closed cyclic process for the decomposition of water and/or carbon dioxide to hydrogen and/or carbon monoxide begins with the reaction of ceric oxide (CeO.sub.2), titanium dioxide (TiO.sub.2) and sodium titanate (Na.sub.2 TiO.sub.3) to form sodium cerous titanate (NaCeTi.sub.2 O.sub.6) and oxygen. Sodium cerous titanate (NaCeTi.sub.2 O.sub.6) reacted with sodium carbonate (Na.sub.2 CO.sub.3) in the presence of steam, produces hydrogen. The same reaction, in the absence of steam, produces carbon monoxide. The products, ceric oxide and sodium titanate, obtained in either case, are treated with carbon dioxide and water to produce ceric oxide, titanium dioxide, sodium titanate, and sodium bicarbonate. After dissolving sodium bicarbonate from the mixture in water, the remaining insoluble compounds are used as starting materials for a subsequent cycle. The sodium bicarbonate can be converted to sodium carbonate by heating and returned to the cycle.

Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

PubMed

Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

2016-02-05

As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gentamicin-Eluting Titanium Dioxide Nanotubes Grown on the Ultrafine-Grained Titanium.

PubMed

Nemati, Sima Hashemi; Hadjizadeh, Afra

2017-08-01

Titanium (Ti)-based materials is the most appropriate choices for the applications as orthopedic and dental implants. In this regard, ultrafine-grained (UFG) titanium with an enhanced mechanical properties and surface energy has attracted more attention. Titanium dioxide (TiO 2 ) nanotubes grown on the titanium could enhance bone bonding, cellular response and are good reservoirs for loading drugs and antibacterial agents. This article investigates gentamicin loading into and release from the TiO 2 nanotubes, grown on the UFG compared to coarse-grained (CG) titanium substrate surfaces. Equal Channel Angular Pressing (ECAP) was employed to produce the UFG structure titanium. TiO 2 nanotubes were grown by the anodizing technique on both UFG and CG titanium substrate surfaces. Scanning electron microscopy (SEM) imaging confirmed TiO 2 nanotube growth on the surface. The UV-vis spectroscopy analysis results show that the amount of gentamicin load-release in the anodized UFG titanium sample is higher than that of CG one which can be explained in terms of thicker TiO 2 nanotube arrays layer formed on UFG sample. Moreover, the anodized UFG titanium samples released the drug in a longer time than CG (1 day for the UFG titanium vs. 3 h for the CG one). Regarding wettability analysis, anodized UFG titanium sample showed more enhanced hydrophilicity than CG counterpart. Therefore, the significantly smaller grain size of pure titanium provided by the ECAP technique coupled with appropriate subsequent anodization treatment not only offers a good combination of biocompatibility and adequate mechanical properties but also it provides a delayed release condition for gentamicin.

Titanium dioxide, single-walled carbon nanotube composites

DOEpatents

Yao, Yuan; Li, Gonghu; Gray, Kimberly; Lueptow, Richard M.

2015-07-14

The present invention provides titanium dioxide/single-walled carbon nanotube composites (TiO.sub.2/SWCNTs), articles of manufacture, and methods of making and using such composites. In certain embodiments, the present invention provides membrane filters and ceramic articles that are coated with TiO.sub.2/SWCNT composite material. In other embodiments, the present invention provides methods of using TiO.sub.2/SWCNT composite material to purify a sample, such as a water or air sample.

The adsorption properties of titanium dioxide

NASA Astrophysics Data System (ADS)

Lanin, S. N.; Vlasenko, E. V.; Kovaleva, N. V.; Zung, Fam Tien

2008-12-01

The adsorption properties of titanium dioxide were studied by gas chromatography. We used organic compounds from different classes, namely, n-alkanes, n-alkenes (C6-C8), and polar compounds (electron donors and acceptors) as test adsorbates. The differential heats of adsorption and the contributions of dispersion and specific intermolecular interaction energies were determined for the systems from the experimental retention data. The electron-donor and electron-acceptor characteristics of the ultimately hydroxylated surface of TiO2 were evaluated.

Two Iron Complexes as Homogeneous and Heterogeneous Catalysts for the Chemical Fixation of Carbon Dioxide.

PubMed

Karan, Chandan Kumar; Bhattacharjee, Manish

2018-04-16

Two new bimetallic iron-alkali metal complexes of amino acid (serine)-based reduced Schiff base ligand were synthesized and structurally characterized. Their efficacy as catalysts for the chemical fixation of carbon dioxide was explored. The heterogeneous version of the catalytic reaction was developed by the immobilization of these homogeneous bimetallic iron-alkali metal complexes in an anion-exchange resin. The resin-bound complexes can be used as recyclable catalysts up to six cycles.

Advanced Catalysis Technologies: Lanthanum Cerium Manganese Hexaaluminate Combustion Catalysts for Flat Plate Reactor for Compact Steam Reformers

DTIC Science & Technology

2008-12-01

to decompose the urea into carbon dioxide and ammonia. This increased the pH and caused sol condensation. The mixture was calcined in air at 550°C...propane to carbon dioxide and water. Its high manganese content provides a higher intrinsic activity than the other catalysts and thus the lowest...lean natural gas turbines in order to reduce NOx emissions to reforming catalyst to convert diesel and kerosene to hydrogen rich gases. Unlike

Well-defined iron catalyst for improved hydrogenation of carbon dioxide and bicarbonate.

PubMed

Ziebart, Carolin; Federsel, Christopher; Anbarasan, Pazhamalai; Jackstell, Ralf; Baumann, Wolfgang; Spannenberg, Anke; Beller, Matthias

2012-12-26

The most efficient, stable, and easy-to-synthesize non-noble metal catalyst system for the reduction of CO(2) and bicarbonates is presented. In the presence of the iron(II)-fluoro-tris(2-(diphenylphosphino)phenyl)phosphino]tetrafluoroborate complex 3, the hydrogenation of bicarbonates proceeds in good yields with high catalyst productivity and activity (TON > 7500, TOF > 750). High-pressure NMR studies of the hydrogenation of carbon dioxide demonstrate that the corresponding iron-hydridodihydrogen complex 4 is crucial in the catalytic cycle.

Molecular dynamics simulations of the adsorption of bone morphogenetic protein-2 on surfaces with medical relevance.

PubMed

Utesch, Tillmann; Daminelli, Grazia; Mroginski, Maria Andrea

2011-11-01

Bone morphogenetic protein-2 (BMP-2) plays a crucial role in osteoblast differentiation and proliferation. Its effective therapeutic use for ectopic bone and cartilage regeneration depends, among other factors, on the interaction with the carrier at the implant site. In this study, we used classical molecular dynamics (MD) and a hybrid approach of steered molecular dynamics (SMD) combined with MD simulations to investigate the initial stages of the adsorption of BMP-2 when approaching two implant surfaces, hydrophobic graphite and hydrophilic titanium dioxide rutile. Surface adsorption was evaluated for six different orientations of the protein, two end-on and four side-on, in explicit water environment. On graphite, we observed a weak but stable adsorption. Depending on the initial orientation, hydrophobic patches as well as flexible loops of the protein were involved in the interaction with graphite. On the contrary, BMP-2 adsorbed only loosely to hydrophilic titanium dioxide. Despite a favorable interaction energy between protein and the TiO(2) surface, the rapid formation of a two-layer water structure prevented the direct interaction between protein and titanium dioxide. The first water adlayer had a strong repulsive effect on the protein, while the second attracted the protein toward the surface. For both surfaces, hydrophobic graphite and hydrophilic titanium dioxide, denaturation of BMP-2 induced by adsorption was not observed on the nanosecond time scale.

Biocompatibility and antibacterial activity of nitrogen-doped titanium dioxide nanoparticles for use in dental resin formulations

PubMed Central

Zane, Andrew; Zuo, Ranfang; Villamena, Frederick A; Rockenbauer, Antal; Digeorge Foushee, Ann Marie; Flores, Kristin; Dutta, Prabir K; Nagy, Amber

2016-01-01

The addition of antibacterial functionality to dental resins presents an opportunity to extend their useful lifetime by reducing secondary caries caused by bacterial recolonization. In this study, the potential efficacy of nitrogen-doped titanium dioxide nanoparticles for this purpose was determined. Nitrogen doping was carried out to extend the ultraviolet absorbance into longer wavelength blue light for increased biocompatibility. Titanium dioxide nanoparticles (approximately 20–30 nm) were synthesized with and without nitrogen doping using a sol–gel method. Ultraviolet–Visible spectroscopy indicated a band of trap states, with increasing blue light absorbance as the concentration of the nitrogen dopant increased. Electron paramagnetic resonance measurements indicated the formation of superoxide and hydroxyl radicals upon particle exposure to visible light and oxygen. The particles were significantly toxic to Escherichia coli in a dose-dependent manner after a 1-hour exposure to a blue light source (480 nm). Intracellular reactive oxygen species assay demonstrated that the particles caused a stress response in human gingival epithelial cells when exposed to 1 hour of blue light, though this did not result in detectable release of cytokines. No decrease in cell viability was observed by water-soluble tetrazolium dye assay. The results show that nitrogen-doped titanium dioxide nanoparticles have antibacterial activity when exposed to blue light, and are biocompatible at these concentrations. PMID:27980404

Biocompatibility and antibacterial activity of nitrogen-doped titanium dioxide nanoparticles for use in dental resin formulations.

PubMed

Zane, Andrew; Zuo, Ranfang; Villamena, Frederick A; Rockenbauer, Antal; Digeorge Foushee, Ann Marie; Flores, Kristin; Dutta, Prabir K; Nagy, Amber

The addition of antibacterial functionality to dental resins presents an opportunity to extend their useful lifetime by reducing secondary caries caused by bacterial recolonization. In this study, the potential efficacy of nitrogen-doped titanium dioxide nanoparticles for this purpose was determined. Nitrogen doping was carried out to extend the ultraviolet absorbance into longer wavelength blue light for increased biocompatibility. Titanium dioxide nanoparticles (approximately 20-30 nm) were synthesized with and without nitrogen doping using a sol-gel method. Ultraviolet-Visible spectroscopy indicated a band of trap states, with increasing blue light absorbance as the concentration of the nitrogen dopant increased. Electron paramagnetic resonance measurements indicated the formation of superoxide and hydroxyl radicals upon particle exposure to visible light and oxygen. The particles were significantly toxic to Escherichia coli in a dose-dependent manner after a 1-hour exposure to a blue light source (480 nm). Intracellular reactive oxygen species assay demonstrated that the particles caused a stress response in human gingival epithelial cells when exposed to 1 hour of blue light, though this did not result in detectable release of cytokines. No decrease in cell viability was observed by water-soluble tetrazolium dye assay. The results show that nitrogen-doped titanium dioxide nanoparticles have antibacterial activity when exposed to blue light, and are biocompatible at these concentrations.

Antibacterial activity and biofilm inhibition by surface modified titanium alloy medical implants following application of silver, titanium dioxide and hydroxyapatite nanocoatings.

PubMed

Besinis, A; Hadi, S D; Le, H R; Tredwin, C; Handy, R D

2017-04-01

One of the most common causes of implant failure is peri-implantitis, which is caused by bacterial biofilm formation on the surfaces of dental implants. Modification of the surface nanotopography has been suggested to affect bacterial adherence to implants. Silver nanoparticles are also known for their antibacterial properties. In this study, titanium alloy implants were surface modified following silver plating, anodisation and sintering techniques to create a combination of silver, titanium dioxide and hydroxyapatite (HA) nanocoatings. Their antibacterial performance was quantitatively assessed by measuring the growth of Streptococcus sanguinis, proportion of live/dead cells and lactate production by the microbes over 24 h. Application of a dual layered silver-HA nanocoating to the surface of implants successfully inhibited bacterial growth in the surrounding media (100% mortality), whereas the formation of bacterial biofilm on the implant surfaces was reduced by 97.5%. Uncoated controls and titanium dioxide nanocoatings showed no antibacterial effect. Both silver and HA nanocoatings were found to be very stable in biological fluids with material loss, as a result of dissolution, to be less than 0.07% for the silver nanocoatings after 24 h in a modified Krebs-Ringer bicarbonate buffer. No dissolution was detected for the HA nanocoatings. Thus, application of a dual layered silver-HA nanocoating to titanium alloy implants creates a surface with antibiofilm properties without compromising the HA biocompatibility required for successful osseointegration and accelerated bone healing.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mistry, Hemma; Varela, Ana Sofia; Bonifacio, Cecile S.

There is an urgent need to develop technologies that use renewable energy to convert waste products such as carbon dioxide into hydrocarbon fuels. Carbon dioxide can be electrochemically reduced to hydrocarbons over copper catalysts, although higher efficiency is required. We have developed oxidized copper catalysts displaying lower overpotentials for carbon dioxide electroreduction and record selectivity towards ethylene (60%) through facile and tunable plasma treatments. Herein we provide insight into the improved performance of these catalysts by combining electrochemical measurements with microscopic and spectroscopic characterization techniques. Operando X-ray absorption spectroscopy and cross-sectional scanning transmission electron microscopy show that copper oxides aremore » surprisingly resistant to reduction and copper + species remain on the surface during the reaction. Furthermore, our results demonstrate that the roughness of oxide-derived copper catalysts plays only a partial role in determining the catalytic performance, while the presence of copper + is key for lowering the onset potential and enhancing ethylene selectivity.« less

Carbon dioxide hydrogenation catalysed by well-defined Mn(i) PNP pincer hydride complexes.

PubMed

Bertini, Federica; Glatz, Mathias; Gorgas, Nikolaus; Stöger, Berthold; Peruzzini, Maurizio; Veiros, Luis F; Kirchner, Karl; Gonsalvi, Luca

2017-07-01

The catalytic reduction of carbon dioxide is of great interest for its potential as a hydrogen storage method and to use carbon dioxide as C-1 feedstock. In an effort to replace expensive noble metal-based catalysts with efficient and cheap earth-abundant counterparts, we report the first example of Mn(i)-catalysed hydrogenation of CO 2 to HCOOH. The hydride Mn(i) catalyst [Mn(PNP NH - i Pr)(H)(CO) 2 ] showed higher stability and activity than its Fe(ii) analogue. TONs up to 10 000 and quantitative yields were obtained after 24 h using DBU as the base at 80 °C and 80 bar total pressure. At catalyst loadings as low as 0.002 mol%, TONs greater than 30 000 could be achieved in the presence of LiOTf as the co-catalyst, which are among the highest activities reported for base-metal catalysed CO 2 hydrogenations to date.

Application of aluminum-supported Pd, Rh, and Rh-Pd nanoparticles in supercritical carbon dioxide system for hydrodebromination of polybrominated diphenyl ethers.

PubMed

Wu, Ben-Zen; Sun, Yu-Jie; Chen, Yan-Hua; Yak, Hwa Kwang; Yu, Jya-Jyun; Liao, Weisheng; Chiu, KongHwa; Peng, Shie-Ming

2016-08-01

Al-powder-supported Pd, Rh, and Rh-Pd catalysts were synthesized through a spontaneous redox reaction in aqueous solutions. These catalysts hydrodebrominated 4- and 4,4'-bromodiphenyl ethers in supercritical carbon dioxide at 200 atm CO2 containing 10 atm H2 and 80 °C in 1 h. Diphenyl ether was the major product of Pd/Al. Rh/Al and Rh-Pd/Al further hydrogenated two benzene rings of diphenyl ether to form dicyclohexyl ether. The hydrogenolysis of CO bonds on diphenyl ether over Rh/Al and Rh-Pd/Al was observed to generate cyclohexanol and cyclohexane (<1%). With respect to hydrodebromination efficiency and catalyst stability, Rh-Pd/Al among three catalysts is suggested to be used for ex situ degradation of polybrominated diphenyl ethers in supercritical carbon dioxide. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Improvement of the Resistance to Candida albicans and Trichophyton interdigitale of Some Woven Fabrics Based on Cotton.

PubMed

Surdu, Lilioara; Stelescu, Maria Daniela; Manaila, Elena; Nicula, Gheorghe; Iordache, Ovidiu; Dinca, Laurentiu Christian; Berechet, Mariana-Daniela; Vamesu, Mariana; Gurau, Dana

2014-01-01

This paper presents the improvement of the antimicrobial character of woven fabrics based on cotton. The woven fabrics were cleaned in oxygen plasma and treated by padding with silver chloride and titanium dioxide particles. The existence of silver and titanium on woven fabrics was evidenced by electronic microscope images (SEM, EDAX) and by flame atomic absorption spectrophotometry. The antimicrobial tests were performed with two fungi: Candida albicans and Trichophyton interdigitale. The obtained antimicrobial effect was considerably higher compared to the raw fabrics. Treatment of dyed fabrics with a colloidal solution based on silver chloride and titanium dioxide particles does not considerably influence colour resistance of dyes.

The Improvement of the Resistance to Candida albicans and Trichophyton interdigitale of Some Woven Fabrics Based on Cotton

PubMed Central

Stelescu, Maria Daniela; Manaila, Elena; Nicula, Gheorghe; Iordache, Ovidiu; Dinca, Laurentiu Christian; Berechet, Mariana-Daniela; Vamesu, Mariana; Gurau, Dana

2014-01-01

This paper presents the improvement of the antimicrobial character of woven fabrics based on cotton. The woven fabrics were cleaned in oxygen plasma and treated by padding with silver chloride and titanium dioxide particles. The existence of silver and titanium on woven fabrics was evidenced by electronic microscope images (SEM, EDAX) and by flame atomic absorption spectrophotometry. The antimicrobial tests were performed with two fungi: Candida albicans and Trichophyton interdigitale. The obtained antimicrobial effect was considerably higher compared to the raw fabrics. Treatment of dyed fabrics with a colloidal solution based on silver chloride and titanium dioxide particles does not considerably influence colour resistance of dyes. PMID:25276112

Research of obtaining TiO2 by sol-gel method using titanium isopropoxide TIP and tetra-n-butyl orthotitanate TNB

NASA Astrophysics Data System (ADS)

Gómez de Salazar, J. M.; Nutescu Duduman, C.; Juárez Gonzalez, M.; Palamarciuc, I.; Barrena Pérez, M. I.; Carcea, I.

2016-08-01

Titanium dioxide crystallises in three polymorphs: anatase, rutile and brookite. Rutile is most stable form of the TiO2 polymorphs. In this paper we concentrate on obtaining rutile and anatase, both used in various applications. The chosen method is sol-gel, which is a reliable method used for obtaining titanium oxides. We prepared titanium dioxide with using titanium isopropoxide (TIP) with chemical construction (C12H28O4Ti) and tetra-n-butyl orthotitanate (TNB) with chemical construction (C16H36O4Ti). The experiments were carried out in order to compare the results of the samples with similar reaction conditions, but with different precursors, thus concluding which precursor gives best results. Using different analysis techniques as X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Thermogravimetric Analysis (TGA) we characterised the samples morphologically and structurally.

Active Materials for Photonic Systems (AMPS)

DTIC Science & Technology

1998-04-13

titanium isopropoxide were used as metalorganic precursors. The PZT films grown on the (101) oriented Ru02 electrode layers are highly (001) oriented...fabrication it was noted mat adhesion loss occurred at the platinum/ titanium interface. This loss occurred during stripping of the photoresist layer used to...reveal that the titanium was present as titanium dioxide rather than as the original metal. This indicated that oxygen had diffused through the platinum

Electrocatalytic reduction of carbon dioxide on electrodeposited tin-based surfaces

NASA Astrophysics Data System (ADS)

Alba, Bianca Christina S.; Camayang, John Carl A.; Mopon, Marlon L.; del Rosario, Julie Anne D.

2017-08-01

The electrocatalytic reduction of carbon dioxide to small organic molecular compounds provides a means of generating alternative fuel source while suppressing climate change. Suitable catalysts, however, are necessary to optimize its reaction kinetics towards more valuable products. Consequently, in this study, electrodeposited Sn electrodes have been developed as catalysts for CO2 electroreduction. Deposition potential was varied to produce different Sn catalysts. SEM showed varying morphologies and increasing amount as the applied potential becomes more negative. Cyclic voltammetry and chronoamperometry showed that the activity and stability of the catalysts towards CO2 reduction depend on the morphology and presence of tin oxides. These results provide a better understanding on the performance of electrodeposited Sn-based surfaces as catalysts for CO2 reduction.

Catalysts for low-energy aldehyde processes

NASA Technical Reports Server (NTRS)

Gupta, A.; Rembaum, A.; Frazier, C.; Gray, H. B.

1977-01-01

Photochemical reaction of dicobalt octacarbonyl with polymeric support systems results in formation of polymer bonded metal catalyst. Catalyst is used in hydroformylation (addition of carbon dioxide and hydrogen) of olefins to yield aldehydes.

Carbon Dioxide Methanation for Human Exploration of Mars: A Look at Catalyst Longevity and Activity Using Supported Ruthenium

NASA Technical Reports Server (NTRS)

Petersen, Elspeth M.; Meier, Anne J.; Tessonnier, Jean-Philippe

2018-01-01

Overarching Purpose: To design a carbon dioxide methanation/Sabatier reaction catalyst able to withstand variable conditions including fluctuations in bed temperature and feed flow rates for 480 days of remote operation to produce seven tons of methane. Current Study Purpose: Examine supported Ruthenium as a carbon dioxide methanation catalyst to determine the effects support properties have on the active phase by studying activity and selectivity. Objective: The remote operation of the Mars ISRU (In Situ Resources Utilization) lander to produce rocket fuel prior to crew arrival on the planet to power an ascent vehicle. Constraints: Long-term operation (480 days); Variable conditions: Feed gas flow rates, Feed gas flow ratios, Reactor bed temperature.

Quantification of iprodione in dry basil using silica gel supported titanium dioxide.

PubMed

Maeda, Osamu; Oikawa, Chie; Noguchi, Kentaro; Shiomi, Nobuo; Toriba, Akira; Hayakawa, Kazuichi

2010-02-10

Iprodione is an agricultural fungicide that is difficult to detect in foods by HPLC because it coelutes with natural compounds in the food. We previously showed that food matrix could be degraded with titanium dioxide powder (TP). Here we describe an improved method for detection of iprodione using silica gel supported titanium dioxide (SGT). To synthesize SGT, titania-sol was mixed with diethanolamine, 2-propanol, and titanium tetraisopropoxide. After titania-sol was infiltrated into the silica gel (particle diameter 4 mm), the mixture was dried and then heated. Crude basil extract containing iprodione was mixed with SGT in a quartz vial, and the vial was irradiated with a UV light to selectively decompose the matrix interfering with the iprodione determination. In HPLC chromatograms of the treated solution, the interference peak decreased 35 times faster with SGT than with TP. When SGT (11 g) was added to the extract (20 mL) of dry basil (2 g), black light irradiation for 30 min was enough to quantify iprodione. The recovery rate of iprodione was 99.1%. Thus, the photocatalytic cleanup method using SGT is effective for analyzing residual iprodione in dry basil.

Evolution of Zinc Oxide Nanostructures from Non-Equilibrium Deposition Conditions

DTIC Science & Technology

2016-07-11

pressure and temperature in the chamber by a rough estimation using PV = nRT. The deposition area is the internal surface of the tubular chamber, D...J. Wang, L. Zhang, T.L. Andrew, M.S. Arnold, X.D. Wang “Development of Lead Iodide Perovskite Solar Cells Using Three-Dimensional Titanium Dioxide...Andrew, M.S. Arnold, X.D. Wang "Development of Lead Iodide Perovskite Solar Cells Using Three-Dimensional Titanium Dioxide Nanowire Architectures" ACS

Toxicity and Fate Comparison between Several Brass and Titanium Dioxide Powders

DTIC Science & Technology

1993-07-01

the entire gut without showing any apparent effects . 14. UBJET TEMS1I. NUMBER OF PAGES 27 Daphnia Algae EC50 Aquatic toxicity 11T.PRICE CODE 9...levels of soluble copper and zinc in solution. 3. RESULTS The titanium dioxide ( TiO2 ) materials did not show any apparent toxic effects to daphnia up to...The extended exposure did not show any apparent toxic effects . Long term effects on aquatic org.rnisms exposed to TiO2 are not known. It is apparent

Three Dimensional Reconstruction Algorithm for Imaging Pathophysiological Signals Within Breast Tissue Using Near Infrared Light

DTIC Science & Technology

2006-07-01

months.31 A heated mixture of water, gelatin (G2625, Sigma Inc.), India ink (for absorption), and titanium dioxide powder (for scatter) (TiO2, Sigma Inc...for absorption, and titanium dioxide powder for scat- ter TiO2, Sigma Inc. that are solidified by cooling to room temperature. Optically...2713-2727. 8. Bolin, F.P., Preuss, L. E., Taylor, R. C., Ference, R. J, Refractive index of some mammalian tissue using a fiber optic cladding method

Analysis of x-ray diffraction pattern and complex plane impedance plot of polypyrrole/titanium dioxide nanocomposite: A simulation study

NASA Astrophysics Data System (ADS)

Ravikiran, Y. T.; Vijaya Kumari, S. C.

2013-06-01

To innovate the properties of Polypyrrole/Titanium dioxide (PPy/TiO2) nanocomposite further, it has been synthesized by chemical polymerization technique. The nanostructure and monoclinic phase of the prepared composite have been confirmed by simulating the X-ray diffraction pattern (XRD). Also, complex plane impedance plot of the composite has been simulated to find equivalent resistance capacitance circuit (RC circuit) and numerical values of R and C have been predicted.

Van vleck paramagnetism in orthorhombic TiO2 (Brookite)

USGS Publications Warehouse

Senftle, F.E.; Thorpe, A.N.

1968-01-01

The magnetic susceptibility of the orthorhombic form of titanium dioxide has been measured from 5 to 300??K. After deducting the temperature-dependent component, which is probably due to defects or impurities, and the free-ion diamagnetic component, the Van Vleck paramagnetism was estimated to be 33??10-6 emu/mole. Comparison is made between this value and the Van Vleck paramagnetism of strontium titanate and the two tetragonal forms of titanium dioxide: rutile and anatase. ?? 1968 The American Physical Society.

Supported fischer-tropsch catalyst and method of making the catalyst

DOEpatents

Dyer, Paul N.; Pierantozzi, Ronald; Withers, Howard P.

1987-01-01

A Fischer-Tropsch catalyst and a method of making the catalyst for a Fischer-Tropsch process utilizing the catalyst by which synthesis gas, particularly carbon-monoxide rich synthesis gas, is selectively converted to higher hydrocarbons of relatively narrow carbon number range is disclosed. In general, the selective and notably stable catalyst, consist of an inert carrier first treated with a Group IV B metal compound (such as zirconium or titanium), preferably an alkoxide compound, and subsequently treated with an organic compound of a Fischer-Tropsch metal catalyst, such as cobalt, iron or ruthenium carbonyl. Reactions with air and water and calcination are specifically avoided in the catalyst preparation procedure.

Effect of preparation methods on the activity of titanium dioxide-carbon nitride composites for photocatalytic degradation of salicylic acid

NASA Astrophysics Data System (ADS)

Yuliati, L.; Salleh, A. M.; Hatta, M. H. M.; Lintang, H. O.

2018-04-01

In this study, titanium dioxide-carbon nitride (TiO2-CN) composites were prepared by three methods, which were one pot oxidation, impregnation, and physical mixing. Each series of the photocatalysts was prepared with different ratios of titanium to carbon (Ti/C), i.e., 1, 5, 10, 20, and 50 mol%. All samples were characterized by X-ray diffraction (XRD) and diffuse reflectance ultraviolet-visible (DR UV-Vis) spectroscopies. The characterization results confirmed the successful preparation of TiO2, CN, and the TiO2-CN composites. Photocatalytic activity tests were carried out for degradation of salicylic acid at room temperature for 6 h under UV and visible light irradiations. It was confirmed that all the prepared TiO2-CN composites showed better photocatalytic activities than the bare TiO2 and the bare CN. Under UV light irradiation, 90.6% of salicylic acid degradation was achieved on the best composite prepared by one pot oxidation with 5 mol% of titanium to carbon (Ti/C) ratio. On the other hand, the highest degradation under visible light irradiation was 94.3%, observed on the composite that was prepared also by one pot oxidation method with the Ti/C ratio of 10 mol%. Therefore, among the investigated methods, the best method to prepare the titanium dioxide-carbon nitride composites with high photocatalytic activity was one pot oxidation method.

Effect of molarity on sol-gel routed nano TiO2 thin films

NASA Astrophysics Data System (ADS)

Lourduraj, Stephen; Williams, Rayar Victor

The nanostructured titanium dioxide (TiO2) thin films have been prepared for the molar concentrations of titanium tetra isopropoxide (TTIP) 0.05M, 0.1M, 0.15M and 0.2M by sol-gel routed spin coating technique with calcination at 450∘C. The processing parameters such as, pH value (8), catalyst HCl (0.1ml), spin speed (3000rpm) and calcination temperature (450∘C) are optimized. The crystalline nature and surface morphology were analyzed by XRD, SEM and AFM analysis. The XRD results confirm that the films are crystalline with anatase phase, and are nanostructured. The SEM micrographs of the TiO2 film reveal the spherical nature of the particle. AFM analysis establishes that the uniformity of the TiO2 thin film was optimized at 0.2M. The optical measurements show that the transmittance depends on the molarity, and the optical band gap energy of TiO2 films is found to be inversely proportional to molarity. The I-V characteristics exhibit that the molarity strongly influences the electrical conductivity of the film. The results indicate that the significant effect of molarity on structural, optical and electrical properties of the nanostructured TiO2 thin films will be useful to photovoltaic application.

Facet-specific interaction between methanol and TiO2 probed by sum-frequency vibrational spectroscopy.

PubMed

Yang, Deheng; Li, Yadong; Liu, Xinyi; Cao, Yue; Gao, Yi; Shen, Y Ron; Liu, Wei-Tao

2018-04-24

The facet-specific interaction between molecules and crystalline catalysts, such as titanium dioxides (TiO 2 ), has attracted much attention due to possible facet-dependent reactivity. Using surface-sensitive sum-frequency vibrational spectroscopy, we have studied how methanol interacts with different common facets of crystalline TiO 2 , including rutile(110), (001), (100), and anatase(101), under ambient temperature and pressure. We found that methanol adsorbs predominantly in the molecular form on all of the four surfaces, while spontaneous dissociation into methoxy occurs preferentially when these surfaces become defective. Extraction of Fermi resonance coupling between stretch and bending modes of the methyl group in analyzing adsorbed methanol spectra allows determination of the methanol adsorption isotherm. The isotherms obtained for the four surfaces are nearly the same, yielding two adsorbed Gibbs free energies associated with two different adsorption configurations singled out by ab initio calculations. They are ( i ) ∼-20 kJ/mol for methanol with its oxygen attached to a low-coordinated surface titanium, and ( ii ) ∼-5 kJ/mol for methanol hydrogen-bonded to a surface oxygen and a neighboring methanol molecule. Despite similar adsorption energetics, the Fermi resonance coupling strength for adsorbed methanol appears to depend sensitively on the surface facet and coverage.

Surface bioactivity modification of titanium by CO 2 plasma treatment and induction of hydroxyapatite: In vitro and in vivo studies

NASA Astrophysics Data System (ADS)

Hu, Xixue; Shen, Hong; Shuai, Kegang; Zhang, Enwei; Bai, Yanjie; Cheng, Yan; Xiong, Xiaoling; Wang, Shenguo; Fang, Jing; Wei, Shicheng

2011-01-01

Since metallic biomaterials used for orthopedic and dental implants possess a paucity of reactive functional groups, bioactivity modification of these materials is challenging. In the present work, the titanium discs and rods were treated with carbon dioxide plasma and then incubated in a modified simulated body fluid 1.5SBF to obtain a hydroxyapatite layer. Surface hydrophilicity of samples, changes of surface chemistry, surface morphologies of samples, and structural analysis of formed hydroxyapatite were investigated by contact angle to water, X-ray photoelectron spectrometer (XPS), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The results demonstrated that hydrophilicity of titanium surface was improved and hydroxyl groups increased after modification with carbon dioxide plasma treatment. The hydroxyl groups on the surface of titanium were the richest after carbon dioxide plasma treatment under the condition of 20 W for less than 30 s. The hydroxyapatite formability of titanium surface was enhanced by carbon dioxide plasma pretreatment, which was attributed to the surface chemistry. MC3T3-E1 cell as a model cell was cultured on the Ti, CPT-Ti and CPT/SBF-Ti discs in vitro, and the results of the morphology and differentiation of the cell showed that CPT/SBF-Ti was the highest bioactive. The relative parameters of the new bone around the Ti and CPT/SBF-Ti rods including bone mineral density (BMD), a ratio of bone volume to total volume (BV/TV), trabecular thickness (Tb.Th.) and trabecular number (Tb.N.) were analyzed by a micro-computed tomography (micro-CT) after 4-, 8- and 12-week implantation periods in vivo. The results indicated that the CPT/SBF-Ti was more advantageous for new bone formation.

[An in vitro study on toxic effect of vanadium-titanium-magnetite dust on alveolar macrophage in rabbits].

PubMed

Song, Y; Chen, Q; Guan, Y

1998-11-01

To study the toxic effect of vanadium-titanium-magnetite (VTM) dust on alveolar macrophage (AM) and its hazardous extent. Survival rates, morphology and function of AM were compared in rabbits exposed to dust of VTM, vanadium oxide, titanium dioxide and silica in various doses and length of time with in vitro cell culture and putamen membrane cover glass transmission electron microscopy, and changes in activities of lactic dehydrogenase (LDH) and acid phosphatase (ACP) in cell culture were measured. Exposure to all the four kinds of dust could lead to decrease in survival rate of AM, increase in activities of LDH and ACP in the cell culture, and changes in their morphology and function to the extent dependent on the nature of dust. Toxic effect of exposure to VTM dust was lower than that to vanadium oxide and silica, but higher than that to titanium dioxide, which had slight toxic effect.

High-Performance Core–Shell Catalyst with Nitride Nanoparticles as a Core: Well-Defined Titanium Copper Nitride Coated with an Atomic Pt Layer for the Oxygen Reduction Reaction

DOE PAGES

Tian, Xinlong; Tang, Haibo; Luo, Junming; ...

2017-04-25

A class of core–shell structured low-platinum catalysts with well-dispersed inexpensive titanium copper nitride nanoparticles as cores and atomic platinum layers as shells exhibiting high activity and stability for the oxygen reduction reaction is successfully developed. In using nitrided carbon nanotubes (NCNTs) as the support greatly improved the morphology and dispersion of the nitride nanoparticles, resulting in significant enhancement of the performance of the catalyst. The optimized catalyst, Ti 0.9Cu 0.1N@Pt/NCNTs, has a Pt mass activity 5 times higher than that of commercial Pt/C, comparable to that of core–shell catalysts with precious metal nanoparticles as the core, and much higher thanmore » that the latter if we take into account the mass activity of all platinum group metals. Furthermore, only a minimal loss of activity can be observed after 10000 potential cycles, demonstrating the catalyst’s high stability. After durability testing, atomic-scale elemental mapping confirmed that the core–shell structure of the catalyst remained intact. This approach may open a pathway for the design and preparation of high-performance inexpensive core–shell catalysts for a wide range of applications in energy conversion processes.« less

High-Performance Core–Shell Catalyst with Nitride Nanoparticles as a Core: Well-Defined Titanium Copper Nitride Coated with an Atomic Pt Layer for the Oxygen Reduction Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Xinlong; Tang, Haibo; Luo, Junming

A class of core–shell structured low-platinum catalysts with well-dispersed inexpensive titanium copper nitride nanoparticles as cores and atomic platinum layers as shells exhibiting high activity and stability for the oxygen reduction reaction is successfully developed. In using nitrided carbon nanotubes (NCNTs) as the support greatly improved the morphology and dispersion of the nitride nanoparticles, resulting in significant enhancement of the performance of the catalyst. The optimized catalyst, Ti 0.9Cu 0.1N@Pt/NCNTs, has a Pt mass activity 5 times higher than that of commercial Pt/C, comparable to that of core–shell catalysts with precious metal nanoparticles as the core, and much higher thanmore » that the latter if we take into account the mass activity of all platinum group metals. Furthermore, only a minimal loss of activity can be observed after 10000 potential cycles, demonstrating the catalyst’s high stability. After durability testing, atomic-scale elemental mapping confirmed that the core–shell structure of the catalyst remained intact. This approach may open a pathway for the design and preparation of high-performance inexpensive core–shell catalysts for a wide range of applications in energy conversion processes.« less

Titanium dioxide thin films deposited by pulsed laser deposition and integration in radio frequency devices: Study of structure, optical and dielectric properties

NASA Astrophysics Data System (ADS)

Orlianges, Jean-Christophe; Crunteanu, Aurelian; Pothier, Arnaud; Merle-Mejean, Therese; Blondy, Pierre; Champeaux, Corinne

2012-12-01

Titanium dioxide presents a wide range of technological application possibilities due to its dielectric, electrochemical, photocatalytic and optical properties. The three TiO2 allotropic forms: anatase, rutile and brookite are also interesting, since they exhibit different properties, stabilities and growth modes. For instance, rutile has a high dielectric permittivity, of particular interest for the integration as dielectric in components such as microelectromechanical systems (MEMS) for radio frequency (RF) devices. In this study, titanium dioxide thin films are deposited by pulsed laser deposition. Characterizations by Raman spectroscopy and X-ray diffraction show the evolution of the structural properties. Thin films optical properties are investigated using spectroscopic ellipsometry and transmission measurements from UV to IR range. Co-planar waveguide (CPW) devices are fabricated based on these films. Their performances are measured in the RF domain and compared to simulation, leading to relative permittivity values in the range 30-120, showing the potentialities of the deposited material for capacitive switches applications.

Pulsed TEA CO2 Laser Irradiation of Titanium in Nitrogen and Carbon Dioxide Gases

NASA Astrophysics Data System (ADS)

Ciganovic, J.; Matavulj, P.; Trtica, M.; Stasic, J.; Savovic, J.; Zivkovic, S.; Momcilovic, M.

2017-12-01

Surface changes created by interaction of transversely excited atmospheric carbon dioxide (TEA CO2) laser with titanium target/implant in nitrogen and carbon dioxide gas were studied. TEA CO2 laser operated at 10.6 μm, pulse length of 100 ns and fluence of ˜17 J/cm2 which was sufficient for inducing surface modifications. Induced changes depend on the gas used. In both gases the grain structure was produced (central irradiated zone) but its forms were diverse, (N2: irregular shape; CO2: hill-like forms). Hydrodynamic features at peripheral zone, like resolidified droplets, were recorded only in CO2 gas. Elemental analysis of the titanium target surface indicated that under a nitrogen atmosphere surface nitridation occurred. In addition, irradiation in both gases was followed by appearance of plasma in front of the target. The existence of plasma indicates relatively high temperatures created above the target surface offering a sterilizing effect.

Catalysts for CO2/epoxide ring-opening copolymerization

PubMed Central

Trott, G.; Saini, P. K.; Williams, C. K.

2016-01-01

This article summarizes and reviews recent progress in the development of catalysts for the ring-opening copolymerization of carbon dioxide and epoxides. The copolymerization is an interesting method to add value to carbon dioxide, including from waste sources, and to reduce pollution associated with commodity polymer manufacture. The selection of the catalyst is of critical importance to control the composition, properties and applications of the resultant polymers. This review highlights and exemplifies some key recent findings and hypotheses, in particular using examples drawn from our own research. PMID:26755758

Synthesis of Titanium Oxycarbide from Titanium Slag by Methane-Containing Gas

NASA Astrophysics Data System (ADS)

Dang, Jie; Fatollahi-Fard, Farzin; Pistorius, Petrus Christiaan; Chou, Kuo-Chih

2018-02-01

In this study, reaction steps of a process for synthesis of titanium oxycarbide from titanium slag were demonstrated. This process involves the reduction of titanium slag by a methane-hydrogen-argon mixture at 1473 K (1200 °C) and the leaching of the reduced products by hydrofluoric acid near room temperature to remove the main impurity (Fe3Si). Some iron was formed by disproportionation of the main M3O5 phase before gaseous reduction started. Upon reduction, more iron formed first, followed by reduction of titanium dioxide to suboxides and eventually oxycarbide.

Visible light-harvesting photoanodes for solar energy conversion: A comparison of anchoring groups to titanium dioxide

NASA Astrophysics Data System (ADS)

Martini, Lauren A.

Environmental concerns related to climate change and geopolitical issues related to energy security have led to a widespread pursuit of alternative, non-fossil fuel energy sources capable of meeting our increasing global energy demands. Solar energy, which strikes the earth's surface at a rate vastly exceeding our current worldwide power demand, presents itself as a promising source of clean, abundant and renewable energy. The capture and conversion of solar energy into electricity as well as storable, transportable chemical fuels has therefore become major area of chemical research. Inspired by photosynthesis in nature, in which plants and algae convert sunlight, water, and carbon dioxide into oxygen and stored chemical fuel in the form of sugars, recent work has focused on visible light-driven water-splitting technologies for the production of solar fuels. Honda and Fujishima reported the first example of photoelectrochemical water oxidation in 1972. In their system, an inexpensive titanium dioxide semiconductor irradiated with ultraviolet light produced oxygen at the photoanode surface and hydrogen at the surface of a platinum counter electrode. In attempt to harness visible light instead, titanium dioxide and other inexpensive wide band gap photoanodes have been functionalized with visible light-absorbing molecular dyes. These dye-sensitized photoanodes have been used successfully to convert solar energy into electrical current, as in dye-sensitized solar cells, and to drive chemical processes like water oxidation, as in photocatalytic cells. In both systems, a long-lived charge separation is established upon illumination of the photoanode surface when a photoexcited molecular chromophore transfers an electron to the semiconductor conduction band. Following this electron injection process, a nearby redox-active species is oxidized and refills the hole left behind on the molecular chromophore. While the steps of this scheme are relatively straightforward, the integration of efficient visible-light absorption, ultrafast forward electron transfer, and stable charge separation is quite complicated. The work presented here is devoted to the design, synthesis, spectroscopy, and computational study of dye-sensitized photoanodes. In particular, we explore the relative stability and performance of different anchoring groups for the surface attachment of light-harvesting molecular dyes to titanium dioxide. Here we present the first systematic study that directly compares carboxylate, phosphonate, acetylacetonate, and hydroxamate anchors using the same molecular chromophore framework. We discuss a number of novel methods for the incorporation of anchoring group functionalities on each chromophore framework. We also assess the relative water stability of each of the anchoring groups on titanium dioxide as well as the relative efficiency of electron transfer from photoexcited molecular chromophores through each anchoring group into the conduction band of titanium dioxide. We hope that the work presented here will contribute to the rational design of better photoanodes for light-driven water splitting.

Development of a ruthenium/phosphite catalyst system for domino hydroformylation-reduction of olefins with carbon dioxide.

PubMed

Liu, Qiang; Wu, Lipeng; Fleischer, Ivana; Selent, Detlef; Franke, Robert; Jackstell, Ralf; Beller, Matthias

2014-06-02

An efficient domino ruthenium-catalyzed reverse water-gas-shift (RWGS)-hydroformylation-reduction reaction of olefins to alcohols is reported. Key to success is the use of specific bulky phosphite ligands and triruthenium dodecacarbonyl as the catalyst. Compared to the known ruthenium/chloride system, the new catalyst allows for a more efficient hydrohydroxymethylation of terminal and internal olefins with carbon dioxide at lower temperature. Unwanted hydrogenation of the substrate is prevented. Preliminary mechanism investigations uncovered the homogeneous nature of the active catalyst and the influence of the ligand and additive in individual steps of the reaction sequence. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Methods of producing epoxides from alkenes using a two-component catalyst system

DOEpatents

Kung, Mayfair C.; Kung, Harold H.; Jiang, Jian

2013-07-09

Methods for the epoxidation of alkenes are provided. The methods include the steps of exposing the alkene to a two-component catalyst system in an aqueous solution in the presence of carbon monoxide and molecular oxygen under conditions in which the alkene is epoxidized. The two-component catalyst system comprises a first catalyst that generates peroxides or peroxy intermediates during oxidation of CO with molecular oxygen and a second catalyst that catalyzes the epoxidation of the alkene using the peroxides or peroxy intermediates. A catalyst system composed of particles of suspended gold and titanium silicalite is one example of a suitable two-component catalyst system.

Chemistry of Non-Equilibrium Film Deposition.

DTIC Science & Technology

1985-12-01

titanium isopropoxide mixed with water solutions of lanthanum and lead nitrate. The gels were dehydrated, then fired to 600C to remove all organics...OW- ’so IRO $Va. ame Thin films; titanium dioxide; -PuZT,- ion beam deposition; annealing,’ trnmiso electron microscopy. 4 - . - S \\AISST 0A ZT *Can...Deposition....... . ... *.... .. ... .. ..... .. . .... 2 C. Nonequilibrium Physical Deposition.................... 3 1. Titanium Oxide Films

Crystalline titanate catalyst supports

DOEpatents

Anthony, R.G.; Dosch, R.G.

1993-01-05

A series of new crystalline titanates (CT) are shown to have considerable potential as catalyst supports. For Pd supported catalyst, the catalytic activity for pyrene hydrogenation was substantially different depending on the type of CT, and one was substantially more active than Pd on hydrous titanium oxide (HTO). For 1-hexene hydrogenation the activities of the new CTs were approximately the same as for the hydrous metal oxide supports.

Crystalline titanate catalyst supports

DOEpatents

Anthony, Rayford G.; Dosch, Robert G.

1993-01-01

A series of new crystalline titanates (CT) are shown to have considerable potential as catalyst supports. For Pd supported catalyst, the catalytic activity for pyrene hydrogenation was substantially different depending on the type of CT, and one was substantially more active than Pd on hydrous titanium oxide (HTO). For 1-hexene hydrogenation the activities of the new CTs were approximately the same as for the hydrous metal oxide supports.

Catalyst for selective conversion of synthesis gas and method of making the catalyst

DOEpatents

Dyer, Paul N.; Pierantozzi, Ronald

1986-01-01

A Fischer-Tropsch (F-T) catalyst, a method of making the catalyst and an F-T process utilizing the catalyst by which synthesis gas, particularly carbon-monoxide rich synthesis gas is selectively converted to higher hydrocarbons of relatively narrow carbon number range. In general, the selective and notably stable catalyst, consists of an inert carrier first treated with a Group IV B metal compound (such as zirconium or titanium), preferably an alkoxide compound, and subsequently treated with an organic compound of an F-T metal catalyst, such as cobalt, iron or ruthenium carbonyl. Reactions with air and water and calcination are specifically avoided in the catalyst preparation procedure.

Negative surface streamers propagating on TiO2 and γ-Al2O3-supported Ag catalysts: ICCD imaging and modeling study

NASA Astrophysics Data System (ADS)

Kim, Hyun-Ha; Teramoto, Yoshiyuki; Ogata, Atsushi; Kang, Woo Seok; Hur, Min; Song, Young-Hoon

2018-06-01

Surface streamers propagating on the surface of titanium dioxide (TiO2) and alumina (γ-Al2O3) were studied in negative polarity using intensified charge coupled device (ICCD) imaging and numerical simulation. Detailed time-resolved ICCD images of cathode-directed streamers (CDSs) emanating from a ground electrode are first presented in this report. Instead of primary streamers in positive polarity, only a glow-like discharge appeared in the early stage at the cathode under negative polarity. After this discharge disappeared, a counter-propagating CDS initiated from the ground electrode (anode). Numerical simulation indicated that strong electric fields at the pellet-anode and the formation of positive ion rich local spots were the main reason for the CDS formation near the ground electrode. The maximum velocity was 750 km s‑1 for Ag-supported γ-Al2O3 and 550 km s‑1 for Ag-supported TiO2, respectively. In contrast to the CDS in the gas-phase with a positive polarity, the CDS in a catalyst packed-bed under negative polarity showed more branching and a larger number of streamers in the presence of oxygen than in pure N2.

Improving the efficiency of water splitting in dye-sensitized solar cells by using a biomimetic electron transfer mediator

PubMed Central

Zhao, Yixin; Swierk, John R.; Megiatto, Jackson D.; Sherman, Benjamin; Youngblood, W. Justin; Qin, Dongdong; Lentz, Deanna M.; Moore, Ana L.; Moore, Thomas A.; Gust, Devens; Mallouk, Thomas E.

2012-01-01

Photoelectrochemical water splitting directly converts solar energy to chemical energy stored in hydrogen, a high energy density fuel. Although water splitting using semiconductor photoelectrodes has been studied for more than 40 years, it has only recently been demonstrated using dye-sensitized electrodes. The quantum yield for water splitting in these dye-based systems has, so far, been very low because the charge recombination reaction is faster than the catalytic four-electron oxidation of water to oxygen. We show here that the quantum yield is more than doubled by incorporating an electron transfer mediator that is mimetic of the tyrosine-histidine mediator in Photosystem II. The mediator molecule is covalently bound to the water oxidation catalyst, a colloidal iridium oxide particle, and is coadsorbed onto a porous titanium dioxide electrode with a Ruthenium polypyridyl sensitizer. As in the natural photosynthetic system, this molecule mediates electron transfer between a relatively slow metal oxide catalyst that oxidizes water on the millisecond timescale and a dye molecule that is oxidized in a fast light-induced electron transfer reaction. The presence of the mediator molecule in the system results in photoelectrochemical water splitting with an internal quantum efficiency of approximately 2.3% using blue light. PMID:22547794

Bare TiO2 and graphene oxide TiO2 photocatalysts on the degradation of selected pesticides and influence of the water matrix

NASA Astrophysics Data System (ADS)

Cruz, Marta; Gomez, Cristina; Duran-Valle, Carlos J.; Pastrana-Martínez, Luisa M.; Faria, Joaquim L.; Silva, Adrián M. T.; Faraldos, Marisol; Bahamonde, Ana

2017-09-01

The photocatalytic activity of a home-made titanium dioxide (TiO2) and its corresponding composite based on graphene oxide (GO), the GO-TiO2 catalyst, has been investigated under UV-vis in the photodegradation of a mixture of four pesticides classified by the European Union as priority pollutants: diuron, alachlor, isoproturon and atrazine. The influence of two water matrices (ultrapure or natural water) was also studied. Natural water led to a decrease on the degradation of the studied pollutants when the bare TiO2 photocatalyst was employed, since this water contains both inorganic and organic species that are dissolved and commonly restrain the photocatalytic process. On the contrary, the photo-efficiency of the GO-TiO2 composite seems to be less affected by water matrix variation, with very good initial pesticide photodegradation rates under both natural and ultrapure water matrices. A comparative study between GO-TiO2 and the commercial Evonik TiO2 P25 catalyst was also carried out to analyze the photocatalytic degradation of these pesticides under visible light illumination conditions. Once again, a higher photocatalytic activity was found for the GO-TiO2 composite.

Possibilities of surface coating for thermal insulation. [zirconium dioxide, titanium dioxide, and zircon coatings

NASA Technical Reports Server (NTRS)

Poeschel, E.; Weisser, G.

1979-01-01

Calculations performed for pulsating heat sources indicate a relatively thin (200-1000 micron) coating can lower temperature both inside and on the surface of a construction material. Various coating materials (including zirconium dioxide) are discussed, together with possible thermic stresses and ways to deal with the latter.

Catalyzed borohydrides for hydrogen storage

DOEpatents

Au, Ming [Augusta, GA

2012-02-28

A hydrogen storage material and process is provided in which alkali borohydride materials are created which contain effective amounts of catalyst(s) which include transition metal oxides, halides, and chlorides of titanium, zirconium, tin, and combinations of the various catalysts. When the catalysts are added to an alkali borodydride such as a lithium borohydride, the initial hydrogen release point of the resulting mixture is substantially lowered. Additionally, the hydrogen storage material may be rehydrided with weight percent values of hydrogen at least about 9 percent.

Perovskite catalysts for oxidative coupling

DOEpatents

Campbell, K.D.

1991-06-25

Perovskites of the structure A[sub 2]B[sub 2]C[sub 3]O[sub 10] are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

Perovskite catalysts for oxidative coupling

DOEpatents

Campbell, Kenneth D.

1991-01-01

Perovskites of the structure A.sub.2 B.sub.2 C.sub.3 O.sub.10 are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

Cobalt and Yttrium Modified TiO2 Nanotubes Based Dye-Sensitized Solar Cells for Solar-Energy Conversion

NASA Astrophysics Data System (ADS)

Shabanov, N. S.; Isaev, A. B.; Orudzhev, F. F.; Murliev, E. K.

2018-01-01

The solar-energy conversion in eosin-sensitized solar cells based on cobalt and yttrium modified TiO2 nanotubes has been studied.It is established that the doping with metal ions shifts the absorption edge for Co and Y doped titanium dioxide samples to longer and shorter wavelengths, respectively. The efficiency of solar energy conversion depends on the wide bandgap of the semiconductor anode and reaches a maximum (4.4%) for yttrium-doped TiO2 in comparison to that (4.1%) for pure titanium dioxide.

A clean-up method by photocatalysis for HPLC analysis of iprodione in dry basil.

PubMed

Maeda, Osamu; Oikawa, Chie; Shiomi, Nobuo; Toriba, Akira; Hayakawa, Kazuichi

2008-08-01

Titanium dioxide was used as a photocatalyst to decompose interfering substances for a quantitative analysis of a fungicide (iprodione) in dry basil by HPLC. A quartz vial containing basil extract and titanium dioxide was irradiated with black light. The interfering substances were almost completely decomposed by 180 min of irradiation, whereas 88.3% of iprodione remained. The recovery of iprodione was 102.6% by the proposed method in basil extracts. This may have been due to different decomposition rates of the analyte and interfering substances.

Effect of Oxide Coating on Performance of Copper-Zinc Oxide-Based Catalyst for Methanol Synthesis via Hydrogenation of Carbon Dioxide.

PubMed

Umegaki, Tetsuo; Kojima, Yoshiyuki; Omata, Kohji

2015-11-16

The effect of oxide coating on the activity of a copper-zinc oxide-based catalyst for methanol synthesis via the hydrogenation of carbon dioxide was investigated. A commercial catalyst was coated with various oxides by a sol-gel method. The influence of the types of promoters used in the sol-gel reaction was investigated. Temperature-programmed reduction-thermogravimetric analysis revealed that the reduction peak assigned to the copper species in the oxide-coated catalysts prepared using ammonia shifts to lower temperatures than that of the pristine catalyst; in contrast, the reduction peak shifts to higher temperatures for the catalysts prepared using L(+)-arginine. These observations indicated that the copper species were weakly bonded with the oxide and were easily reduced by using ammonia. The catalysts prepared using ammonia show higher CO₂ conversion than the catalysts prepared using L(+)-arginine. Among the catalysts prepared using ammonia, the silica-coated catalyst displayed a high activity at high temperatures, while the zirconia-coated catalyst and titania-coated catalyst had high activity at low temperatures. At high temperature the conversion over the silica-coated catalyst does not significantly change with reaction temperature, while the conversion over the zirconia-coated catalyst and titania-coated catalyst decreases with reaction time. From the results of FTIR, the durability depends on hydrophilicity of the oxides.

Effect of Oxide Coating on Performance of Copper-Zinc Oxide-Based Catalyst for Methanol Synthesis via Hydrogenation of Carbon Dioxide

PubMed Central

Umegaki, Tetsuo; Kojima, Yoshiyuki; Omata, Kohji

2015-01-01

The effect of oxide coating on the activity of a copper-zinc oxide–based catalyst for methanol synthesis via the hydrogenation of carbon dioxide was investigated. A commercial catalyst was coated with various oxides by a sol-gel method. The influence of the types of promoters used in the sol-gel reaction was investigated. Temperature-programmed reduction-thermogravimetric analysis revealed that the reduction peak assigned to the copper species in the oxide-coated catalysts prepared using ammonia shifts to lower temperatures than that of the pristine catalyst; in contrast, the reduction peak shifts to higher temperatures for the catalysts prepared using L(+)-arginine. These observations indicated that the copper species were weakly bonded with the oxide and were easily reduced by using ammonia. The catalysts prepared using ammonia show higher CO2 conversion than the catalysts prepared using L(+)-arginine. Among the catalysts prepared using ammonia, the silica-coated catalyst displayed a high activity at high temperatures, while the zirconia-coated catalyst and titania-coated catalyst had high activity at low temperatures. At high temperature the conversion over the silica-coated catalyst does not significantly change with reaction temperature, while the conversion over the zirconia-coated catalyst and titania-coated catalyst decreases with reaction time. From the results of FTIR, the durability depends on hydrophilicity of the oxides. PMID:28793674

Method for preparing hydrous titanium oxide spherules and other gel forms thereof

DOEpatents

Collins, J.L.

1998-10-13

The present invention are methods for preparing hydrous titanium oxide spherules, hydrous titanium oxide gels such as gel slabs, films, capillary and electrophoresis gels, titanium monohydrogen phosphate spherules, hydrous titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite sorbent, titanium monohydrogen phosphate spherules having suspendible particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, titanium oxide spherules in the form of anatase, brookite or rutile, titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite, hydrous titanium oxide fiber materials, titanium oxide fiber materials, hydrous titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite, titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite and spherules of barium titanate. These variations of hydrous titanium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters and ceramics. 6 figs.

Method for preparing hydrous titanium oxide spherules and other gel forms thereof

DOEpatents

Collins, Jack L.

1998-01-01

The present invention are methods for preparing hydrous titanium oxide spherules, hydrous titanium oxide gels such as gel slabs, films, capillary and electrophoresis gels, titanium monohydrogen phosphate spherules, hydrous titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite sorbent, titanium monohydrogen phosphate spherules having suspendible particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, titanium oxide spherules in the form of anatase, brookite or rutile, titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite, hydrous titanium oxide fiber materials, titanium oxide fiber materials, hydrous titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite, titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite and spherules of barium titanate. These variations of hydrous titanium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters and ceramics.

Complex compound polyvinyl alcohol-titanic acid/titanium dioxide

NASA Astrophysics Data System (ADS)

Prosanov, I. Yu.

2013-02-01

A complex compound polyvinyl alcohol-titanic acid has been produced and investigated by means of IR and Raman spectroscopy, X-ray diffraction, and synchronous thermal analysis. It is claimed that it represents an interpolymeric complex of polyvinyl alcohol and hydrated titanium oxide.

Catalytic metathesis of carbon dioxide with heterocumulenes mediated by titanium isopropoxide.

PubMed

Ghosh, Rajshekhar; Samuelson, Ashoka G

2005-04-21

The insertion of an isopropoxide ligand of titanium isopropoxide into heterocumulenes gives a product that carries out metathesis at elevated temperatures by undergoing insertion of a second heterocumulene in a head to head fashion, followed by an extrusion reaction.

Oxygen-Barrier Coating for Titanium

NASA Technical Reports Server (NTRS)

Clark, Ronald K.; Unnam, Jalaiah

1987-01-01

Oxygen-barrier coating for titanium developed to provide effective and low-cost means for protecting titanium alloys from oxygen in environment when alloys used in high-temperature mechanical or structural applications. Provides protective surface layer, which reduces extent of surface oxidation of alloy and forms barrier to diffusion of oxygen, limiting contamination of substrate alloy by oxygen. Consists of submicron layer of aluminum deposited on surface of titanium by electron-beam evaporation, with submicron layer of dioxide sputtered onto aluminum to form coat.

Conducting metal oxide and metal nitride nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiSalvo, Jr., Francis J.; Subban, Chinmayee V.

Conducting metal oxide and nitride nanoparticles that can be used in fuel cell applications. The metal oxide nanoparticles are comprised of for example, titanium, niobium, tantalum, tungsten and combinations thereof. The metal nitride nanoparticles are comprised of, for example, titanium, niobium, tantalum, tungsten, zirconium, and combinations thereof. The nanoparticles can be sintered to provide conducting porous agglomerates of the nanoparticles which can be used as a catalyst support in fuel cell applications. Further, platinum nanoparticles, for example, can be deposited on the agglomerates to provide a material that can be used as both an anode and a cathode catalyst supportmore » in a fuel cell.« less

W-containing oxide layers obtained on aluminum and titanium by PEO as catalysts in thiophene oxidation

NASA Astrophysics Data System (ADS)

Rudnev, V. S.; Lukiyanchuk, I. V.; Vasilyeva, M. S.; Morozova, V. P.; Zelikman, V. M.; Tarkhanova, I. G.

2017-11-01

W-containing oxide layers fabricated on titanium and aluminum alloys by Plasma electrolytic oxidation (PEO) have been tested in the reaction of the peroxide oxidation of thiophene. Samples with two types of coatings have been investigated. Coatings I contained tungsten oxide in the matrix and on the surface of amorphous silica-titania or silica-alumina layers, while coatings II comprised crystalline WO3 and/or Al2(WO4)3. Aluminum-supported catalyst containing a smallest amount of transition metals in the form of tungsten oxides and manganese oxides in low oxidation levels showed high activity and stability.

Application of a Heterogeneous Chiral Titanium Catalyst Derived from Silica-Supported 3-Aryl H8-BINOL to Enantioselective Alkylation and Arylation of Aldehydes.

PubMed

Akai, Junichiro; Watanabe, Satoshi; Michikawa, Kumiko; Harada, Toshiro

2017-07-07

A 3-aryl H 8 -BINOL was grafted on the surface of silica gel using a hydrosilane derivative as a precursor, and the resulting silica-supported ligand (6 mol %) was employed in the enantioselective alkylation and arylation of aldehydes in the presence of Ti(O i Pr) 4 . The reactions using Et 2 Zn, Et 3 B, and aryl Grignard reagents all afforded the corresponding adducts in high enantioselectivities and yields. The silica-immobilized titanium catalyst could be reused up to 14 times without appreciable deterioration of the activity.

Sol-gel synthesis and optical properties of titanium dioxide thin film

NASA Astrophysics Data System (ADS)

Ullah, Irfan; Khattak, Shaukat Ali; Ahmad, Tanveer; Saman; Ludhi, Nayab Ali

2018-03-01

The titanium dioxide (TiO2) is synthesized by sol-gel method using titanium-tetra-iso-propoxide (TTIP) as a starting material, and deposited on the pre-cleaned glass substrate using spin coating technique at optimized parameters. Energy dispersive X-ray (EDX) spectroscopy confirms successful TiO2 growth. The optical properties concerning the transmission and absorption spectra show 85% transparency and 3.28 eV wide optical band gap for indirect transition, calculated from absorbance. The exponential behavior of absorption edge is observed and attributed to the localized states electronic transitions, curtailed in the indirect band gap of the thin film. The film reveals decreasing refractive index with increasing wavelength. The photoluminescence (PL) study ascertains that luminescent properties are due to the surface defects.

Versatile Titanium Silicide Monolayers with Prominent Ferromagnetic, Catalytic, and Superconducting Properties: Theoretical Prediction.

PubMed

Wu, Qisheng; Zhang, Jun-Jie; Hao, Peipei; Ji, Zhongyang; Dong, Shuai; Ling, Chongyi; Chen, Qian; Wang, Jinlan

2016-10-06

On the basis of global structure search and density functional theory calculations, we predict a new class of two-dimensional (2D) materials, titanium silicide (Ti 2 Si, TiSi 2 , and TiSi 4 ) monolayers. They are proved to be energetically, dynamically, and thermally stable and own excellent mechanical properties. Among them, Ti 2 Si is a ferromagnetic metal with a magnetic moment of 1.37 μ B /cell, while TiSi 2 is an ideal catalyst for the hydrogen evolution reaction with a nearly zero free energy of hydrogen adsorption. More importantly, electron-phonon coupling calculations suggest that TiSi 4 is a robust 2D phonon-mediated superconductor with a transition temperature of 5.8 K, and the transition temperature can be enhanced up to 11.7 K under a suitable external strain. The versatility makes titanium silicide monolayers promising candidates for spintronic materials, hydrogen evolution catalysts, and 2D superconductors.

Fischer-Tropsch activity for non-promoted cobalt-on-alumina catalysts

DOEpatents

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2001-01-01

Cobalt catalysts, and processes employing these inventive catalysts, for hydrocarbon synthesis. The inventive catalyst comprises cobalt on an alumina support and is not promoted with any noble or near noble metals. In one aspect of the invention, the alumina support preferably includes a dopant in an amount effective for increasing the activity of the inventive catalyst. The dopant is preferably a titanium dopant. In another aspect of the invention, the cobalt catalyst is preferably reduced in the presence of hydrogen at a water vapor partial pressure effective to increase the activity of the cobalt catalyst for hydrocarbon synthesis. The water vapor partial pressure is preferably in the range of from 0 to about 0.1 atmospheres.

Non-carbon titanium cobalt nitride nanotubes supported platinum catalyst with high activity and durability for methanol oxidation reaction

NASA Astrophysics Data System (ADS)

Chen, Xiaoxiang; Li, Wuyi; Pan, Zhanchang; Xu, Yanbin; Liu, Gen; Hu, Guanghui; Wu, Shoukun; Li, Jinghong; Chen, Chun; Lin, Yingsheng

2018-05-01

Titanium cobalt nitride nanotubes (Ti0.95Co0.05N NTs) hybrid support, a novel robust non-carbon support material prepared by solvothermal and post-nitriding processes, is further decorated with Pt nanoparticles for the electrooxidation of methanol. The catalyst is characterized by X-ray diffraction (XRD), nitrogen adsorption/desorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. The morphology, structure and composition of the synthesized Ti0.95Co0.05N NTs suggest that the nanotube wall is porous and consists of homogeneous cohesively attached nitrides nanocube particles. Notable, Ti0.95Co0.05N NTs supported Pt catalyst exhibits significantly improved catalytic activity and durability for methanol electrooxidation compared with the conventional JM Pt/C catalyst. The experimental data indicate that enhanced catalytic activity and stability of Pt/Ti0.95Co0.05N NTs towards methanol electrooxidation might be mainly attributed to the tubular nanostructures and synergistic effect introduced by the Co doping. Both of them are playing an important role in improving the activity and durability of the Ti0.95Co0.05N NTs catalyst.

Fischer-Tropsch Catalysts

NASA Technical Reports Server (NTRS)

White, James H. (Inventor); Taylor, Jesse W. (Inventor)

2008-01-01

Catalyst compositions and methods for F-T synthesis which exhibit high CO conversion with minor levels (preferably less than 35% and more preferably less than 5%) or no measurable carbon dioxide generation. F-T active catalysts are prepared by reduction of certain oxygen deficient mixed metal oxides.

Titanium: light, strong, and white

USGS Publications Warehouse

Woodruff, Laurel; Bedinger, George

2013-01-01

Titanium (Ti) is a strong silver-gray metal that is highly resistant to corrosion and is chemically inert. It is as strong as steel but 45 percent lighter, and it is twice as strong as aluminum but only 60 percent heavier. Titanium dioxide (TiO2) has a very high refractive index, which means that it has high light-scattering ability. As a result, TiO2 imparts whiteness, opacity, and brightness to many products. ...Because of the unique physical properties of titanium metal and the whiteness provided by TiO2, titanium is now used widely in modern industrial societies.

Controlled synthesis of titania using water-soluble titanium complexes: A review

NASA Astrophysics Data System (ADS)

Truong, Quang Duc; Dien, Luong Xuan; Vo, Dai-Viet N.; Le, Thanh Son

2017-07-01

The development of human society has led to the increase in energy and resources consumption as well as the arising problems of environmental damage and the toxicity to the human health. The development of novel synthesis method which tolerates utilization of toxic solvents and chemicals would fulfill the demand of the society for safer, softer, and environmental friendly technologies. For the past decades, a remarkable progress has been attained in the development of new water-soluble titanium complexes (WSTC) and their use for the synthesis of nanocrystalline titanium dioxide materials by aqueous solution-based approaches. The progress of synthesis of nanocrystalline titanium dioxide using such WSTCs is reviewed in this work. The key structural features responsible for the successfully controlled synthesis of TiO2 are discussed to provide guidelines for the morphology-controlled synthesis. Finally, this review ends with a summary and some perspectives on the challenges as well as new directions in this fascinating research.

Development and characterization of multilayer films of polyaniline, titanium dioxide and CTAB for potential antimicrobial applications.

PubMed

Farias, Emanuel Airton O; Dionisio, Natália A; Quelemes, Patrick V; Leal, Sergio Henrique; Matos, José Milton E; Silva Filho, Edson C; Bechtold, Ivan H; Leite, José Roberto S A; Eiras, Carla

2014-02-01

Composites prepared from polyaniline (PANI) and the ceramic technology of titanium dioxide (TiO2) have been proposed, however, the interaction of these materials with greater control of molecular arrangement becomes attractive in order to achieve properties not previously described or yet the optimization of those already reported. Therefore, in this study, thin hybrid films made of polyaniline (PANI), a conductive polymer, and the technological ceramic, titanium dioxide (TiO2), were prepared by the layer-by-layer (LbL) self-assembly technique. The films were characterized by cyclic voltammetry (CV), UV-VIS spectroscopy and atomic force microscopy (AFM). Aiming to improve the dispersion of the ceramic in the polymer matrix, the commercial surfactant, cetyl trimethylammonium bromide (CTAB), was used in the formation of the films. The best condition of deposition was found showing synergic interactions between the conjugated materials. The antibacterial activity of the PANI(TiO2)/CTAB films was studied and the obtained results suggest their use as antimicrobial coatings. Copyright © 2013 Elsevier B.V. All rights reserved.

Laboratory Study on the Fatigue Resistance of Asphaltic Concrete Containing Titanium Dioxide

NASA Astrophysics Data System (ADS)

Buhari, Rosnawati; Ezree Abdullah, Mohd; Khairul Ahmad, Mohd; Azhar Tajudin, Saiful; Khatijah Abu Bakar, Siti

2018-03-01

This study aims to evaluate the fatigue performance of modified asphalt mixture using Indirect Tensile Fatigue Test. Titanium Dioxide (TiO2) powder in a form of rutile was used for producing asphalt concrete with lower mixing and compaction temperature compared to conventional hot mix asphalt without reducing its physical and mechanical also resistance to fatigue. The characteristic of the asphalt and modified asphalt was evaluated using penetration test, softening test and rotational viscosity test. Titanium dioxide of 2%, 4%, 6%, 8% and 10% by weight of asphalt has been incorporated into unaged 80/100 asphalt mix in order to improvise its performance and to fulfill the objectives of this experimental study. As a result, TiO2 as an additive is potential to decrease the penetration and increasing the softening point of the asphalt. In terms of fatigue performance testing, addition TiO2 additive does help in improving the fatigue properties as it shows greater result than the control asphalt. In conclusion, TiO2 is great in improving fatigue properties.

Influence of adsorbents in transdermal matrix patches on the release and the physical state of ethinyl estradiol and levonorgestrel.

PubMed

Schulz, Martin; Fussnegger, Bernhard; Bodmeier, Roland

2011-02-01

The drug release from medium molecular weight polyisobutene patches containing adsorbates (drug content: 0.2% ethinyl estradiol, 1.0% levonorgestrel; adsorbent content: 20%, w/w) increased in the order of no adsorbent

Titanium dioxide thin films by atomic layer deposition: a review

NASA Astrophysics Data System (ADS)

Niemelä, Janne-Petteri; Marin, Giovanni; Karppinen, Maarit

2017-09-01

Within its rich phase diagram titanium dioxide is a truly multifunctional material with a property palette that has been shown to span from dielectric to transparent-conducting characteristics, in addition to the well-known catalytic properties. At the same time down-scaling of microelectronic devices has led to an explosive growth in research on atomic layer deposition (ALD) of a wide variety of frontier thin-film materials, among which TiO2 is one of the most popular ones. In this topical review we summarize the advances in research of ALD of titanium dioxide starting from the chemistries of the over 50 different deposition routes developed for TiO2 and the resultant structural characteristics of the films. We then continue with the doped ALD-TiO2 thin films from the perspective of dielectric, transparent-conductor and photocatalytic applications. Moreover, in order to cover the latest trends in the research field, both the variously constructed TiO2 nanostructures enabled by ALD and the Ti-based hybrid inorganic-organic films grown by the emerging ALD/MLD (combined atomic/molecular layer deposition) technique are discussed.

The potential use of nanosilver-decorated titanium dioxide nanofibers for toxin decomposition with antimicrobial and self-cleaning properties

NASA Astrophysics Data System (ADS)

Srisitthiratkul, Chutima; Pongsorrarith, Voraluck; Intasanta, Narupol

2011-08-01

While chemical and biological attacks pose risk to human health, clean air is of scientific, environmental and physiological concerns. In the present contribution, the potential use of nanosilver-decorated titanium dioxide (TiO 2) nanofibers for toxin decomposition with antimicrobial activity and self-cleaning properties was investigated. Titanium dioxide nanofibers were prepared through sol-gel reaction followed by an electrospinning process. Following the Japan Industrial Standard (JIS) protocol, decompositions of nitrogen oxide (NOx) and volatile organic compound (VOC) by the TiO 2 nanofibers suggested that these materials were capable of air treatment. To further enhance their anti-microbial activity, silver nanoparticles were decorated onto the TiO 2 nanofibers' surfaces via photoreduction of silver ion in the presence of the nanofibers suspension. Furthermore, tests of photocatalytic activity of the samples were performed by photodegrading methylene blue in water. The nanofibrous membranes prepared from these nanofibers showed superhydrophilicity under UV. Finally, the possibility of using these hybrid nanofibers in environmental and hygienic nanofiltration was proposed, where the self-cleaning characteristics was expected to be valuable in maintenance processes.

Electric field induced structural colour tuning of a silver/titanium dioxide nanoparticle one-dimensional photonic crystal

PubMed Central

Aluicio-Sarduy, Eduardo; Callegari, Simone; Figueroa del Valle, Diana Gisell; Desii, Andrea; Kriegel, Ilka

2016-01-01

Summary An electric field is employed for the active tuning of the structural colour in photonic crystals, which acts as an effective external stimulus with an impact on light transmission manipulation. In this work, we demonstrate structural colour in a photonic crystal device comprised of alternating layers of silver nanoparticles and titanium dioxide nanoparticles, exhibiting spectral shifts of around 10 nm for an applied voltage of only 10 V. The accumulation of charge at the metal/dielectric interface with an applied electric field leads to an effective increase of the charges contributing to the plasma frequency in silver. This initiates a blue shift of the silver plasmon band with a simultaneous blue shift of the photonic band gap as a result of the change in the silver dielectric function (i.e. decrease of the effective refractive index). These results are the first demonstration of active colour tuning in silver/titanium dioxide nanoparticle-based photonic crystals and open the route to metal/dielectric-based photonic crystals as electro-optic switches. PMID:27826514

Electric field induced structural colour tuning of a silver/titanium dioxide nanoparticle one-dimensional photonic crystal.

PubMed

Aluicio-Sarduy, Eduardo; Callegari, Simone; Figueroa Del Valle, Diana Gisell; Desii, Andrea; Kriegel, Ilka; Scotognella, Francesco

2016-01-01

An electric field is employed for the active tuning of the structural colour in photonic crystals, which acts as an effective external stimulus with an impact on light transmission manipulation. In this work, we demonstrate structural colour in a photonic crystal device comprised of alternating layers of silver nanoparticles and titanium dioxide nanoparticles, exhibiting spectral shifts of around 10 nm for an applied voltage of only 10 V. The accumulation of charge at the metal/dielectric interface with an applied electric field leads to an effective increase of the charges contributing to the plasma frequency in silver. This initiates a blue shift of the silver plasmon band with a simultaneous blue shift of the photonic band gap as a result of the change in the silver dielectric function (i.e. decrease of the effective refractive index). These results are the first demonstration of active colour tuning in silver/titanium dioxide nanoparticle-based photonic crystals and open the route to metal/dielectric-based photonic crystals as electro-optic switches.

Experimental evidence of {alpha}-olefin readsorption in Fischer-Tropsch synthesis on ruthenium-supported ETS-10 titanium silicate catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bianchi, C.L.; Ragaini, V.

1997-05-01

Fischer-Tropsch synthesis seems to develop the following two consecutive paths: a primary process that involves the formation of {alpha}-olefin products and a secondary process leading to the production of branched isomers and paraffins and requiring the readsorption of primary {alpha}-olefin products. It was already shown by Iglesia et al. that such readsorption steps are of fundamental importance for Ru catalysts and that they occur due to the slow diffusive removal of {alpha}-olefins when the molecular size increases, this resulting in a long intraparticle residence time. In the present paper {alpha}-olefins readsorption was enhanced by changing the metal distribution inside themore » pores of a titanium silicate (ETS-10), modified by ion exchange with alkali metal ions, used as a support for Ru-based catalysts. 24 refs., 5 figs., 3 tabs.« less

Catalytic transformation of carbon dioxide and methane into syngas over ruthenium and platinum supported hydroxyapatites

NASA Astrophysics Data System (ADS)

Rêgo De Vasconcelos, Bruna; Zhao, Lulu; Sharrock, Patrick; Nzihou, Ange; Pham Minh, Doan

2016-12-01

This work focused on the catalytic transformation of methane (CH4) and carbon dioxide (CO2) into syngas (mixture of CO and H2). Ruthenium- and platinum-based catalysts were prepared using hydroxyapatite (HAP) as catalyst support. Different methods for metal deposition were used including incipient wetness impregnation (IWI), excess liquid phase impregnation (LIM), and cationic exchange (CEX). Metal particle size varied in large range from less than 1 nm to dozens nm. All catalysts were active at 400-700 °C but only Pt catalyst prepared by IWI method (Pt/HAP IWI) was found stable. The catalytic performance of Pt/HAP IWI could be comparable with the literature data on noble metal-based catalysts, prepared on metal oxide supports. For the first time, water was experimentally quantified as a by-product of the reaction. This helped to correctly buckle the mass balance of the process.

Biologically Self-Assembled Memristive Circuit Elements

DTIC Science & Technology

2010-01-01

hydrothermal approach, TiO2 nanoparticles were synthesized by slowly stirring a 1:3 volumetric ratio mixture of titanium isopropoxide (TTIP) and isopropyl...Synthesis of TiO2 nanoparticles by hydrolysis and peptization of titanium isopropoxide solution. Journal of Materials Processing Technology 2007, 189...important role interfacing with group IV metal oxides such as hafnium, providing a stable linkage to the surface [3]. Titanium dioxide (TiO2), which is

Reaction of CO2 with propylene oxide and styrene oxide catalyzed by a chromium(III) amine-bis(phenolate) complex.

PubMed

Dean, Rebecca K; Devaine-Pressing, Katalin; Dawe, Louise N; Kozak, Christopher M

2013-07-07

A diamine-bis(phenolate) chromium(III) complex, {CrCl[O2NN'](BuBu)}2 catalyzes the copolymerization of propylene oxide with carbon dioxide. The synthesis of this metal complex is straightforward and it can be obtained in high yields. This catalyst incorporates a tripodal amine-bis(phenolate) ligand, which differs from the salen or salan ligands typically used with Cr and Co complexes that have been employed as catalysts for the synthesis of such polycarbonates. The catalyst reported herein yields low molecular weight polymers with narrow polydispersities when the reaction is performed at room temperature. Performing the reaction at elevated temperatures causes the selective synthesis of propylene carbonate. The copolymerization activity for propylene oxide and carbon dioxide, as well as the coupling of carbon dioxide and styrene oxide to give styrene carbonate are presented.

Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media

PubMed Central

Moret, Séverine; Dyson, Paul J.; Laurenczy, Gábor

2014-01-01

The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40 °C, 0.2 M formic acid can be obtained under 200 bar, however, in DMSO the same catalyst affords 1.9 M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes. PMID:24886955

Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media.

PubMed

Moret, Séverine; Dyson, Paul J; Laurenczy, Gábor

2014-06-02

The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40 °C, 0.2 M formic acid can be obtained under 200 bar, however, in DMSO the same catalyst affords 1.9 M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes.

First principle investigation of structural and optical properties of cubic titanium dioxide

NASA Astrophysics Data System (ADS)

Dash, Debashish; Chaudhury, Saurabh; Tripathy, Susanta K.

2018-05-01

This paper presents an analysis of structural and optical properties of cubic titanium dioxide (TiO2) using Orthogonalzed Linear Combinations of Atomic Orbitals (OLCAO) basis set under the framework of Density Functional Theory (DFT). The structural property, specially the lattice constant `a' and the optical properties such as refractive index, extinction coefficient, and reflectivity are investigated and discussed in the energy range of 0-16 eV. Further, the results have compared with previous theoretical as well as with experimental results. It was found that DFT based simulation results are approximation to experimental results.

Titanium-Dioxide Nano-Fiber-Cotton Targets for Efficient Multi-keV X-Ray Generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanabe, M; Nishimura, H; Fujioka, S

Multi-keV x-ray generation from low-density (27 {+-} 7 mg/cc) nano-fiber-cotton targets composed of titanium-dioxide has been investigated. The cotton targets were heated volumetrically and supersonically to a peak electron temperature of 2.3 keV, which is optimal to yield Ti K-shell x rays. Considerable enhancement of conversion efficiency (3.7 {+-} 0.5%) from incident laser energy into Ti K-shell x rays (4-6 keV band) was attained in comparison with that (1.4 {+-} 0.9%) for a planar Ti-foil target.

Titanium dioxide nanofiber-cotton targets for efficient multi-keV x-ray generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanabe, Minoru; Nishimura, Hiroaki; Fujioka, Shinsuke

Multi-keV x-ray generation from low-density (27{+-}7 mg/cm{sup 3}) nanofiber-cotton targets composed of titanium dioxide has been investigated. The cotton targets were heated volumetrically and supersonically to a peak electron temperature of 2.3 keV, which is optimal to yield Ti K-shell x rays. Considerable enhancement of conversion efficiency [(3.7{+-}0.5)%] from incident laser energy into Ti K-shell x rays (4-6 keV band) was attained in comparison with that [(1.4{+-}0.9)%] for a planar Ti-foil target.

Generation of highly N-type, defect passivated transition metal oxides using plasma fluorine insertion

DOEpatents

Baker, L. Robert; Seo, Hyungtak; Hervier, Antoine; Somorjai, Gabor A.

2016-04-12

A new composition of matter is disclosed wherein oxygen vacancies in a semiconducting transition metal oxide such as titanium dioxide are filled with a halogen such as Fluorine, whereby the conductivity of the composition is greatly enhanced, while at the same time the chemical stability of the composition is greatly improved. Stoichiometric titanium dioxide having less than 3 % oxygen vacancies is subject to fluorine insertion such that oxygen vacancies are filled, limited amounts of fluorine replace additional oxygen atoms and fluorine interstitially inserts into the body of the TiO.sub.2 composition.

Integrated dataset of impact of dissolved organic matter on particle behavior and phototoxicity of titanium dioxide nanoparticles

EPA Pesticide Factsheets

This dataset is generated to both qualitatively and quantitatively examine the interactions between nano-TiO2 and natural organic matter (NOM). This integrated dataset assemble all data generated in this project through a series of experiments. This dataset is associated with the following publication:Li , S., H. Ma, L. Wallis, M. Etterson , B. Riley , D. Hoff , and S. Diamond. Impact of natural organic matter on particle behavior and phototoxicity of titanium dioxide nanoparticles. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, NETHERLANDS, 542: 324-333, (2016).

Titanium dioxide in pyroclastic layers from volcanoes in the cascade range

USGS Publications Warehouse

Czamanske, G.K.; Porter, S.C.

1965-01-01

Rapid determinations of titanium dioxide have been made by x-ray emission techniques to evaluate the potentiality of using the TiO2 content of samples for checking field correlations and assisting in identification of pyroclastic units from Cascade volcanoes. Preliminary data suggest that the two most wide-spread units have characteristic ranges of TiO2 content and that other, less extensive layers have ranges which, though characteristic, often overlap the ranges of the more widespread layers. Relative to fresh samples, weathered samples from B and C soil horizons are enriched in TiO 2.

A readily prepared neutral heterobimetallic titanium(IV)-rhodium(I) catalyst for intramolecular hydroacylation.

PubMed

Morgan, John P; Kundu, Kousik; Doyle, Michael P

2005-07-14

The combination of HOCMe2CH2PPh2, Ti(OiPr)4, and [Rh(cod)Cl]2 (3:1:1) in either benzene or dichloromethane produces a discrete species (tentatively formulated as complex) that is an active catalyst for intramolecular hydroacylation reactions of 3-substituted pentenals.

Rare isotope studies involving catalytic oxidation of CO over platinum-tin oxide

NASA Technical Reports Server (NTRS)

Upchurch, Billy T.; Wood, George M., Jr.; Hess, Robert V.; Hoyt, Ronald F.

1987-01-01

Results of studies utilizing normal and rare oxygen isotopes in the catalytic oxidation of carbon monoxide over a platinum-tin oxide catalyst substrate are presented. Chemisorption of labeled carbon monoxide on the catalyst followed by thermal desorption yielded a carbon dioxide product with an oxygen-18 composition consistent with the formation of a carbonate-like intermediate in the chemisorption process. The efficacy of a method developed for the oxygen-18 labeling of the platinum-tin oxide catalyst surface for use in closed cycle pulsed care isotope carbon dioxide lasers is demonstrated for the equivalent of 10 to the 6th power pulses at 10 pulses per second.

Templated Synthesis of Aluminum Nanoparticles - A New Route to Stable Energetic Materials

DTIC Science & Technology

2009-11-05

aluminum hydride (LiAlH4), anhydrous aluminum chloride (AlCl3), titanium (IV) isopropoxide , and 1-methylpyrrolidine were supplied by Sigma-Aldrich. The...film containing the titanium salt was immersed in a tetrahydrofuran (THF) solution of 1-methylpyrrolidine alane (0.5 or 1 M) with stirring for 12 h...and a small amount of titanium from the catalyst. However, there was only a negligible amount of oxygen in the specimen despite the fact that the EDX

Structural characteristics and sorption properties of lithium-selective composite materials based on TiO2 and MnO2

NASA Astrophysics Data System (ADS)

Chaban, M. O.; Rozhdestvenska, L. M.; Palchyk, O. V.; Dzyazko, Y. S.; Dzyazko, O. G.

2018-04-01

A number of nanomaterials containing titanium dioxide and manganese dioxide were synthesized. The effect of synthesis conditions on structural and sorption characteristics for the selective extraction of lithium ions from solutions was studied. The ion-exchange materials were investigated with the methods of electron microscopy, thermogravimetric and X-ray analyses. During thermal synthesis phases of lithium manganese titanium spinel and TiO2 are being formed. Replacing a part of manganese with titanium ions leads to a decrease in the dissolution of Mn and to an increase in chemical stability. Composites with optimal values of selectivity and sorption rates were used to remove lithium ions from solutions with high salt background. The recovery degree of lithium ions under dynamic conditions reached 99%, the highest sorption capacity was found at pH 10.

Sonochemical fabrication of fluorinated mesoporous titanium dioxide microspheres

NASA Astrophysics Data System (ADS)

Yu, Changlin; Yu, Jimmy C.; Chan, Mui

2009-05-01

A sonochemical-hydrothermal method for preparing fluorinated mesoporous TiO 2 microspheres was developed. Formation of mesoporous TiO 2 and doping of fluorine was achieved by sonication and then hydrothermal treatment of a solution containing titanium isopropoxide, template, and sodium fluoride. The as-synthesized TiO 2 microspheres were characterized by X-ray diffraction (XRD), Fourier translation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, photoluminescence spectroscopy (PL), and BET surface areas. The P123 template was removed completely during the hydrothermal and washing steps, which was different from the conventional calcination treatment. The as- synthesized TiO 2 microspheres had good crystallinity and high stability. Results from the photocatalytic degradation of methylene blue (MB) showed that fluorination could remarkably improve the photocatalytic activity of titanium dioxide.

Preparation of platinum modified titanium dioxide nanoparticles with the use of laser ablation in water.

PubMed

Siuzdak, K; Sawczak, M; Klein, M; Nowaczyk, G; Jurga, S; Cenian, A

2014-08-07

We report on the preparation method of nanocrystalline titanium dioxide modified with platinum by using nanosecond laser ablation in liquid (LAL). Titania in the form of anatase crystals has been prepared in a two-stage process. Initially, irradiation by laser beam of a titanium metal plate fixed in a glass container filled with deionized water was conducted. After that, the ablation process was continued, with the use of a platinum target placed in a freshly obtained titania colloid. In this work, characterization of the obtained nanoparticles, based on spectroscopic techniques--Raman, X-ray photoelectron and UV-vis reflectance spectroscopy--is given. High resolution transmission electron microscopy was used to describe particle morphology. On the basis of photocatalytic studies we observed the rate of degradation process of methylene blue (MB) (a model organic pollution) in the presence of Pt modified titania in comparison to pure TiO2--as a reference case. Physical and chemical mechanisms of the formation of platinum modified titania are also discussed here. Stable colloidal suspensions containing Pt modified titanium dioxide crystalline anatase particles show an almost perfect spherical shape with diameters ranging from 5 to 30 nm. The TiO2 nanoparticles decorated with platinum exhibit much higher (up to 30%) photocatalytic activity towards the degradation of MB under UV illumination than pure titania.

SYNTHESIZING ALCOHOLS AND KETONES BY PHOTOINDUCED CATALYTIC PARTIAL-OXIDATION OF HYDROCARBONS IN TI02 FILM REACTORS PREPARED BY THREE DIFFERENT METHODS

EPA Science Inventory

The partial oxidation of cyclohexane to cyclohexanol and cyclohexanone on UV irradiated titanium dioxide films in the presence of molecular oxygen at ambient temperatures and pressures was studied. Three different coating methodologies (dip coating using titanium isopropoxide an...

Self-Cleaning Boudouard Reactor for Full Oxygen Recovery from Carbon Dioxide

NASA Technical Reports Server (NTRS)

Coutts, Janelle; Hintze, Paul E.; Muscatello, Anthony C.; Gibson, Tracy L.; Captain, James G.; Lunn, Griffin M.; Devor, Robert W.; Bauer, Brint; Parks, Steve

2016-01-01

Oxygen recovery from respiratory carbon dioxide is an important aspect of human spaceflight. Methods exist to sequester the carbon dioxide, but production of oxygen needs further development. The current International Space Station Carbon Dioxide Reduction System (CRS) uses the Sabatier reaction to produce water (and ultimately breathing air). Oxygen recovery is limited to 50 because half of the hydrogen used in the Sabatier reactor is lost as methane, which is vented overboard. The Bosch reaction, which converts carbon dioxide to oxygen and solid carbon is capable of recovering all the oxygen from carbon dioxide, and is the only real alternative to the Sabatier reaction. However, the last reaction in the cycle, the Boudouard reaction, produces solid carbon and the resulting carbon buildup will eventually foul the nickel or iron catalyst, reducing reactor life and increasing consumables. To minimize this fouling and increase efficiency, a number of self-cleaning catalyst designs have been created. This paper will describe recent results evaluating one of the designs.

Self-Cleaning Boudouard Reactor for Full Oxygen Recovery from Carbon Dioxide

NASA Technical Reports Server (NTRS)

Hintze, Paul E.; Muscatello, Anthony C.; Meier, Anne J.; Gibson, Tracy L.; Captain, James G.; Lunn, Griffin M.; Devor, Robert W.

2016-01-01

Oxygen recovery from respiratory carbon dioxide is an important aspect of human spaceflight. Methods exist to sequester the carbon dioxide, but production of oxygen needs further development. The current International Space Station Carbon Dioxide Reduction System (CRS) uses the Sabatier reaction to produce water (and ultimately breathing air). Oxygen recovery is limited to 50% because half of the hydrogen used in the Sabatier reactor is lost as methane, which is vented overboard. The Bosch reaction, which converts carbon dioxide to oxygen and solid carbon is capable of recovering all the oxygen from carbon dioxide, and is the only real alternative to the Sabatier reaction. However, the last reaction in the cycle, the Boudouard reaction, produces solid carbon and the resulting carbon buildup will eventually foul the nickel or iron catalyst, reducing reactor life and increasing consumables. To minimize this fouling and increase efficiency, a number of self-cleaning catalyst designs have been created. This paper will describe recent results evaluating one of the designs.

Self-Cleaning Boudouard Reactor for Full Oxygen Recovery from Carbon Dioxide

NASA Technical Reports Server (NTRS)

Hintze, Paul E.; Muscatello, Anthony C.; Gibson, Tracy L.; Captain, James G.; Lunn, Griffin M.; Devor, Robert W.; Bauer, Brint; Parks, Steve

2016-01-01

Oxygen recovery from respiratory carbon dioxide is an important aspect of human spaceflight. Methods exist to sequester the carbon dioxide, but production of oxygen needs further development. The current International Space Station Carbon Dioxide Reduction System (CRS) uses the Sabatier reaction to produce water (and ultimately breathing air). Oxygen recovery is limited to 50% because half of the hydrogen used in the Sabatier reactor is lost as methane which is vented overboard. The Bosch reaction, which converts carbon dioxide to oxygen and solid carbon, is capable of recovering all the oxygen from carbon dioxide, and it is a promising alternative to the Sabatier reaction. However, the last reaction in the cycle, the Boudouard reaction, produces solid carbon, and the resulting carbon buildup eventually fouls the catalyst, reducing reactor life and increasing consumables. To minimize this fouling and increase efficiency, a number of self-cleaning catalyst designs have been created. This paper will describe recent results evaluating one of the designs.

Advanced oxidation treatment of pulp mill effluent for TOC and toxicity removals.

PubMed

Catalkaya, Ebru Cokay; Kargi, Fikret

2008-05-01

Pulp mill effluent was treated by different advanced oxidation processes (AOPs) consisting of UV, UV/H2O2, TiO2-assisted photo-catalysis (UV/TiO2) and UV/H2O2/TiO2 in lab-scale reactors for total organic carbon (TOC) and toxicity removals. Effects of some operating parameters such as the initial pH, oxidant and catalyst concentrations on TOC and toxicity removals were investigated. Almost every method resulted in some degree of TOC and toxicity removal from the pulp mill effluent. However, the TiO2-assisted photo-catalysis (UV/TiO2) resulted in the highest TOC and toxicity removals under alkaline conditions when compared with the other AOPs tested. Approximately, 79.6% TOC and 94% toxicity removals were obtained by the TiO2-assisted photo-catalysis (UV/TiO2) with a titanium dioxide concentration of 0.75gl(-1) at pH 11 within 60min.

Hybrid bioinorganic approach to solar-to-chemical conversion.

PubMed

Nichols, Eva M; Gallagher, Joseph J; Liu, Chong; Su, Yude; Resasco, Joaquin; Yu, Yi; Sun, Yujie; Yang, Peidong; Chang, Michelle C Y; Chang, Christopher J

2015-09-15

Natural photosynthesis harnesses solar energy to convert CO2 and water to value-added chemical products for sustaining life. We present a hybrid bioinorganic approach to solar-to-chemical conversion in which sustainable electrical and/or solar input drives production of hydrogen from water splitting using biocompatible inorganic catalysts. The hydrogen is then used by living cells as a source of reducing equivalents for conversion of CO2 to the value-added chemical product methane. Using platinum or an earth-abundant substitute, α-NiS, as biocompatible hydrogen evolution reaction (HER) electrocatalysts and Methanosarcina barkeri as a biocatalyst for CO2 fixation, we demonstrate robust and efficient electrochemical CO2 to CH4 conversion at up to 86% overall Faradaic efficiency for ≥ 7 d. Introduction of indium phosphide photocathodes and titanium dioxide photoanodes affords a fully solar-driven system for methane generation from water and CO2, establishing that compatible inorganic and biological components can synergistically couple light-harvesting and catalytic functions for solar-to-chemical conversion.

Marine environmental protection: An application of the nanometer photo catalyst method on decomposition of benzene.

PubMed

Lin, Mu-Chien; Kao, Jui-Chung

2016-04-15

Bioremediation is currently extensively employed in the elimination of coastal oil pollution, but it is not very effective as the process takes several months to degrade oil. Among the components of oil, benzene degradation is difficult due to its stable characteristics. This paper describes an experimental study on the decomposition of benzene by titanium dioxide (TiO2) nanometer photocatalysis. The photocatalyst is illuminated with 360-nm ultraviolet light for generation of peroxide ions. This results in complete decomposition of benzene, thus yielding CO2 and H2O. In this study, a nonwoven fabric is coated with the photocatalyst and benzene. Using the Double-Shot Py-GC system on the residual component, complete decomposition of the benzene was verified by 4h of exposure to ultraviolet light. The method proposed in this study can be directly applied to elimination of marine oil pollution. Further studies will be conducted on coastal oil pollution in situ. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hybrid bioinorganic approach to solar-to-chemical conversion

PubMed Central

Nichols, Eva M.; Gallagher, Joseph J.; Liu, Chong; Su, Yude; Resasco, Joaquin; Yu, Yi; Sun, Yujie; Yang, Peidong; Chang, Michelle C. Y.; Chang, Christopher J.

2015-01-01

Natural photosynthesis harnesses solar energy to convert CO2 and water to value-added chemical products for sustaining life. We present a hybrid bioinorganic approach to solar-to-chemical conversion in which sustainable electrical and/or solar input drives production of hydrogen from water splitting using biocompatible inorganic catalysts. The hydrogen is then used by living cells as a source of reducing equivalents for conversion of CO2 to the value-added chemical product methane. Using platinum or an earth-abundant substitute, α-NiS, as biocompatible hydrogen evolution reaction (HER) electrocatalysts and Methanosarcina barkeri as a biocatalyst for CO2 fixation, we demonstrate robust and efficient electrochemical CO2 to CH4 conversion at up to 86% overall Faradaic efficiency for ≥7 d. Introduction of indium phosphide photocathodes and titanium dioxide photoanodes affords a fully solar-driven system for methane generation from water and CO2, establishing that compatible inorganic and biological components can synergistically couple light-harvesting and catalytic functions for solar-to-chemical conversion. PMID:26305947

Photoelectrocatalytic Synthesis of Hydrogen Peroxide by Molecular Copper-Porphyrin Supported on Titanium Dioxide Nanotubes.

PubMed

Apaydin, Dogukan H; Seelajaroen, Hathaichanok; Pengsakul, Orathip; Thamyongkit, Patchanita; Sariciftci, Niyazi Serdar; Kunze-Liebhäuser, Julia; Portenkirchner, Engelbert

2018-04-24

We report on a self-assembled system comprising a molecular copper-porphyrin photoelectrocatalyst, 5-(4-carboxy-phenyl)-10,15,20-triphenylporphyrinatocopper(II) (CuTPP-COOH), covalently bound to self-organized, anodic titania nanotube arrays (TiO 2 NTs) for photoelectrochemical reduction of oxygen. Visible light irradiation of the porphyrin-covered TiO 2 NTs under cathodic polarization up to -0.3 V vs. Normal hydrogen electrode (NHE) photocatalytically produces H 2 O 2 in pH neutral electrolyte, at room temperature and without need of sacrificial electron donors. The formation of H 2 O 2 upon irradiation is proven and quantified by direct colorimetric detection using 4-nitrophenyl boronic acid ( p -NPBA) as a reactant. This simple approach for the attachment of a small molecular catalyst to TiO 2 NTs may ultimately allow for the preparation of a low-cost H 2 O 2 evolving cathode for efficient photoelectrochemical energy storage under ambient conditions.

Chemical dynamics of the first proton-coupled electron transfer of water oxidation on TiO2 anatase.

PubMed

Chen, Jia; Li, Ye-Fei; Sit, Patrick; Selloni, Annabella

2013-12-18

Titanium dioxide (TiO2) is a prototype, water-splitting (photo)catalyst, but its performance is limited by the large overpotential for the oxygen evolution reaction (OER). We report here a first-principles density functional theory study of the chemical dynamics of the first proton-coupled electron transfer (PCET), which is considered responsible for the large OER overpotential on TiO2. We use a periodic model of the TiO2/water interface that includes a slab of anatase TiO2 and explicit water molecules, sample the solvent configurations by first principles molecular dynamics, and determine the energy profiles of the two electronic states involved in the electron transfer (ET) by hybrid functional calculations. Our results suggest that the first PCET is sequential, with the ET following the proton transfer. The ET occurs via an inner sphere process, which is facilitated by a state in which one electronic hole is shared by the two oxygen ions involved in the transfer.

Laser-induced amorphization of silicon during pulsed-laser irradiation of TiN/Ti/polycrystalline silicon/SiO2/silicon

NASA Astrophysics Data System (ADS)

Chong, Y. F.; Pey, K. L.; Wee, A. T. S.; Thompson, M. O.; Tung, C. H.; See, A.

2002-11-01

In this letter, we report on the complex solidification structures formed during laser irradiation of a titanium nitride/titanium/polycrystalline silicon/silicon dioxide/silicon film stack. Due to enhanced optical coupling, the titanium nitride/titanium capping layer increases the melt depth of polycrystalline silicon by more than a factor of 2. It is found that the titanium atoms diffuse through the entire polycrystalline silicon layer during irradiation. Contrary to the expected polycrystalline silicon growth, distinct regions of polycrystalline and amorphous silicon are formed instead. Possible mechanisms for the formation of these microstructures are proposed.

The Genotoxicity of Titanium Dioxide and Cerium Dioxide Nanoparticles in Human Respiratory Epithelial Cells

EPA Science Inventory

Due to the exponential growth of the nanomaterial industry, risk assessment of human exposure to nanomaterials in consumer products is of paramount importance. The genotoxicity of nanomaterials is an important aspect of hazard identification and regulatory guidance. However, this...

Genotoxic Effects of Titanium Dioxide and Cerium Dioxide Nanoparticles in Human Respiratory Epithelial Cells

EPA Science Inventory

The nanomaterial industry has recently seen rapid growth, therefore, the risk assessment of human exposure to nanomaterials in consumer products is of paramount importance. The genotoxicity of nanomaterials is a fundamental aspect of hazard identification and regulatory guidance....

Pre-post evaluation of effects of a titanium dioxide coating on environmental contamination of an intensive care unit: the TITANIC study.

PubMed

de Jong, B; Meeder, A M; Koekkoek, K W A C; Schouten, M A; Westers, P; van Zanten, A R H

2018-07-01

Among patients admitted to European hospitals or intensive care units (ICUs), 5.7% and 19.5% will encounter healthcare-associated infections (HAIs), respectively, and antimicrobial resistance is emerging. As hospital surfaces are contaminated with potentially pathogenic bacteria, environmental cleanliness is an essential aspect to reduce HAIs. To address the efficacy of a titanium dioxide coating in reducing the microbial colonization of environmental surfaces in an ICU. A prospective, controlled, single-centre pilot study was conducted to examine the effect of a titanium dioxide coating on the microbial colonization of surfaces in an ICU. During the pre- and post-intervention periods, surfaces were cultured with agar contact plates (BBL RODAC plates). Factors that were potentially influencing the bacterial colonization of surfaces were recorded. A repeated measurements analysis within a hierarchic multi-level framework was used to analyse the effect of the intervention, controlling for the explanatory variables. The mean ratio for the total number of colony-forming units (cfus) in a room between the pre- and post-intervention periods was 0.86 (standard deviation 0.57). The optimal model included the following explanatory variables: intervention (P=0.065), week (P=0.002), culture surfaces (P<0.001), ICU room (P=0.039), and interaction between intervention and week (P=0.002) and between week and culture surfaces (P=0.031). The effect of the intervention on the number of cfus from all culture plates in Week 4 between the pre- and post-intervention periods was -0.47 (95% confidence interval -0.24 to - 0.70). This study found that a titanium dioxide coating had no effect on the microbial colonization of surfaces in an ICU. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Three-dimensionally ordered macroporous (3DOM) gold-nanoparticle-doped titanium dioxide (GTD) photonic crystals modified electrodes for hydrogen peroxide biosensor.

PubMed

Li, Jianlin; Han, Tao; Wei, Nannan; Du, Jiangyan; Zhao, Xiangwei

2009-12-15

Gold nanoparticles have been introduced into the wall framework of titanium dioxide photonic crystals by the colloidal crystal template technique. The three-dimensionally ordered macroporous gold-nanoparticle-doped titanium dioxide (3DOM GTD) film was modified on the indium-tin oxide (ITO) electrode surface and used for the hydrogen peroxide biosensor. The direct electron transfer and electrocatalysis of horseradish peroxidase (HRP) immobilized on this film have been investigated. The 3DOM GTD film could provide a good microenvironment for retaining the biological bioactivity, large internal area, and superior conductivity. The HRP/3DOM GTD/ITO electrode exhibited two couples of redox peaks corresponding to the HRP intercalated in the mesopores and adsorbed on the external surface of the film with the formal potential of -0.19 and -0.52V in 0.1M PBS (pH 7.4), respectively. The HRP intercalated in the mesopores showed a surface-controlled process with a single proton transfer. The direct electron transfer between the adsorbed HRP and the electrode is achieved without the aid of an electron mediator. The H(2)O(2) biosensor displayed a rapid eletrocatalytic response (less than 3s), a wide linear range from 0.5 microM to 1.4mM with a detection limit of 0.2 microM, high sensitivity (179.9 microAmM(-1)), good stability and reproducibility. Compared with the free-Au doped titanium dioxide photonic crystals modified electrode, the GTD modified electrode could greatly enhance the response current signal, linear detection range and higher sensitivity. The 3DOM GTD provided a new matrix for protein immobilization and direct transfer study and opened a way for low conductivity electrode biosensor.

Bosch Reactor Development for High Percentage Oxygen Recovery from Carbon Dioxide

NASA Technical Reports Server (NTRS)

Howard, David; Abney, Morgan

2015-01-01

This next Generation Life Support Project entails the development and demonstration of Bosch reaction technologies to improve oxygen recovery from metabolically generated oxygen and/or space environments. A primary focus was placed on alternate carbon formation reactor concepts to improve useful catalyst life for space vehicle applications, and make use of in situ catalyst resources for non-terrestrial surface missions. Current state-of-the-art oxygen recovery systems onboard the International Space Station are able to effectively recover approximately 45 percent of the oxygen consumed by humans and exhausted in the form of carbon dioxide (CO2). Excess CO2 is vented overboard and the oxygen contained in the molecules is lost. For long-duration missions beyond the reaches of Earth for resupply, it will be necessary to recover greater amounts of constituents such as oxygen that are necessary for sustaining life. Bosch technologies theoretically recover 100 percent of the oxygen from CO2, producing pure carbon as the sole waste product. Challenges with this technology revolve around the carbon product fouling catalyst materials, drastically limiting catalyst life. This project successfully demonstrated techniques to extend catalyst surface area exposure times to improve catalyst life for vehicle applications, and demonstrated the use of Martian and lunar regolith as viable catalyst Bosch Reactor Development for High Percentage Oxygen Recovery From Carbon Dioxide materials for surface missions. The Bosch process generates carbon nanotube formation within the regolith, which has been shown to improve mechanical properties of building materials. Production of bricks from post reaction regolith for building and radiation shielding applications were also explored.

Oxygen reduction reaction (ORR) on mixed oxy-nitride non-noble catalyst: Ab-initio simulation, elaboration and characterization

NASA Astrophysics Data System (ADS)

Seifitokaldani, Ali

In this project, titanium oxy-nitride (TiOxN y) has been studied as a new non-noble electrocatalyst for the oxygen reduction reaction (ORR). A comprehensive comparison between four different sol-gel methods was carried out to evaluate the physicochemical and electrochemical properties of the produced electro-catalysts. Among them, a new urea-based sol-gel method (simply called U method) is introduced to prepare TiOxNy at a fairly low temperature and duration, with higher electro-catalytic activity for the ORR. The prepared electro-catalysts with different N/O ratios showed different properties from a less conductive behavior in oxygen-rich (low N/O ratio) materials to more conductive electro-catalyst behavior in nitrogen-rich (high N/O ratio) oxy-nitrides, respectively. Generally, electro-catalysts prepared by the U method had more titanium nitride in their structures than the electro-catalysts prepared by the other methods. Nevertheless, heat treatment had a key role in this phase transferring from having high oxide structure to high nitride structure. According to the elemental analysis done by energy dispersive spectroscopy (EDS), nitrogen percentage in the bulk material increased from 9 to 24 percent by increasing the temperature from 700 to 1100 °C, while the oxygen percentage was decreasing inversely. In addition, based on the X-ray diffraction (XRD) data, in the case of U method, the TiN characteristic peaks were obvious, even at lower temperatures. Increasing the temperature also made the peaks much sharper indicating the growth of the crystallite size. The calculated crystallite size showed the crystallite size of samples prepared by U method (20 to 40 nm) was almost in the same range of the TiN crystallite size, but the crystallite size of the samples prepared by the other sol-gel methods (40 to 60 nm) was in the same range of the TiO2 crystallite size. Scanning electron microscopy (SEM) and B.E.T. surface area analyzer were used to evaluate the particle size and surface area of different samples, respectively. They indicated a smaller particle size and a higher surface area in the electro-catalysts produced by the U method. Besides the aforementioned physicochemical characterizations, cyclic voltammetry (CV), polarization, and electrochemical impedance spectroscopy (EIS) were used to evaluate the electrochemical properties of the electro-catalysts. Obtained Tafel slope, exchange current density and onset potential revealed that the electro-catalyst prepared by the U method which was annealed at 1100 °C, had the best electro-catalytic activity among all other samples with Tafel slope of -203 mV/decade, exchange current density around 4E-04 mA/mg and the onset potential close to 0.8 volt vs. NHE (normal hydrogen electrode). EIS measurements also supported this assertion through revealing the highest specific capacitance (˜ 3.3 F/g). This result was in agreement with the highest B.E.T. surface area and the lowest charge transfer resistance exhibited by this electro-catalyst among the other samples. Stability is one of the determinant factors in selecting an electro-catalyst for the ORR. In this regard, ICP-TOF-MS was used to evaluate the chemical stability of the prepared electro-catalysts under corrosive acidic environment, by measuring the concentration of the dissolved titanium after a certain time. Heretofore, measuring the dissolved metal concentration by ICP-TOF-MS was done just to evaluate its chemical stability. However, in this project this technique was also used during the CV, to evaluate the electro-catalyst's electrochemical stability as well, which is more realistic and similar to the PEMFC's working condition. Stability of the best electrocatalyst with the highest catalytic activity (prepared by the U method) was better than the commercially used Pt/C electro-catalyst, both chemically and electrochemically. Electrochemical stability of the prepared electro-catalysts has also been studied at a high oxidizing potential (more than 2 volts vs. NHE). X-ray Photoelectron Spectroscopy (XPS) showed that the nitrogen amount on the surface of the electro-catalyst decreased from 11 % before the oxidation to 5 % after the oxidation, whereas the catalytic activity for the ORR decreased after the oxidation. Thus, decreasing the titanium nitride's amount in the titanium oxy-nitride surface reduced its catalytic activity. In the second phase of this project, electro-catalytic activity of the titanium nitride for the ORR was investigated via a density functional theory (DFT) computation. To the best of our knowledge, there is no theoretical and computational quantum chemistry study of the transition metal's nitride as the electro-catalyst in PEM fuel cells. ORR was considered to take place in three different sequential steps namely oxygen adsorption, hydroxide production and water desorption. Based on the XRD results, TiN(111) and TiN(200) were considered as the two major facets of the TiN. Simulation was done by the Vienna ab initio Simulation Package (VASP) based on the Plane-Wave basis sets and periodic boundary condition, while the PBE exchangecorrelational functional was used to describe the interactions among electrons. Comparing the adsorption energies proved existence of a strong dissociative adsorption of oxygen on the TiN(111) regardless of the adsorption sites. However, because of a relatively strong OH adsorption, TiN(111) loses the active sites to proceed the ORR, while on the TiN(200) surface, water production and desorption came about easily. Electron density of states (DOS) was obtained to calculate the d-band center and fractional filling in different situations. Considering two possible bridge and top adsorption sites on the TiN(200), these information indicated the hydroxide production and water desorption as the rate determining steps for the ORR in bridge and top sites, respectively. Therefore, it was shown that the TiN, specially TiN(200) had exhibited good electro-catalytic activity for the ORR. Losing this TiN amount from the titanium oxy-nitride's surface might be responsible for the decrease of the electro-catalytic activity of the titanium oxy-nitride for the ORR.

Electrophilic activation of alkynes for enyne cycloisomerization reactions with in situ generated early/late heterobimetallic Pt-Ti catalysts.

PubMed

Talley, Michael R; Stokes, Ryjul W; Walker, Whitney K; Michaelis, David J

2016-06-14

In situ formation of heterobimetallic Pt-Ti catalysts enables rapid room temperature catalysis in enyne cycloisomerization reactions. The Lewis acidic titanium atom in the ligand framework is shown to be essential for fast catalysis. A range of enyne substrates are efficiently cyclized to carbocycles and heterocycles in high yield.

The effect of titanium nickel nitride decorated carbon nanotubes-reduced graphene oxide hybrid support for methanol oxidation

NASA Astrophysics Data System (ADS)

Liu, Gen; Pan, Zhanchang; Li, Wuyi; Yu, Ke; Xia, Guowei; Zhao, Qixiang; Shi, Shikun; Hu, Guanghui; Xiao, Chumin; Wei, Zhigang

2017-07-01

Titanium nickel nitride (TiNiN) decorated three-dimensional (3D) carbon nanotubes-reduced graphene oxide (CNT-rGO), a fancy 3D platinum (Pt)-based catalyst hybrid support, is prepared by a solvothermal process followed by a nitriding process, which is tested as anodic catalyst support for the methanol oxidation reaction (MOR). The structure, morphology and composition of the synthesized TiNiN/CNT-rGO exhibits a uniform particle dispersion with high purity and interpenetrating 3D network structure. Notably, Pt/TiNiN/CNT-rGO catalyst exhibits significantly improved catalytic activity and durability for methanol oxidation in comparison with Pt/CNT-rGO and conventional Pt/C (JM). The outstanding electrochemical performance was attributed to structure and properties. That is, the 3D CNT-rGO provided a fast transport network for charge-transfer and mass-transfer as well as TiNiN NPs with good synergistic effect and the strong electronic coupling between different domains in TiNiN/CNT-rGO, thus the catalytic activity of the novel catalyst is greatly improved. These results evidences 3D TiNiN/CNT-rGO as a promising catalyst support for a wide range of applications in fuel cells.

Sustainable production of green feed from carbon dioxide and hydrogen.

PubMed

Landau, Miron V; Vidruk, Roxana; Herskowitz, Moti

2014-03-01

Carbon dioxide hydrogenation to form hydrocarbons was conducted on two iron-based catalysts, prepared according to procedures described in the literature, and on a new iron spinel catalyst. The CO2 conversion measured in a packed-bed reactor was limited to about 60% because of excessive amounts of water produced in this process. Switching to a system of three packed-bed reactors in series with interim removal of water and condensed hydrocarbons increased CO2 conversion to as much as 89%. The pure spinel catalyst displayed a significantly higher activity and selectivity than those of the other iron catalysts. This process produces a product called green feed, which is similar in composition to the product of a high-temperature, iron-based Fischer–Tropsch process from syngas. The green feed can be readily converted into renewable fuels by well-established technologies.

Continuous wasteless ecologically safe technology of propylenecarbonate production in presence of phthalocyanine catalysts

DOEpatents

Afanasiev, Vladimir Vasilievich [Moscow, RU; Zefirov, Nikolai Serafimovich [Moscow, RU; Zalepugin, Dmitry Yurievich [Moscow, RU; Polyakov, Victor Stanislavovich [Moscow, RU; Tilkunova, Nataliya Alexandrovna [Moscow, RU; Tomilova, Larisa Godvigovna [Moscow, RU

2009-09-08

A continuous method of producing propylenecarbonate includes carboxylation of propylene oxide with carbon dioxide in presence of phthalocyanine catalyst on an inert carrier, using as the phthalocyanine catalyst at least one catalyst selected from the group consisting of not-substituted, methyl, ethyl, butyl, and tret butyl-substituted phthalocyanines of metals, including those containing counterions, and using as the carrier a hydrophobic carrier.

Shifting from Ziegler-Natta to Philips-type catalyst? A simple and safe access to reduced titanium systems for ethylene polymerization.

PubMed

Popoff, Nicolas; Espinas, Jeff; Gouré, Eric; Boyron, Olivier; Le Roux, Erwan; Basset, Jean-Marie; Gauvin, Régis M; De Mallmann, Aimery; Taoufik, Mostafa

2011-12-01

Silica-supported titanium(IV) chloride is readily reduced by Mashima and co-workers' reagent (1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene) to afford materials active in ethylene polymerisation without need of aluminum alkyl cocatalyst. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

PubMed Central

Agócs, Tamás Zoltán; Puskás, István; Varga, Erzsébet; Molnár, Mónika

2016-01-01

Advanced oxidation processes (AOPs) are considered highly competitive water treatment technologies for the removal of organic pollutants. Among AOP techniques, photocatalysis has recently been the most widely studied. Our aims were to investigate how the dispersion of nanosized titanium dioxide (nanoTiO2) applied in photodegradation-based procedures can be stabilized with cyclodextrins in order to obtain a new, more efficient photocatalyst for the purification of waters polluted by xenobiotics applying UV irradiation. During our work, on the one hand, we studied the behavior and stability of nanoTiO2 in cyclodextrin solutions. On the other hand, we used various monomer and polymer cyclodextrin derivatives, and assessed the options for nanoTiO2 stabilization in the presence of various salts and tap water on the basis of turbidity tests. The physical stability of nanoTiO2 dispersions is diminished in the presence of the salts found in tap water (and occurring also in surface waters and ground water) and they are precipitated immediately. This colloidal instability can be improved by cyclodextrin derivatives. Based on the results of our studies we have selected carboxymethyl β-cyclodextrin polymer (CMBCD-P) for stabilization of nanoTiO2 dispersions. The photocatalytic degradation of methylene blue and ibuprofen as model organic pollutants in various media (distilled water, NaCl solution and tap water) has been studied using nanoTiO2 as catalyst stabilized by CMBCD-P. CMBCD-P itself showed a catalytic effect on the UV degradation of methylene blue. In addition to enhancing the colloid stability of nanoTiO2 CMBCD-P showed also synergistic effects in catalyzing the photodecomposition process of the dye. On the other hand, ibuprofen as a model pharmaceutical, a pollutant of emerging concern (EP), was protected by CMBCD-P against the photocatalytic degradation showing that inclusion complex formation can result in opposite effects depending on the structure of the host–guest complex. PMID:28144360

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants.

PubMed

Agócs, Tamás Zoltán; Puskás, István; Varga, Erzsébet; Molnár, Mónika; Fenyvesi, Éva

2016-01-01

Advanced oxidation processes (AOPs) are considered highly competitive water treatment technologies for the removal of organic pollutants. Among AOP techniques, photocatalysis has recently been the most widely studied. Our aims were to investigate how the dispersion of nanosized titanium dioxide (nanoTiO 2 ) applied in photodegradation-based procedures can be stabilized with cyclodextrins in order to obtain a new, more efficient photocatalyst for the purification of waters polluted by xenobiotics applying UV irradiation. During our work, on the one hand, we studied the behavior and stability of nanoTiO 2 in cyclodextrin solutions. On the other hand, we used various monomer and polymer cyclodextrin derivatives, and assessed the options for nanoTiO 2 stabilization in the presence of various salts and tap water on the basis of turbidity tests. The physical stability of nanoTiO 2 dispersions is diminished in the presence of the salts found in tap water (and occurring also in surface waters and ground water) and they are precipitated immediately. This colloidal instability can be improved by cyclodextrin derivatives. Based on the results of our studies we have selected carboxymethyl β-cyclodextrin polymer (CMBCD-P) for stabilization of nanoTiO 2 dispersions. The photocatalytic degradation of methylene blue and ibuprofen as model organic pollutants in various media (distilled water, NaCl solution and tap water) has been studied using nanoTiO 2 as catalyst stabilized by CMBCD-P. CMBCD-P itself showed a catalytic effect on the UV degradation of methylene blue. In addition to enhancing the colloid stability of nanoTiO 2 CMBCD-P showed also synergistic effects in catalyzing the photodecomposition process of the dye. On the other hand, ibuprofen as a model pharmaceutical, a pollutant of emerging concern (EP), was protected by CMBCD-P against the photocatalytic degradation showing that inclusion complex formation can result in opposite effects depending on the structure of the host-guest complex.

Titanium Dioxide Coating Prepared by Use of a Suspension-Solution Plasma-Spray Process

NASA Astrophysics Data System (ADS)

Du, Lingzhong; Coyle, Thomas W.; Chien, Ken; Pershin, Larry; Li, Tiegang; Golozar, Mehdi

2015-08-01

Titanium dioxide coatings were prepared from titanium isopropoxide solution containing nano TiO2 particles by use of a plasma-spray process. The effects of stand-off distance on coating composition and microstructure were investigated and compared with those for pure solution precursor and a water-based suspension of TiO2. The results showed that the anatase content of the coating increased with increasing stand-off distance and the rate of deposition decreased with increasing spray distance. Anatase nanoparticles in solution were incorporated into the coatings without phase transformation whereas most of the TiO2 in the precursor solution was transformed into rutile. The microstructure of preserved anatase particles bound by rutile improved the efficiency of deposition of the coating. The amount of anatase phase can be adjusted by variation of the ratio of solution to added anatase TiO2 nanoparticles.

Synthesis of nano-titanium dioxide by sol-gel route

NASA Astrophysics Data System (ADS)

Kaler, Vandana; Duchaniya, R. K.; Pandel, U.

2016-04-01

Nanosized titanium dioxide powder was synthesised via sol-gel route by hydrolysis of titanium tetraisopropoxide with ethanol and water mixture in high acidic medium. The synthesized nanopowder was further characterized by X-ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and Ultraviolet Visible Spectroscopy in order to determine size, morphology and crystalline structure of the material. The synthesis of nano-TiO2 powder in anatase phase was realized by XRD. The optical studies of nano-TiO2 powder was carried out by UV-Vis spectroscopy and band gap was calculated as 3.5eV, The SEM results with EDAX confirmed that prepared nano-TiO2 particles were in nanometer range with irregular morphology. The FTIR analysis showed that only desired functional groups were present in sample. These nano-TiO2 particles have applications in solar cells, chemical sensors and paints, which are thrust areas these days.

Titanium Dioxide Volatility in High Temperature Water Vapor

NASA Technical Reports Server (NTRS)

Nguyen, QynhGiao N.

2008-01-01

Titanium (Ti) containing materials are of high interest to the aerospace industry due to its high temperature capability, strength, and light weight. As with most metals an exterior oxide layer naturally exists in environments that contain oxygen (i.e. air). At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study will evaluate cold pressed titanium dioxide (TiO2) powder pellets at a temperature range of 1400 C - 1200 C in water containing environments to determine the volatile hydroxyl species using the transpiration method. The water content ranged from 0-76 mole% and the oxygen content range was 0-100 mole % during the 20-250 hour exposure times. Preliminary results indicate that oxygen is not a key contributor at these temperatures and the following reaction is the primary volatile equation for all three temperatures: TiO2 (s) + H2O (g) = TiO(OH)2 (g).

Fischer-Tropsch process

DOEpatents

Dyer, Paul N.; Pierantozzi, Ronald; Withers, Howard P.

1987-01-01

A Fischer-Tropsch process utilizing a product selective and stable catalyst by which synthesis gas, particularly carbon-monoxide rich synthesis gas is selectively converted to higher hydrocarbons of relatively narrow carbon number range is disclosed. In general, the selective and notably stable catalyst, consist of an inert carrier first treated with a Group IV B metal compound (such as zirconium or titanium), preferably an alkoxide compound, and subsequently treated with an organic compound of a Fischer-Tropsch metal catalyst, such as cobalt, iron or ruthenium carbonyl. Reactions with air and water and calcination are specifically avoided in the catalyst preparation procedure.

Titanium dioxide antireflection coating for silicon solar cells by spray deposition

NASA Technical Reports Server (NTRS)

Kern, W.; Tracy, E.

1980-01-01

A high-speed production process is described for depositing a single-layer, quarter-wavelength thick antireflection coating of titanium dioxide on metal-patterned single-crystal silicon solar cells for terrestrial applications. Controlled atomization spraying of an organotitanium solution was selected as the most cost-effective method of film deposition using commercial automated equipment. The optimal composition consists of titanium isopropoxide as the titanium source, n-butyl acetate as the diluent solvent, sec-butanol as the leveling agent, and 2-ethyl-1-hexanol to render the material uniformly depositable. Application of the process to the coating of circular, large-diameter solar cells with either screen-printed silver metallization or with vacuum-evaporated Ti/Pd/Ag metallization showed increases of over 40% in the electrical conversion efficiency. Optical characteristics, corrosion resistance, and several other important properties of the spray-deposited film are reported. Experimental evidence indicates a wide tolerance in the coating thickness upon the overall efficiency of the cell. Considerations pertaining to the optimization of AR coatings in general are discussed, and a comprehensive critical survey of the literature is presented.

Rapid sonosynthesis of N-doped nano TiO2 on wool fabric at low temperature: introducing self-cleaning, hydrophilicity, antibacterial/antifungal properties with low alkali solubility, yellowness and cytotoxicity.

PubMed

Behzadnia, Amir; Montazer, Majid; Rashidi, Abousaeid; Mahmoudi Rad, Mahnaz

2014-01-01

Nano nitrogen-doped titanium dioxide was rapidly prepared by hydrolysis of titanium isopropoxide at 75-80°C using in situ sonochemical synthesis by introducing ammonia. Various concentrations of titanium isopropoxide were examined to deposit nano nitrogen-doped titanium dioxide through impregnation of the wool fabric in ultrasound bath followed by curing. The antibacterial/antifungal activities of wool samples were assessed against two common pathogenic bacteria including Escherichia coli and Staphylococcus aureus and the diploid fungus Candida albicans. The sonotreated wool fabrics indicated no adverse effects on human dermal fibroblasts. The presence of nanoparticles on the sonotreated wool fabrics were confirmed by FE-SEM images and EDS patterns and X-ray mapping and the crystalline size of nanoparticles were estimated through XRD results. The role of both pH and precursor concentration on the various properties of the fabric was investigated and the optimized conditions introduced using response surface methodology. © 2014 The American Society of Photobiology.

Investigation of the Effects of MIR-FELIrradiation on the Photoluminescence of Titanium Dioxides

NASA Astrophysics Data System (ADS)

Sonobe, T.; Bakr, M.; Yoshida, K.; Higashimura, K.; Kinjo, R.; Hachiya, K.; Kii, T.; Masuda, K.; Ohgaki, H.

2010-02-01

A mid-infrared free electron laser (MIR-FEL: 5 μm-20 μm) facility (KU-FEL: Kyoto University Free Electron Laser) has been constructed in Institute of Advanced Energy Kyoto University, and first laser saturation at 13.2 μm was achieved in May 2008. Currently, we have started to develop the application of MIR-FEL in the field of energy and material science. This study aimed at investigating the feasibility for the development of new evaluation technique of electron-phonon interaction in metal oxides by MIR-FEL. A preliminary result of electrical and optical properties of titanium dioxides was presented.

Dynamic quenching study of 2-amino-3-bromo-1,4-naphthoquinone by titanium dioxide nano particles in solution (methanol).

PubMed

Pushpam, S; Kottaisamy, M; Ramakrishnan, V

2013-10-01

The dependence of fluorescence emission of 2-amino-3-bromo-1,4-naphthoquinone on titanium dioxide (TiO2) in methanol has been investigated. The increase in TiO2 concentration causes a decrease in the fluorescence intensity of 2-amino-3-bromo-1,4-naphthoquinone. A linear Stern-Volmer plot in this study indicates the presence of dynamic quenching. The quenching and association constants have been calculated. The quenching process is due to the electron transfer from 2-amino-3-bromo-1,4-naphthoquinone to TiO2. Copyright © 2013 Elsevier B.V. All rights reserved.

Far-ultraviolet spectral changes of titanium dioxide with gold nanoparticles by ultraviolet and visible light

NASA Astrophysics Data System (ADS)

Tanabe, Ichiro; Kurawaki, Yuji

2018-05-01

Attenuated total reflectance spectra including the far-ultraviolet (FUV, ≤ 200 nm) region of titanium dioxide (TiO2) with and without gold (Au) nanoparticles were measured. A newly developed external light-irradiation system enabled to observe spectral changes of TiO2 with Au nanoparticles upon light irradiations. Absorption in the FUV region decreased and increased by the irradiation with ultraviolet and visible light, respectively. These spectral changes may reflect photo-induced electron transfer from TiO2 to Au nanoparticles under ultraviolet light and from Au nanoparticles to TiO2 under visible light, respectively.

Perovskite solar cells in N-I-P structure with four slot-die-coated layers

PubMed Central

Burkitt, Daniel; Searle, Justin

2018-01-01

The fabrication of perovskite solar cells in an N-I-P structure with compact titanium dioxide blocking, mesoporous titanium dioxide scaffold, single-step perovskite and hole-transport layers deposited using the slot-die coating technique is reported. Devices on fluorine-doped tin oxide-coated glass substrates with evaporated gold top contacts and four slot-die-coated layers are demonstrated, and best cells reach stabilized power conversion efficiencies of 7%. This work demonstrates the suitability of slot-die coating for the production of layers within this perovskite solar cell stack and the potential to transfer to large area and roll-to-roll manufacturing processes. PMID:29892402

Integrated titanium dioxide (TiO2) nanoparticles on interdigitated device electrodes (IDEs) for pH analysis

NASA Astrophysics Data System (ADS)

Azizah, N.; Hashim, U.; Arshad, M. K. Md.; Gopinath, Subash C. B.; Nadzirah, Sh.; Farehanim, M. A.; Fatin, M. F.; Ruslinda, A. R.; Ayub, R. M.

2016-07-01

Titanium dioxide (TiO2) nanoparticles based Interdigitated Device Electrodes (IDEs) Nanobiosensor device was developed for intracellular biochemical detection. Fabrication and characterization of pH sensors using IDE nanocoated with TiO2 was studied in this paper. In this paper, a preliminary assessment of this intracellular sensor with electrical measurement under different pH levels. 3-aminopropyltriethoxysilane (APTES) was used to enhance the sensitivity of titanium dioxide layer as well as able to provide surface modification by undergoing protonation and deprotonation process. Different types of pH solution provide different resistivity and conductivity towards the surface. Base solution has the higher current compared to an acid solution. Amine and oxide functionalized TiO2 based IDE exhibit pH-dependent could be understood in terms of the change in surface charge during protonation and deprotonation. The simple fabrication process, high sensitivity, and fast response of the TiO2 based IDEs facilitate their applications in a wide range of areas. The small size of semiconductor TiO2 based IDE for sensitive, label-free, real time detection of a wide range of biological species could be explored in vivo diagnostics and array-based screening.

Molecular and physiological responses to titanium dioxide ...

EPA Pesticide Factsheets

- Changes in tissue transcriptomes and productivity of Arabidopsis thaliana were investigated during exposure of plants to two widely-used engineered metal oxide nanoparticles, titanium dioxide (nano-titanium) and cerium dioxide (nano-cerium). Microarray analyses confirmed that exposure to either nanoparticle altered the transcriptomes of rosette leaves and roots, with comparatively larger numbers of differentially expressed genes (DEGs) found under nano-titania exposure. Nano-titania induced more DEGs in rosette leaves, whereas roots had more DEGs under nano-ceria exposure. MapMan analyses indicated that while nano-titania up-regulated overall and secondary metabolism in both tissues, metabolic processes under nano-ceria remained mostly unchanged. Gene enrichment analysis indicated that both nanoparticles mainly enriched ontology groups such as responses to stress (abiotic and biotic), and defense responses (pathogens), and responses to endogenous stimuli (hormones). Nano-titania specifically induced genes associated with photosynthesis, whereas nano-ceria induced expression of genes related to activating transcription factors, most notably those belonging to the ethylene responsive element binding protein family. Interestingly, there were also increased numbers of rosette leaves and plant biomass under nano-ceria exposure, but not under nano-titania. Other transcriptomic responses did not clearly relate to responses observed at the organism level. This may b

Nanoparticle–Cell Interactions: Relevance for Public Health

PubMed Central

2017-01-01

Nanoparticles, especially metal oxide nanoparticles, are used in a wide range of commercial and industrial applications that result in direct human contact, such as titanium dioxide nanoparticles in paints, food colorings, and cosmetics, or indirectly through release of nanoparticle-containing materials into the environment. Workers who process nanoparticles for downstream applications are exposed to especially high concentrations of nanoparticles. For physical chemists, nanoparticles present an interesting area of study as the small size of nanoparticles changes the properties from that of the bulk material, leading to novel properties and reactivity. For the public health community, this reduction in particle size means that exposure limits and outcomes that were determined from bulk material properties are not necessarily valid. Informed determination of exposure limits requires a fundamental understanding of how nanoparticles interact with cells. This Feature Article highlights the areas of intersection between physical chemistry and public health in understanding nanoparticle–cell interactions, with a focus on titanium dioxide nanoparticles. It provides an overview of recent research examining the interaction of titanium dioxide nanoparticles with cells in the absence of UV light and provides recommendations for additional nanoparticle–cell research in which physical chemistry expertise could help to inform the public health community. PMID:29111728

Natural dye extract of lawsonia inermis seed as photo sensitizer for titanium dioxide based dye sensitized solar cells.

PubMed

Ananth, S; Vivek, P; Arumanayagam, T; Murugakoothan, P

2014-07-15

Natural dye extract of lawsonia inermis seed were used as photo sensitizer to fabricate titanium dioxide nanoparticles based dye sensitized solar cells. Pure titanium dioxide (TiO2) nanoparticles in anatase phase were synthesized by sol-gel technique and pre dye treated TiO2 nanoparticles were synthesized using modified sol-gel technique by mixing lawsone pigment rich natural dye during the synthesis itself. This pre dye treatment with natural dye has yielded colored TiO2 nanoparticles with uniform adsorption of natural dye, reduced agglomeration, less dye aggregation and improved morphology. The pure and pre dye treated TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Dye sensitized solar cells (DSSC) fabricated using the pre dye treated and pure TiO2 nanoparticles sensitized by natural dye extract of lawsonia inermis seed showed a promising solar light to electron conversion efficiency of 1.47% and 1% respectively. The pre dye treated TiO2 based DSSC showed an improved efficiency of 47% when compared to that of conventional DSSC. Copyright © 2014 Elsevier B.V. All rights reserved.

Photocatalytic effects of titanium dioxide nanoparticles on aquatic organisms-Current knowledge and suggestions for future research.

PubMed

Haynes, Vena N; Ward, J Evan; Russell, Brandon J; Agrios, Alexander G

2017-04-01

Nanoparticles are entering natural systems through product usage, industrial waste and post-consumer material degradation. As the production of nanoparticles is expected to increase in the next decade, so too are predicted environmental loads. Engineered metal-oxide nanomaterials, such as titanium dioxide, are known for their photocatalytic capabilities. When these nanoparticles are exposed to ultraviolet radiation in the environment, however, they can produce radicals that are harmful to aquatic organisms. There have been a number of studies that have reported the toxicity of titanium dioxide nanoparticles in the absence of light. An increasing number of studies are assessing the interactive effects of nanoparticles and ultraviolet light. However, most of these studies neglect environmentally-relevant experimental conditions. For example, researchers are using nanoparticle concentrations and light intensities that are too high for natural systems, and are ignoring water constituents that can alter the light field. The purpose of this review is to summarize the current knowledge of the photocatalytic effects of TiO 2 nanoparticles on aquatic organisms, discuss the limitations of these studies, and outline environmentally-relevant factors that need to be considered in future experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of Histamine in Silages Using Nanomaghemite Core (γ-Fe2O3)-Titanium Dioxide Shell Nanoparticles Off-Line Coupled with Ion Exchange Chromatography

PubMed Central

Cernei, Natalia; Lackova, Zuzana; Guran, Roman; Hynek, David; Skladanka, Jiri; Horky, Pavel; Zitka, Ondrej; Adam, Vojtech

2016-01-01

The presence of biogenic amines is a hallmark of degraded food and its products. Herein, we focused on the utilization of magnetic nanoparticles off-line coupled with ion exchange chromatography with post-column ninhydrin derivatization and Vis detection for histamine (Him) separation and detection. Primarily, we described the synthesis of magnetic nanoparticles with nanomaghemite core (γ-Fe2O3) functionalized with titanium dioxide and, then, applied these particles to specific isolation of Him. To obtain further insight into interactions between paramagnetic particles’ (PMP) surface and Him, a scanning electron microscope was employed. It was shown that binding of histamine causes an increase of relative current response of deprotonated PMPs, which confirmed formation of Him-PMPs clusters. The recovery of the isolation showed that titanium dioxide-based particles were able to bind and preconcentrate Him with recovery exceeding 90%. Finally, we successfully carried out the analyses of real samples obtained from silage. We can conclude that our modified particles are suitable for Him isolation, and thus may serve as the first isolation step of Him from biological samples, as it is demonstrated on alfalfa seed variety Tereza silage. PMID:27626434

In vitro erythemal UV-A protection factors of inorganic sunscreens distributed in aqueous media using carnauba wax-decyl oleate nanoparticles.

PubMed

Villalobos-Hernández, J R; Müller-Goymann, C C

2007-01-01

This paper describes the in vitro photoprotection in the UV-A range, i.e. 320-400 nm obtained by the use of carnauba wax-decyl oleate nanoparticles either as encapsulation systems or as accompanying vehicles for inorganic sunscreens such as barium sulfate, strontium carbonate and titanium dioxide. Lipid-free inorganic sunscreen nanosuspensions, inorganic sunscreen-free wax-oil nanoparticle suspensions and wax-oil nanoparticle suspensions containing inorganic sunscreens dispersed either in their oil phase or their aqueous phase were prepared by high pressure homogenization. The in vitro erythemal UV-A protection factors (EUV-A PFs) of the nanosuspensions were calculated by means of a sun protection analyzer. EUV-A PFs being no higher than 4 were obtained by the encapsulation of barium sulfate and strontium carbonate, meanwhile by the distribution of titanium dioxide in presence of wax-oil nanoparticles, the EUV-A PFs varied between 2 and 19. The increase in the EUV-A PFs of the titanium dioxide obtained by the use of wax-oil nanoparticles demonstrated a better performance of the sun protection properties of this pigment in the UV-A region.

Nanoparticle-Cell Interactions: Relevance for Public Health.

PubMed

Runa, Sabiha; Hussey, Michael; Payne, Christine K

2018-01-25

Nanoparticles, especially metal oxide nanoparticles, are used in a wide range of commercial and industrial applications that result in direct human contact, such as titanium dioxide nanoparticles in paints, food colorings, and cosmetics, or indirectly through release of nanoparticle-containing materials into the environment. Workers who process nanoparticles for downstream applications are exposed to especially high concentrations of nanoparticles. For physical chemists, nanoparticles present an interesting area of study as the small size of nanoparticles changes the properties from that of the bulk material, leading to novel properties and reactivity. For the public health community, this reduction in particle size means that exposure limits and outcomes that were determined from bulk material properties are not necessarily valid. Informed determination of exposure limits requires a fundamental understanding of how nanoparticles interact with cells. This Feature Article highlights the areas of intersection between physical chemistry and public health in understanding nanoparticle-cell interactions, with a focus on titanium dioxide nanoparticles. It provides an overview of recent research examining the interaction of titanium dioxide nanoparticles with cells in the absence of UV light and provides recommendations for additional nanoparticle-cell research in which physical chemistry expertise could help to inform the public health community.

Simulated Sunlight-Mediated Photodynamic Therapy for Melanoma Skin Cancer by Titanium-Dioxide-Nanoparticle-Gold-Nanocluster-Graphene Heterogeneous Nanocomposites.

PubMed

Cheng, Yan; Chang, Yun; Feng, Yanlin; Liu, Ning; Sun, Xiujuan; Feng, Yuqing; Li, Xi; Zhang, Haiyuan

2017-05-01

Simulated sunlight has promise as a light source able to alleviate the severe pain associated with patients during photodynamic therapy (PDT); however, low sunlight utilization efficiency of traditional photosensitizers dramatically limits its application. Titanium-dioxide-nanoparticle-gold-nanocluster-graphene (TAG) heterogeneous nanocomposites are designed to efficiently utilize simulated sunlight for melanoma skin cancer PDT. The narrow band gap in gold nanoclusters (Au NCs), and staggered energy bands between Au NCs, titanium dioxide nanoparticles (TiO 2 NPs), and graphene can result in efficient utilization of simulated sunlight and separation of electron-hole pairs, facilitating the production of abundant hydroxyl and superoxide radicals. Under irradiation of simulated sunlight, TAG nanocomposites can trigger a series of toxicological responses in mouse B16F1 melanoma cells, such as intracellular reactive oxygen species production, glutathione depletion, heme oxygenase-1 expression, and mitochondrial dysfunctions, resulting in severe cell death. Furthermore, intravenous or intratumoral administration of biocompatible TAG nanocomposites in B16F1-tumor-xenograft-bearing mice can significantly inhibit tumor growth and cause severe pathological tumor tissue changes. All of these results demonstrate prominent simulated sunlight-mediated PDT effects. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rational Catalyst Design of Titanium-Silica Materials Aided by Site-Specific Titration Tools

NASA Astrophysics Data System (ADS)

Eaton, Todd Robert

Silica-supported titanium materials are widely used for thermocatalytic applications such as hydroxylation of alkanes and aromatics, oxidation of alcohols and ethers, ammoximation of carbonyls, and sulfoxidations, while Ti-based materials are widely studied for photocatalytic applications such as photo-oxidation of organic substrates and photo-reduction of CO 2. However, the underlying phenomena of how to synthesize, identify, and control the active structures in these materials is not well understood because of the narrow scope of previous work. Studies of titanium-based catalysts typically focus on materials where the metal is present as either highly-dispersed Ti cations or in bulk crystalline TiO2 form, neglecting the numerous and potentially useful intermediate structures. Furthermore, these works typically focus on a single synthesis technique and rely upon bulk characterization techniques to understand the materials. Here rigorous titanium-silica synthesis-structure-function relationships are established by examining several different synthetic method and utilizing characterization techniques that enable an atomic-level understanding of the materials. The materials studied span the range from isolated Ti cations to clustered TiOx domains, polymeric TiO x domains, anatase-like 2D TiO2 domains, and 3D crystalline TiO2. Tools to quantify accessible TiO x and tetrahedral Ti sites are developed, utilizing the selective titration of titanium with phenylphosphonic acid (PPA). Catalytic properties are probed with the photocatalytic oxidation of benzyl alcohol and the thermocatalytic epoxidation of cis-cyclooctene with H2O2 . PPA titration data indicate that the rate of benzyl alcohol photo-oxidation is independent of titanium coordination, while the rate of alkene epoxidation with H2O2 is proportional to the number of tetrahedral titanium sites on the catalyst. PPA titration data also enables the estimation of TiO2 particle size and reveals an important distinction between particle and crystal size, as obtained from XRD. In the course of establishing these relationships we've gained the knowledge of how to control TiO x structure, which enables the design of new and better catalysts. Understanding the synthesis-structure-function relationships allow for the design of a tandem photo/thermocatalytic reaction system for producing and consuming H2O2. By partially overcoating a TiO 2 photocatalyst with a ˜2 nm silica layer we observe a 56-fold rate improvement compared to bare-TiO2 for H2O2 synthesis from the proton-assisted reduction of O2. Addition of metal-SiO2 thermocatalysts (metal=Ti, Nb, or Ta) with sites needed for H2O2 activation creates a tandem system wherein the H2O2 produced in situ is utilized for alkene epoxidation. Compared to a thermocatalytic-only system, the tandem system accelerates epoxidation for cis-cyclooctene(11x faster), styrene(20x) and 1-octene(30x). This approach demonstrates a means for epoxidation with O2 that avoids H2O2 purification and transport, simplifies the total process, provides new opportunities for control by independent H2O2 production and consumption in the same reactor, and enhances rates relative to thermocatalytic-only epoxidation by intimately coupling H2O2 generation and consumption. Critically, establishment of titanium-silica synthesis-structure-function relationships enables the design of new catalysts and systems that are less energy- and material-intensive, leading towards more sustainable chemistry.

From Rockets to Racecars

NASA Technical Reports Server (NTRS)

2005-01-01

NASA s Langley Research Center scientists developed a family of catalysts for low- temperature oxidation of carbon monoxide and other gases. The catalysts provide oxidation of both carbon monoxide and formaldehyde at room temperature without requiring any energy input, just a suitable flow of gas through them. Originally designed as part of an atmospheric satellite project, where the catalysts were intended to recycle and recapture carbon dioxide to enhance the operational life of carbon dioxide lasers, the entire system was made to be rugged, long-lived, and fail-safe. The low-temperature oxidation catalysts can be produced and coated onto various catalyst supports, including porous ceramic monoliths and beads, which means that they can be integrated into existing designs, made to fit in limited space, and fashioned into a variety of geometrically different products. Although the satellite project was never launched, the resulting catalysts are doing great things here on Earth, with current applications in the high-speed motor sports arena as air purifiers, so professional racecar drivers do not get carbon monoxide poisoning. Future benefits may extend even further.

Atmosphere Processing Module Automation and Catalyst Durability Analysis for Mars ISRU Pathfinder

NASA Technical Reports Server (NTRS)

Petersen, Elspeth M.

2016-01-01

The Mars In-Situ Resource Utilization Pathfinder was designed to create fuel using components found in the planet’s atmosphere and regolith for an ascension vehicle to return a potential sample return or crew return vehicle from Mars. The Atmosphere Processing Module (APM), a subunit of the pathfinder, uses cryocoolers to isolate and collect carbon dioxide from Mars simulant gas. The carbon dioxide is fed with hydrogen into a Sabatier reactor where methane is produced. The APM is currently undergoing the final stages of testing at Kennedy Space Center prior to process integration testing with the other subunits of the pathfinder. The automation software for the APM cryocoolers was tested and found to perform nominally. The catalyst used for the Sabatier reactor was investigated to determine the factors contributing to catalyst failure. The results from the catalyst testing require further analysis, but it appears that the rapid change in temperature during reactor start up or the elevated operating temperature is responsible for the changes observed in the catalyst.

Full Scale Alternative Catalyst Testing for Bosch Reactor Optimization

NASA Technical Reports Server (NTRS)

Barton, Katherine; Abney, Morgan B.

2011-01-01

Current air revitalization technology onboard the International Space Station (ISS) cannot provide complete closure of the oxygen and hydrogen loops. This makes re-supply necessary, which is possible for missions in low Earth orbit (LEO) like the ISS, but unviable for long term space missions outside LEO. In comparison, Bosch technology reduces carbon dioxide with hydrogen, traditionally over a steel wool catalyst, to create water and solid carbon. The Bosch product water can then be fed to the oxygen generation assembly to produce oxygen for crew members and hydrogen necessary to reduce more carbon dioxide. Bosch technology can achieve complete oxygen loop closure, but has many undesirable factors that result in a high energy, mass, and volume system. Finding a different catalyst with an equal reaction rate at lower temperatures with less catalyst mass and longer lifespan would make a Bosch flight system more feasible. Developmental testing of alternative catalysts for the Bosch has been performed using the Horizontal Bosch Test Stand. Nickel foam, nickel shavings, and cobalt shavings were tested at 500 C and compared to the original catalyst, steel wool. This paper presents data and analysis on the performance of each catalyst tested at comparable temperatures and recycle flow rates.

Enhanced sun protection of nano-sized metal oxide particles over conventional metal oxide particles: an in vitro comparative study.

PubMed

Singh, P; Nanda, A

2014-06-01

A systematic and detailed study has been designed and conducted, taking into account some of the proposed benefits such as increased efficiency, transparency, unique texture, protection of active ingredient and higher consumer compliance of cosmetics containing nano-sized metal oxides. This study also presents an in vitro method to determine sun protection factor of the investigational sunscreen cream samples containing zinc oxide and titanium dioxide with a varied range of particle size. Finally, a comparative study has been conducted between metal oxide particles, conventional as well as nanoparticles. All the skin cosmetics formulated were thermally stable with a pH ranging from 7.9 to 8.2. Moreover, the fatty acid substance content and residue were found to be analogous to the standard values in each skin cosmetic. The skin cosmetics containing the titanium or zinc oxide nanoparticles were found to have improved spreadability as compared to skin cosmetics containing conventional titanium or zinc oxide particles, respectively. All skin cosmetics were found to have uniform distribution of the particles. The sunscreen creams containing zinc oxide nanoparticles and titanium dioxide nanoparticles were found to have higher in vitro sun protection factor (SPF of 3.65 for ZnO nanoparticles and 4.93 for TiO2 nanoparticles) as compared to that of sunscreen creams containing conventional zinc oxide particles (SPF = 2.90) and conventional titanium dioxide (SPF = 1.29), clearly indicating the effect of reduction in particles size, from micro to nano, on the sun protection factor. Good texture, better spreadability and enhanced in vitro SPF proved the advantageous role of nanoparticles in cosmetics. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Aminopyridinate-FI hybrids, their hafnium and titanium complexes, and their application in the living polymerization of 1-hexene.

PubMed

Haas, Isabelle; Dietel, Thomas; Press, Konstantin; Kol, Moshe; Kempe, Rhett

2013-10-11

Based on two well-established ligand systems, the aminopyridinato (Ap) and the phenoxyimine (FI) ligand systems, new Ap-FI hybrid ligands were developed. Four different Ap-FI hybrid ligands were synthesized through a simple condensation reaction and fully characterized. The reaction of hafnium tetrabenzyl with all four Ap-FI hybrid ligands exclusively led to mono(Ap-FI) complexes of the type [(Ap-FI)HfBn2 ]. The ligands acted as tetradentate dianionic chelates. Upon activation with tris(pentafluorophenyl)borane, the hafnium-dibenzyl complexes led to highly active catalysts for the polymerization of 1-hexene. Ultrahigh molecular weights and extremely narrow polydispersities support the living nature of this polymerization process. A possible deactivation product of the hafnium catalysts was characterized by single-crystal X-ray analysis and is discussed. The coordination modes of these new ligands were studied with the help of model titanium complexes. The reaction of titanium(IV) isopropoxide with ligand 1 led to a mono(Ap-FI) complex, which showed the desired fac-mer coordination mode. Titanium (IV) isopropoxide reacted with ligand 4 to give a complex of the type [(ApH-FI)2 Ti(OiPr)2 ], which featured the ligand in its monoanionic form. The two titanium complexes were characterized by X-ray crystal-structure analysis. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of a novel porous titanium silicate/g-C{sub 3}N{sub 4} hybrid nanocomposite catalyst for environmental applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adepu, Ajay Kumar; Narayanan, Venkatathri, E-mail: venkatathrin@yahoo.com, E-mail: ajay.kumar553@gmail.com

2016-04-13

Herein we developed a novel porous Titanium silicate/g-C{sub 3}N{sub 4} (TSCN) hybrid composite with a inorganic-organic heterojunction. The synthesized porous TSCN were well characterized by various analytical techniques for structural and chemical properties evaluation. FESEM results shows the growth of finely distributed porous titanium silicate on the surface of the g-C{sub 3}N{sub 4}. Porous TSCN hybrid nanocomposite has a great influence on the electronic and optical properties.

Hydrothermal growth and characterization of titanium dioxide nanostructures for use in dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Sorge, Judith D.

As the world's energy needs continue to grow, next generation photovoltaic cells are in high demand because they offer the possibility of an inexpensive alternative to current energy production techniques. Dye sensitized solar cells (DSSC's), utilize common materials and low cost commercialization techniques, which make them a compelling choice for research in this area. This research focuses on the titanium dioxide coating, which transfers electrons from the photoactive dye to the electrode. 3-4% efficient DSSC's using doctor bladed titanium dioxide coatings with a specific surface area of 55-60m2/g have been demonstrated in our laboratory. To enhance the efficiency of these cells, both the surface area and the electron conduction of the titania layer must be optimized. This has been done by utilizing high aspect ratio nanoparticles of titania instead of mesoporous layers formed with spherical particles. Anodization of titanium metal or anodic alumina membrane templating are common ways to produce nanorods, but involve complex processes leading toward expensive commercialization. This research instead focuses on the hydrothermal growth of nanofibrous titania on a titanium metal substrate, removing the need for dispersion and deposition procedures as well as using a low temperature processing method. Depending upon the formulation utilized, a variety of structures can be produced, from thick carpets of nanofiber strands to large platelets. The composition and morphology of the products have been characterized with respect to the growth conditions using electron microscopy, energy dispersive spectroscopy and x-ray diffraction. The compositional analysis is used to investigate the complicated reaction mechanisms in the system. Coatings of titania nanotubes were then tested in the DSSC's, as were those with the titanium metal substrate acting as the photo anode. Modeling the geometric parameters of the different pore structures of the coatings helps us to understand the advantages afforded by these new cells.

Impact of Nanoparticles and Natural Organic Matter on the Removal of Organic Pollutants by Activated Carbon Adsorption

EPA Science Inventory

Isotherm experiments evaluating trichloroethylene (TCE) adsorption onto powdered activated carbon (PAC) were conducted in the presence and absence of three commercially available nanomaterials— iron oxide (Fe2O3), titanium dioxide (TiO2), and silicon dioxide (SiO2). Isotherm exp...

Catalyst systems and uses thereof

DOEpatents

Ozkan, Umit S [Worthington, OH; Holmgreen, Erik M [Columbus, OH; Yung, Matthew M [Columbus, OH

2012-07-24

A method of carbon monoxide (CO) removal comprises providing an oxidation catalyst comprising cobalt supported on an inorganic oxide. The method further comprises feeding a gaseous stream comprising CO, and oxygen (O.sub.2) to the catalyst system, and removing CO from the gaseous stream by oxidizing the CO to carbon dioxide (CO.sub.2) in the presence of the oxidation catalyst at a temperature between about 20 to about 200.degree. C.

Electrochemical device for converting carbon dioxide to a reaction product

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masel, Richard I.; Chen, Qingmei; Liu, Zengcai

An electrochemical device converts carbon dioxide to a reaction product. The device includes an anode and a cathode, each comprising a quantity of catalyst. The anode and cathode each has reactant introduced thereto. A polymer electrolyte membrane is interposed between the anode and the cathode. At least a portion of the cathode catalyst is directly exposed to gaseous carbon dioxide during electrolysis. The average current density at the membrane is at least 20 mA/cm.sup.2, measured as the area of the cathode gas diffusion layer that is covered by catalyst, and CO selectivity is at least 50% at a cell potentialmore » of 3.0 V. In some embodiments, the polymer electrolyte membrane comprises a polymer in which a constituent monomer is (p-vinylbenzyl)-R, where R is selected from the group consisting of imidazoliums, pyridiniums and phosphoniums. In some embodiments, the polymer electrolyte membrane is a Helper Membrane comprising a polymer containing an imidazolium ligand, a pyridinium ligand, or a phosphonium ligand.« less

Binary effect of titanium dioxide nanoparticles (nTio2) and phosphorus on microalgae (Chlorella 'Ellipsoides Gerneck, 1907).

PubMed

Matouke, Moise M; Elewa, Dorcas T; Abdullahi, Karimatu

2018-05-01

The wide application of titanium dioxide nanoparticles and phosphorus in the manufacturing of many industrial products mainly used in agricultural sector has resulted in the release of considerable amounts of these compounds into freshwater aquatic ecosystem. These compounds may cause some unexpected effects to aquatic organisms. This study assessed the binary effects of Titanium nanoparticles (nTiO 2 ) and Phosphorus on Chlorella ellipsoides. Toxicological assay test of the compounds nTiO 2 (1.25 μM) alone and the combination of Titanium dioxide (1.25 μM) and Phosphorus (16, 32, 80, 160, 240 μM) was assessed, after 96 h exposures, for optical density (OD 680 ), specific growth rate, chlorophyll levels and lipid peroxidation via Malondialdehyde (MDA) activity. Superoxide dismutase (SOD), peroxidase (POD) and glutathione-s-transferase (GST) activities were also measured. Two-way ANOVA showed a significant interaction (P < 0.05) between binary mixture. Co-exposure showed a decreased phosphorus bioconcentration in the microalgae with significant increase (P < 0.05) in chlorophyll a/b and total chlorophyll contents. A significant decrease (P < 0.05) in specific growth rate and optical density were recorded whereas, antioxidant enzymes (MDA, SOD, POD, GST) activities were significantly (P < 0.05) increased. These results showed that the addition of nTiO 2 to Phosphorus affected the physiology of microalgae and should be of great concern for freshwater biodiversity. Copyright © 2018. Published by Elsevier B.V.

Multi-stage catalyst systems and uses thereof

DOEpatents

Ozkan, Umit S [Worthington, OH; Holmgreen, Erik M [Columbus, OH; Yung, Matthew M [Columbus, OH

2009-02-10

Catalyst systems and methods provide benefits in reducing the content of nitrogen oxides in a gaseous stream containing nitric oxide (NO), hydrocarbons, carbon monoxide (CO), and oxygen (O.sub.2). The catalyst system comprises an oxidation catalyst comprising a first metal supported on a first inorganic oxide for catalyzing the oxidation of NO to nitrogen dioxide (NO.sub.2), and a reduction catalyst comprising a second metal supported on a second inorganic oxide for catalyzing the reduction of NO.sub.2 to nitrogen (N.sub.2).

40 CFR 91.329 - Catalyst thermal stress test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... composition: Constituent Volumepercent Parts per million Carbon Monoxide 1 1 Oxygen 1.3 Carbon Dioxide 9 Water Vapor 10 Sulfur Dioxide 20 Oxides of Nitrogen 280 Hydrogen 3500 Hydrocarbon 1,2 4000 Nitrogen=Balance 1...

40 CFR 91.329 - Catalyst thermal stress test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... composition: Constituent Volumepercent Parts per million Carbon Monoxide 1 1 Oxygen 1.3 Carbon Dioxide 9 Water Vapor 10 Sulfur Dioxide 20 Oxides of Nitrogen 280 Hydrogen 3500 Hydrocarbon 1,2 4000 Nitrogen=Balance 1...

40 CFR 91.329 - Catalyst thermal stress test.

Code of Federal Regulations, 2014 CFR

2014-07-01

... composition: Constituent Volumepercent Parts per million Carbon Monoxide 1 1 Oxygen 1.3 Carbon Dioxide 9 Water Vapor 10 Sulfur Dioxide 20 Oxides of Nitrogen 280 Hydrogen 3500 Hydrocarbon 1,2 4000 Nitrogen=Balance 1...

Processing Method for Creating Ultra-Thin Lead Zirconate Titanate (PZT) Films Via Chemical Solution Deposition

DTIC Science & Technology

2008-12-01

n-propoxide and titanium isopropoxide , were measured with a graduated auto pipet and combined with 45 mL of 2-MOE in a 125 mL flask. The solution...nitrogen (N2). This anneal procedure was used to remove trapped hydrogen from the thin film. Following the anneal, a bi-layer of titanium (Ti) and...dioxide Ti titanium 10 NO. OF COPIES ORGANIZATION 1 ADMNSTR ELEC DEFNS TECHL INFO CTR ATTN DTIC OCP 8725 JOHN J KINGMAN RD STE

Imidazolium-Functionalized Carbon Nanohorns for the Conversion of Carbon Dioxide: Unprecedented Increase of Catalytic Activity after Recycling.

PubMed

Calabrese, Carla; Liotta, Leonarda F; Carbonell, Esther; Giacalone, Francesco; Gruttadauria, Michelangelo; Aprile, Carmela

2017-03-22

Six new hybrid materials composed of carbon nanohorns (CNHs) and highly cross-linked imidazolium salts were easily synthesized using a one-step procedure based on the radical oligomerization of bis-vinylimidazolium salts (bVImiX) in the presence of pristine CNHs. The hybrid materials were characterized and employed as the sole catalysts for the conversion of carbon dioxide into cyclic carbonate by reaction with epoxides. The solids displayed excellent turnover number and productivity. Moreover, four catalysts were investigated in recycling experiments. Two catalysts containing an octyl linker between the imidazolium units and a bromide or an iodide anion showed no loss in activity after three cycles. The other two catalysts containing a p-xylyl linker and a bromide anion and different CNHs/bVImiX ratios showed an unprecedented increase of activity after recycling. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Gold Nanoparticles Addition to CuO–ZnO/A₂O₃ Catalyst in Conversion of Carbon Dioxide to Methanol.

PubMed

Kim, Ki-Joong; Ahn, Ho-Geun

2017-04-01

Hydrogenation of carbon dioxide (CO₂) into methanol (CH₃OH) was carried out in the CuO–ZnO based supported gold catalyst prepared by the co-precipitation method. When gold nanoparticles were added to the CuO–ZnO/Al2O₃ catalysts (CuO–ZnO/Au/Al₂O₃), the CO₂ conversion and CH₃OH yield were increased (two times higher than that of CuO–ZnO/Al₂O₃ catalyst) with increasing reaction pressure, but selectivity of CH3OH was decreased. The main reason of this result could suggest the importance gold-oxides interface in CH₃OH formation through hydrogenation of CO₂. Maximum selectivity and yield to CH₃OH over CuO–ZnO/Au/Al₂O₃ were obtained at 250°C and under 15–20 bars.

Metallic tin quantum sheets confined in graphene toward high-efficiency carbon dioxide electroreduction

NASA Astrophysics Data System (ADS)

Lei, Fengcai; Liu, Wei; Sun, Yongfu; Xu, Jiaqi; Liu, Katong; Liang, Liang; Yao, Tao; Pan, Bicai; Wei, Shiqiang; Xie, Yi

2016-09-01

Ultrathin metal layers can be highly active carbon dioxide electroreduction catalysts, but may also be prone to oxidation. Here we construct a model of graphene confined ultrathin layers of highly reactive metals, taking the synthetic highly reactive tin quantum sheets confined in graphene as an example. The higher electrochemical active area ensures 9 times larger carbon dioxide adsorption capacity relative to bulk tin, while the highly-conductive graphene favours rate-determining electron transfer from carbon dioxide to its radical anion. The lowered tin-tin coordination numbers, revealed by X-ray absorption fine structure spectroscopy, enable tin quantum sheets confined in graphene to efficiently stabilize the carbon dioxide radical anion, verified by 0.13 volts lowered potential of hydroxyl ion adsorption compared with bulk tin. Hence, the tin quantum sheets confined in graphene show enhanced electrocatalytic activity and stability. This work may provide a promising lead for designing efficient and robust catalysts for electrolytic fuel synthesis.

Behavior of engineered nanoparticles in aqueous solutions and porous media: Connecting experimentation to probabilistic analysis

NASA Astrophysics Data System (ADS)

Contreras, Carolina

2011-12-01

Engineered nanoparticles have enhanced products and services in the fields of medicine, energy, engineering, communications, personal care, environmental treatment, and many others. The increased use of engineered nanoparticles in consumer products will lead to these materials in natural systems, inevitably becoming a potential source of pollution. The study of the stability and mobility of these materials is fundamental to understand their behavior in natural systems and predict possible health and environmental implications. In addition, the use of probabilistic methods such as sensitivity analysis applied to the parameters controlling their behavior is useful in providing support in performing a risk assessment. This research investigated the stability and mobility of two types of metal oxide nanoparticles (aluminum oxide and titanium dioxide). The stability studies tested the effect of sand, pH 4, 7, and 10, and the NaCl in concentrations of 10mM, 25mM, 50mM, and 75mM. The mobility was tested using saturated quartz sand columns and nanoparticles suspension at pH 4 and 7 and in the presence of NaCl and CaCl2 in concentrations of 0.1mM, 1mM, and 10mM. Additionally, this work performed a sensitivity analysis of physical parameters used in mobility experiment performed for titanium dioxide and in mobility experiments taken from the literature for zero valent iron nanoparticles and fluorescent colloids to determine their effect on the value C/Co of by applying qualitative and quantitative methods. The results from the stability studies showed that titanium dioxide nanoparticles (TiO2) could remain suspended in solution for up to seven days at pH 10 and pH 7 even after settling of the sand; while for pH 4 solutions titanium settled along with the sand and after seven days no particles were observed in suspension. Other stability studies showed that nanoparticle aluminum oxide (Al2O3) and titanium dioxide (TiO2) size increased with increasing ionic strength (10 to 75 mM NaCl). The results from the mobility experiments showed that ionic strength has more effect on aluminum oxide nanoparticles mobility than on titanium oxide nanoparticles mobility. For Al2O3 25% of the initial concentration was obtained in the effluent whereas for TiO2 less than the 10% of the initial concentration was observed. In general, when the ionic strength was increased the effluent of nanoparticles decreased. Collision efficiencies calculated base on the colloid filtration theory were consistent with the mobility experiments. Results from sensitivity analysis showed that for zero valent iron nanoparticles and fluorescent colloids porous medium diameter and porosity were the parameters that most influenced the variability of C/Co whereas for titanium dioxide nanoparticles C/Co was more sensitive to column length and pore water velocity.

Enhanced electron transfer and silver-releasing suppression in Ag-AgBr/titanium-doped Al2O3 suspensions with visible-light irradiation.

PubMed

Zhou, Xuefeng; Hu, Chun; Hu, Xuexiang; Peng, Tianwei

2012-06-15

Ag-AgBr was deposited onto mesoporous alumina (MA) and titanium-doped MA by a deposition-precipitation method. The photocatalytic activity and the dissolution of Ag(+) from different catalysts were investigated during the photodegradation of 2-chlorophenol (2-CP) and phenol in ultrapure water and tap water with visible-light irradiation. With the increase in doped titanium, the Ag(+) dissolution decreased with a decrease in the photocatalytic activity. Ag-AgBr/MA-Ti1 was considered the better catalyst for practical applications because its Ag(+) dissolution was minimal (0.4 mg L(-1) in ultrapure water and 5 μg L(-1) in tap water), although its photoactivity was slightly less than that of Ag-AgBr/MA. The dissolution of Ag(+) was related to a charge-transfer process based on the study of cyclic voltammetry analyses under a variety of experimental conditions. The results suggested that several types of anions in the water, including CO(3)(2-), SO(4)(2-), and Cl(-), could act as electron donors that trap the photogenerated holes on Ag nanoparticles to facilitate electron circulation; this would decrease the release of Ag(+). Our studies indicated that the catalyst had a higher activity and stability in water purification. Copyright © 2012. Published by Elsevier B.V.

Understanding trends in electrochemical carbon dioxide reduction rates

DOE PAGES

Liu, Xinyan; Xiao, Jianping; Peng, Hongjie; ...

2017-05-22

Electrochemical carbon dioxide reduction to fuels presents one of the great challenges in chemistry. Herein we present an understanding of trends in electrocatalytic activity for carbon dioxide reduction over different metal catalysts that rationalize a number of experimental observations including the selectivity with respect to the competing hydrogen evolution reaction. We also identify two design criteria for more active catalysts. The understanding is based on density functional theory calculations of activation energies for electrochemical carbon monoxide reduction as a basis for an electrochemical kinetic model of the process. Furthermore, we develop scaling relations relating transition state energies to the carbonmore » monoxide adsorption energy and determine the optimal value of this descriptor to be very close to that of copper.« less

Understanding trends in electrochemical carbon dioxide reduction rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xinyan; Xiao, Jianping; Peng, Hongjie

Electrochemical carbon dioxide reduction to fuels presents one of the great challenges in chemistry. Herein we present an understanding of trends in electrocatalytic activity for carbon dioxide reduction over different metal catalysts that rationalize a number of experimental observations including the selectivity with respect to the competing hydrogen evolution reaction. We also identify two design criteria for more active catalysts. The understanding is based on density functional theory calculations of activation energies for electrochemical carbon monoxide reduction as a basis for an electrochemical kinetic model of the process. Furthermore, we develop scaling relations relating transition state energies to the carbonmore » monoxide adsorption energy and determine the optimal value of this descriptor to be very close to that of copper.« less

Vacancy-type defects in TiO2/SiO2/SiC dielectric stacks

NASA Astrophysics Data System (ADS)

Coleman, P. G.; Burrows, C. P.; Mahapatra, R.; Wright, N. G.

2007-07-01

Open-volume (vacancy-type) point defects have been observed in ˜80-nm-thick titanium dioxide films grown on silicon dioxide/4H silicon carbide substrates as stacks with high dielectric constant for power device applications, using variable-energy positron annihilation spectroscopy. The concentration of vacancies decreases as the titanium dioxide growth temperature is increased in the range from 700to1000°C, whereas grain boundaries form in the polycrystalline material at the highest growth temperatures. It is proposed that the optimal electrical performance for films grown at 800°C reflects a balance between decreasing vacancy concentration and increasing grain boundary formation. The concentration of vacancies at the silicon dioxide/silicon carbide interface appears to saturate after 2.5h oxidation at 1150°C. A supplementary result suggests that the quality of the 10-μm-thick deposited silicon carbide epilayer is compromised at depths of about 2μm and beyond, possibly by the migration of impurities and/or other defects from the standard-grade highly doped 4H silicon carbide wafer beneath the epilayer during oxidation.

Grafting strategy to develop single site titanium on an amorphous silica surface.

PubMed

Capel-Sanchez, M C; Blanco-Brieva, G; Campos-Martin, J M; de Frutos, M P; Wen, W; Rodriguez, J A; Fierro, J L G

2009-06-16

Titanium/silica systems were prepared by grafting a titanium alkoxide (titanium isopropoxide and titanium (triethanolaminate) isopropoxide) precursor onto amorphous silica. The grafting process, which consisted of the hydrolysis of the Ti precursor by the hydroxyl groups on the silica surface, yielded samples containing Ti-loadings of 1-1.6 wt %. The as synthesized and calcined TiO(2)-SiO(2) samples were characterized by UV-vis, FTIR, XPS, and XANES spectroscopic techniques. These systems were tested in the liquid-phase epoxidation of oct-1-ene with hydrogen peroxide reaction. Spectroscopic data indicated that titanium anchoring takes place by reaction between the alkoxide precursor and surface OH groups of the silica substrate. The nature of surface titanium species generated by chemical grafting depends largely on the titanium precursor employed. Thus, the titanium isopropoxide precursor yields tetrahedrally coordinated polymeric titanium species, which give rise to a low-efficiency catalyst. However, if an atrane precursor (titanium (triethanolaminate) isopropoxide) is employed, isolated titanium species are obtained. The fact that these species remain isolated even after calcination is due to the protective effect of the triethanolaminate ligand that avoids titanium polymerization. These differences in the titanium environment have a pivotal role in the performance of these systems in the epoxidation of alkenes with hydrogen peroxide.

Grafting Strategy to Develop Single Site Titanium on an Amorphous Silica Surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capel-Sanchez, M.; Blanco-Brieva, G; Campos-Martin, J

2009-01-01

Titanium/silica systems were prepared by grafting a titanium alkoxide (titanium isopropoxide and titanium (triethanolaminate) isopropoxide) precursor onto amorphous silica. The grafting process, which consisted of the hydrolysis of the Ti precursor by the hydroxyl groups on the silica surface, yielded samples containing Ti-loadings of 1-1.6 wt %. The as synthesized and calcined TiO2-SiO2 samples were characterized by UV-vis, FTIR, XPS, and XANES spectroscopic techniques. These systems were tested in the liquid-phase epoxidation of oct-1-ene with hydrogen peroxide reaction. Spectroscopic data indicated that titanium anchoring takes place by reaction between the alkoxide precursor and surface OH groups of the silica substrate.more » The nature of surface titanium species generated by chemical grafting depends largely on the titanium precursor employed. Thus, the titanium isopropoxide precursor yields tetrahedrally coordinated polymeric titanium species, which give rise to a low-efficiency catalyst. However, if an atrane precursor (titanium (triethanolaminate) isopropoxide) is employed, isolated titanium species are obtained. The fact that these species remain isolated even after calcination is due to the protective effect of the triethanolaminate ligand that avoids titanium polymerization. These differences in the titanium environment have a pivotal role in the performance of these systems in the epoxidation of alkenes with hydrogen peroxide.« less

Effect of growth time on the structure, morphology and optical properties of hydrothermally synthesized TiO2 nanorod thin films

NASA Astrophysics Data System (ADS)

Mohapatra, A. K.; Nayak, J.

2018-05-01

Titanium dioxide (TiO2) nanorod thin films were deposited on fluorine doped tin oxide coated glass substrates by a single step rapid hydrothermal process. The concentration of the precursor, the temperature of the reaction mixture were optimized in order to enhance the rate of deposition. Unlike the previously reported hydrothermal treatment for 24 - 48 h, the deposition of well aligned titanium dioxide nanorods was achieved in a short time such as 3 - 8 h. The crystal structure of the films were investigated by X-rays diffraction. The morphology of the nanorod films were studied with scanning electron microscopy. The optical properties were studied by photoluminescence spectroscopy.

Structure and optical properties of TiO2 thin films deposited by ALD method

NASA Astrophysics Data System (ADS)

Szindler, Marek; Szindler, Magdalena M.; Boryło, Paulina; Jung, Tymoteusz

2017-12-01

This paper presents the results of study on titanium dioxide thin films prepared by atomic layer deposition method on a silicon substrate. The changes of surface morphology have been observed in topographic images performed with the atomic force microscope (AFM) and scanning electron microscope (SEM). Obtained roughness parameters have been calculated with XEI Park Systems software. Qualitative studies of chemical composition were also performed using the energy dispersive spectrometer (EDS). The structure of titanium dioxide was investigated by X-ray crystallography. A variety of crystalline TiO2 was also confirmed by using the Raman spectrometer. The optical reflection spectra have been measured with UV-Vis spectrophotometry.

Far-ultraviolet spectral changes of titanium dioxide with gold nanoparticles by ultraviolet and visible light.

PubMed

Tanabe, Ichiro; Kurawaki, Yuji

2018-05-15

Attenuated total reflectance spectra including the far-ultraviolet (FUV, ≤200nm) region of titanium dioxide (TiO 2 ) with and without gold (Au) nanoparticles were measured. A newly developed external light-irradiation system enabled to observe spectral changes of TiO 2 with Au nanoparticles upon light irradiations. Absorption in the FUV region decreased and increased by the irradiation with ultraviolet and visible light, respectively. These spectral changes may reflect photo-induced electron transfer from TiO 2 to Au nanoparticles under ultraviolet light and from Au nanoparticles to TiO 2 under visible light, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Adsorption of polymethacrylic acid from aqueous solutions on disperse titanium dioxide

NASA Astrophysics Data System (ADS)

Yaremko, Z. M.; Tkachenko, N. G.; Fedushinskaya, L. B.

2011-10-01

The state of macromolecules of polymethacrylic acid adsorbed on the surface of disperse titanium dioxide was assessed using a combination of the differential concentration approach to the determination of adsorption and methods for determining the size of disperse adsorbents by dynamic light scattering and sedimentation analysis in the field of centrifugal forces. Three sections were found on the isotherm of adsorption: in the first, isolated islands of adsorbed macromolecules formed; in the second, layers of macromolecules with a different degree of deformation were observed; in the third, determining the adsorption of macromolecules is complicated by other accompanying processes, and assessing the state of macromolecules in the adsorption layer becomes difficult.

Investigation of the SERS Spectra of Hydroquinone Molecule Adsorbed on Titanium Dioxide

NASA Astrophysics Data System (ADS)

Polubotko, A. M.; Chelibanov, V. P.

2018-01-01

The paper analyzes the SERS spectrum of hydroquinone adsorbed on nanoparticles of titanium dioxide (TiO2). It is seen that the enhancement is stronger for a larger mean size of nanoparticles that is in agreement with an electrostatic approximation. In addition, it is found that there are the lines, which are forbidden in usual Raman spectra. There is also an enhancement caused both by the normal and tangential components of the electric field. This result is in agreement with the theory of SERS on semiconductor and dielectric substrates. The discovery of the forbidden lines indicates on the sufficiently large role of the strong quadrupole light-molecule interaction in such a system.

TiO2 nanocomposite for the controlled release of drugs against pathogens causing wound infections

NASA Astrophysics Data System (ADS)

Devanand Venkatasubbu, G.; Nagamuthu, S.; Anusuya, T.; Kumar, J.; Chelliah, Ramachandran; Rani Ramakrishnan, Sudha; Antony, Usha; Khan, Imran; Oh, Deog-Hwan

2018-02-01

Chitosan titanium dioxide nanocomposite has been used for wound healing. Titanium dioxide (TiO2) nanoparticles are synthesised and made in to nanocomposite along with chitosan. Curcumin nanoparticles are synthesised. Three different drugs with antimicrobial activity are incorporated into the chitosan/TiO2nanocomposite. Ciprofloxacin, amoxicillin and curcumin nanoparticles are incorporated within the chitosan/TiO2 nanoparticles. The nanoparticles and nanocomposite are characterized with XRD, FTIR, TEM and SEM. Drug loading was found to be around 45% for all the three drug molecules. The drug release profile shows a controlled release of drug molecules from the nanocomposite. Antibacterial studies shows a good inhibition of bacterial species by the nanocomposites.

Study on the decomposition of trace benzene over V2O5–WO3/TiO2-based catalysts in simulated flue gas

EPA Science Inventory

Trace levels (1 and 10 ppm) of gaseous benzene were catalytically decomposed in a fixed-bed catalytic reactor with monolithic oxides of vanadium and tungsten supported on titanium oxide (V2O5–WO3/TiO2) catalysts under conditions simulating the cooling of waste incineration flue g...

Water leaching of titanium from ore flotation residue.

PubMed

Jaworska, Malgorzata M; Guibal, Eric

2003-01-01

Copper ore tailings were tested for the stability of titanium submitted to water leaching in three different reactor systems (agitated vessel, bioreactor and percolated fixed-bed column). For each of these systems, titanium extraction did not exceed 1% of the available metal. Biomass removed from ore residue adsorbed a small part of the titanium with sorption capacities below 20-30 mg g(-1), but most of this biomass was sequestered in the ore residue. Oxygen and carbon dioxide concentrations were monitored and changes in concentration correlated with bacteria development at the initial stage of the process and to fungal development in the latter stages.

Synthesis of Hydroxide-TiO2 Compounds with Photocatalytic Activity for Degradation of Phenol

NASA Astrophysics Data System (ADS)

Contreras-Ruiz, J. C.; Martínez-Gallegos, S.; Ordoñez, E.; González-Juárez, J. C.; García-Rivas, J. L.

2017-03-01

Photocatalytic degradation of phenol using titanium dioxide (TiO2), either alone or in combination with other materials, has been tested. Mg/Al hydrotalcites prepared by two methods using inorganic (HC) or organic (HS) chemical reagents, along with mixed oxides produced by calcination of these products (HCC and HSC), were mixed with titanium isopropoxide to obtain hydroxide-TiO2 compounds (HCC-TiO2 and HSC-TiO2) and their photocatalytic activity tested in solutions of 10 mg/L phenol at 120 min under illumination at λ UV = 254 nm with power of 4 W or 8 W. The obtained materials were characterized by various techniques, revealing that TiO2 was incorporated into the mixed oxides of the calcined hydrotalcite to form the above-mentioned compounds. The photocatalytic test results indicate that the activity of HCC-TiO2 can be attributed to increased phenol adsorption by hydrotalcite for transfer to the active photocatalytic phase of the impregnated TiO2 particles, while the better results obtained for HSC-TiO2 are due to greater catalyst impregnation on the surface of the calcined hydrotalcite, reducing the screening phenomenon and achieving HSC-TiO2 degradation of up to 21.0% at 8 W. Reuse of both compounds indicated tight combination of HCC or HSC with TiO2, since in four successive separation cycles there was little reduction of activity, being associated primarily with material loss during recovery.

Design of catalytic monoliths for closed-cycle carbon dioxide lasers

NASA Technical Reports Server (NTRS)

Herz, R. K.; Guinn, K.; Goldblum, S.; Noskowski, E.

1989-01-01

Pulsed carbon dioxide (CO2) lasers have many applications in aeronautics, space research, weather monitoring and other areas. Full exploitation of the potential of these lasers in hampered by the dissociation of CO2 that occurs during laser operation. The development of closed-cycle CO2 lasers requires active CO-O2 recombination (CO oxidation) catalyst and design methods for implementation of catalysts in CO2 laser systems. A monolith catalyst section model and associated design computer program, LASCAT, are presented to assist in the design of a monolith catalyst section of a closed cycle CO2 laser system. Using LASCAT,the designer is able to specify a number of system parameters and determine the monolith section performance. Trade-offs between the catalyst activity, catalyst dimensions, monolith dimensions, pressure drop, O2 conversion, and other variables can be explored and adjusted to meet system design specifications. An introduction describes a typical closed-cycle CO2 system, and indicates some advantages of a closed cycle laser system over an open cycle system and some advantages of monolith support over other types of supports. The development and use of a monolith catalyst model is presented. The results of a design study and a discussion of general design rules are given.

Carbon dioxide hydrogenation catalysed by well-defined Mn(i) PNP pincer hydride complexes† †Electronic supplementary information (ESI) available: Experimental procedures, NMR and IR spectra, atomic coordinates for DFT optimized structures and computational details, and crystallographic data for 2. CCDC 1520528. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc00209b Click here for additional data file. Click here for additional data file.

PubMed Central

Bertini, Federica; Glatz, Mathias; Gorgas, Nikolaus; Stöger, Berthold; Peruzzini, Maurizio; Veiros, Luis F.

2017-01-01

The catalytic reduction of carbon dioxide is of great interest for its potential as a hydrogen storage method and to use carbon dioxide as C-1 feedstock. In an effort to replace expensive noble metal-based catalysts with efficient and cheap earth-abundant counterparts, we report the first example of Mn(i)-catalysed hydrogenation of CO2 to HCOOH. The hydride Mn(i) catalyst [Mn(PNPNH-iPr)(H)(CO)2] showed higher stability and activity than its Fe(ii) analogue. TONs up to 10 000 and quantitative yields were obtained after 24 h using DBU as the base at 80 °C and 80 bar total pressure. At catalyst loadings as low as 0.002 mol%, TONs greater than 30 000 could be achieved in the presence of LiOTf as the co-catalyst, which are among the highest activities reported for base-metal catalysed CO2 hydrogenations to date. PMID:28970889

Fabrication of TiO2/EP super-hydrophobic thin film on filter paper surface.

PubMed

Gao, Zhengxin; Zhai, Xianglin; Liu, Feng; Zhang, Ming; Zang, Deli; Wang, Chengyu

2015-09-05

A composite filter paper with super-hydrophobicity was obtained by adhering micro/nano structure of amorphous titanium dioxide on the filter paper surface with modifying low surface energy material. By virtue of the coupling agent, which plays an important part in bonding amorphous titanium dioxide and epoxy resin, the structure of super-hydrophobic thin film on the filter paper surface is extremely stable. The microstructure of super-hydrophobic filter paper was characterized by scanning electron microscopy (SEM), the images showed that the as-prepared filter paper was covered with uniform amorphous titanium dioxide particles, generating a roughness structure on the filter paper surface. The super-hydrophobic performance of the filter paper was characterized by water contact angle measurements. The observations showed that the wettability of filter paper samples transformed from super-hydrophilicity to super-hydrophobicity with the water contact angle of 153 ± 1°. Some experiments were also designed to test the effect of water-oil separation and UV-resistant by the super-hydrophobic filter paper. The prepared super-hydrophobic filter paper worked efficiently and simply in water-oil separation as well as enduringly in anti-UV property after the experiments. This method offers an opportunity to the practical applications of the super-hydrophobic filter paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of Nano-Titanium Dioxide on Freshwater Algal Population Dynamics

PubMed Central

Kulacki, Konrad J.; Cardinale, Bradley J.

2012-01-01

To make predictions about the possible effects of nanomaterials across environments and taxa, toxicity testing must incorporate not only a variety of organisms and endpoints, but also an understanding of the mechanisms that underlie nanoparticle toxicity. Here, we report the results of a laboratory experiment in which we examined how titanium dioxide nanoparticles impact the population dynamics and production of biomass across a range of freshwater algae. We exposed 10 of the most common species of North American freshwater pelagic algae (phytoplankton) to five increasing concentrations of n-TiO2 (ranging from controls to 300 mg n-TiO2 L−1). We then examined the effects of n-TiO2 on the population growth rates and biomass production of each algal species over a period of 25 days. On average, increasing concentrations of n-TiO2 had no significant effects on algal growth rates (p = 0.376), even though there was considerable species-specific variation in responses. In contrast, exposure to n-TiO2 tended to increase maximum biomass achieved by species in culture (p = 0.06). Results suggest that titanium dioxide nanoparticles could influence certain aspects of population growth of freshwater phytoplankton, though effects are unlikely at environmentally relevant concentrations. PMID:23071735

Trace quantification of selected sulfonamides in aqueous media by implementation of a new dispersive solid-phase extraction method using a nanomagnetic titanium dioxide graphene-based sorbent and HPLC-UV.

PubMed

Izanloo, Maryam; Esrafili, Ali; Behbahani, Mohammad; Ghambarian, Mahnaz; Reza Sobhi, Hamid

2018-02-01

Herein, a new dispersive solid-phase extraction method using a nano magnetic titanium dioxide graphene-based sorbent in conjunction with high-performance liquid chromatography and ultraviolet detection was successfully developed. The method was proved to be simple, sensitive, and highly efficient for the trace quantification of sulfacetamide, sulfathiazole, sulfamethoxazole, and sulfadiazine in relatively large volume of aqueous media. Initially, the nano magnetic titanium dioxide graphene-based sorbent was successfully synthesized and subsequently characterized by scanning electron microscopy and X-ray diffraction. Then, the sorbent was used for the sorption and extraction of the selected sulfonamides mainly through π-π stacking hydrophobic interactions. Under the established conditions, the calibration curves were linear over the concentration range of 1-200 μg/L. The limit of quantification (precision of 20%, and accuracy of 80-120%) for the detection of each sulfonamide by the proposed method was 1.0 μg/L. To test the extraction efficiency, the method was applied to various fortified real water samples. The average relative recoveries obtained from the fortified samples varied between 90 and 108% with the relative standard deviations of 5.3-10.7%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanomaterial Case Studies: Nanoscale Titanium Dioxide in ...

EPA Pesticide Factsheets

EPA announced the availability of the final report, Nanomaterial Case Studies: Nanoscale Titanium Dioxide in Water Treatment and in Topical Sunscreen. This report is a starting point to determine what is known and what needs to be known about selected nanomaterials as part of a process to identify and prioritize research to inform future assessments of the potential ecological and health implications of these materials. Two specific applications of nanoscale titanium dioxide (nano-TiO2) are considered: (1) as an agent for removing arsenic from drinking water; and (2) as an active ingredient in topical sunscreen. These case studies are organized around a comprehensive environmental assessment (CEA) framework that combines a product life cycle perspective with the risk assessment paradigm. They are intended to help identify what may need to be known in order to conduct a comprehensive environmental assessment of the potential risks related to nano-TiO2. These “case studies” do not represent completed or even preliminary assessments, nor are they intended to serve as a basis for risk management decisions in the near term on these specific uses of nano TiO2. Rather, the intent is to use this document in developing the scientific and technical information needed for future assessment efforts.

Antibacterial effect of hydrogen peroxide-titanium dioxide suspensions in the decontamination of rough titanium surfaces.

PubMed

Wiedmer, David; Petersen, Fernanda Cristina; Lönn-Stensrud, Jessica; Tiainen, Hanna

2017-07-01

The chemical decontamination of infected dental implants is essential for the successful treatment of peri-implantitis. The aim of this study was to assess the antibacterial effect of a hydrogen peroxide-titanium dioxide (H 2 O 2 -TiO 2 ) suspension against Staphylococcus epidermidis biofilms. Titanium (Ti) coins were inoculated with a bioluminescent S. epidermidis strain for 8 h and subsequently exposed to H 2 O 2 with and without TiO 2 nanoparticles or chlorhexidine (CHX). Bacterial regrowth, bacterial load and viability after decontamination were analyzed by continuous luminescence monitoring, live/dead staining and scanning electron microscopy. Bacterial regrowth was delayed on surfaces treated with H 2 O 2 -TiO 2 compared to H 2 O 2 . H 2 O 2 -based treatments resulted in a lower bacterial load compared to CHX. Few viable bacteria were found on surfaces treated with H 2 O 2 and H 2 O 2 -TiO 2 , which contrasted with a uniform layer of dead bacteria for surfaces treated with CHX. H 2 O 2 -TiO 2 suspensions could therefore be considered an alternative approach in the decontamination of dental implants.

Sabatier Catalyst Poisoning Investigation

NASA Technical Reports Server (NTRS)

Nallette, Tim; Perry, Jay; Abney, Morgan; Knox, Jim; Goldblatt, Loel

2013-01-01

The Carbon Dioxide Reduction Assembly (CRA) on the International Space Station (ISS) has been operational since 2010. The CRA uses a Sabatier reactor to produce water and methane by reaction of the metabolic CO2 scrubbed from the cabin air and the hydrogen byproduct from the water electrolysis system used for metabolic oxygen generation. Incorporating the CRA into the overall air revitalization system has facilitated life support system loop closure on the ISS reducing resupply logistics and thereby enhancing longer term missions. The CRA utilizes CO2 which has been adsorbed in a 5A molecular sieve within the Carbon Dioxide Removal Assembly, CDRA. There is a potential of compounds with molecular dimensions similar to, or less than CO2 to also be adsorbed. In this fashion trace contaminants may be concentrated within the CDRA and subsequently desorbed with the CO2 to the CRA. Currently, there is no provision to remove contaminants prior to entering the Sabatier catalyst bed. The risk associated with this is potential catalyst degradation due to trace organic contaminants in the CRA carbon dioxide feed acting as catalyst poisons. To better understand this risk, United Technologies Aerospace System (UTAS) has teamed with MSFC to investigate the impact of various trace contaminants on the CRA catalyst performance at relative ISS cabin air concentrations and at about 200/400 times of ISS concentrations, representative of the potential concentrating effect of the CDRA molecular sieve. This paper summarizes our initial assessment results.

Fischer-Tropsch Cobalt Catalyst Improvements with the Presence of TiO2, La2O3, and ZrO2 on an Alumina Support

NASA Technical Reports Server (NTRS)

Klettlinger, Jennifer Lindsey Suder

2012-01-01

The objective of this study was to evaluate the effect of titanium oxide, lanthanum oxide, and zirconium oxide on alumina supported cobalt catalysts. The hypothesis was that the presence of lanthanum oxide, titanium oxide, and zirconium oxide would reduce the interaction between cobalt and the alumina support. This was of interest because an optimized weakened interaction could lead to the most advantageous cobalt dispersion, particle size, and reducibility. The presence of these oxides on the support were investigated using a wide range of characterization techniques such as SEM, nitrogen adsorption, x-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed reduction after reduction (TPR-AR), and hydrogen chemisorptions/pulse reoxidation. Results indicated that both La2O3 and TiO2 doped supports facilitated the reduction of cobalt oxide species in reference to pure alumina supported cobalt catalysts, however further investigation is needed to determine the effect of ZrO2 on the reduction profile. Results showed an increased corrected cluster size for all three doped supported catalysts in comparison to their reference catalysts. The increase in reduction and an increase in the cluster size led to the conclusion that the support-metal interaction weakened by the addition of TiO2 and La2O3. It is also likely that the interaction decreased upon presence of ZrO2 on the alumina, but further research is necessary. Preliminary results have indicated that the alumina-supported catalysts with titanium oxide and lanthanum oxide present are of interest because of the weakened cobalt support interaction. These catalysts showed an increased extent of reduction, therefore more metallic cobalt is present on the support. However, whether or not there is more cobalt available to participate in the Fischer-Tropsch synthesis reaction (cobalt surface atoms) depends also on the cluster size. On one hand, increasing cluster size alone tends to decrease the active site density; on the other hand, by increasing the size of the cobalt clusters, there is less likelihood of forming oxidized cobalt complexes (cobalt aluminate) during Fischer-Tropsch synthesis. Thus, from the standpoint of stability, improving the extent of reduction while increasing the particle size slightly may be beneficial for maintaining the sites, even if there is a slight decrease in overall initial active site density.

Effects of the biosynthesis and signaling pathway of ecdysterone on silkworm (Bombyx mori) following exposure to titanium dioxide nanoparticles.

PubMed

Li, Fanchi; Gu, Zhiya; Wang, Binbin; Xie, Yi; Ma, Lie; Xu, Kaizun; Ni, Min; Zhang, Hua; Shen, Weide; Li, Bing

2014-08-01

Silkworm (Bombyx mori), a model Lepidoptera insect, is economically important. Its growth and development are regulated by endogenous hormones. During the process of transition from larvae to pupae, 20-hydroxyecdysone (20E) plays an important role. The recent surge in consumer products and applications using metallic nanoparticles has increased the possibility of human or ecosystem exposure due to their unintentional release into the environment. We investigated the effects of exposure to titanium dioxide nanoparticles (TiO2 NPs) on the action of 20E in B. mori. Titanium dioxide nanoparticle treatment shortened the molting duration by 8 hr and prolonged the molting peak period by 10 %. Solexa sequencing profiled the changes in gene expression in the brain of fifth-instar B. mori in response to TiO2NPS exposure for 72 hr, to address the effects on hormone metabolism and regulation. Thirty one genes were differentially expressed. The transcriptional levels of pi3k and P70S6K, which are involved in the target of the rapamycin (TOR) signaling pathway, were up-regulated. Transcriptional levels of four cytochrome P450 genes, which are involved in 20E biosynthesis, at different developmental stages (48, 96, 144, and 192 hr) at 5th instars of all displayed trends of increasing expression. Simultaneously, the ecdysterone receptors, also displayed increasing trends. The 20E titers at four developmental stages during the 5th instar were 1.26, 1.23, 1.72, and 2.16 fold higher, respectively, than the control group. These results indicate that feeding B. mori with TiO2 NPs stimulates 20E biosynthesis, shortens the developmental progression, and reduces the duration of molting. Thus, application of TiO2 NPs is of high significance for saving the labor force in sericulture, and our research provides a reference for the ecological problems in the field of Lepidoptera exposured to titanium dioxide nanoparticles.

Electron microscopic investigation and elemental analysis of titanium dioxide in sun lotion.

PubMed

Sysoltseva, M; Winterhalter, R; Wochnik, A S; Scheu, C; Fromme, H

2017-06-01

The objective of this research was to determine the size, shape and aggregation of titanium dioxide (TiO 2 ) particles which are used in sun lotion as UV-blocker. Overall, six sunscreens from various suppliers and two reference substances were analysed by electron microscopy (EM) techniques in combination with energy dispersive X-ray spectroscopy (EDS). Because of a high fat content in sun lotion, it was impossible to visualize the TiO 2 particles without previous EM sample preparation. Different defatting methods for TiO 2 from sun screens were tested. A novel sample preparation method was developed which allowed the characterization of TiO 2 particles with the help of EM and EDS. Aggregates of titanium dioxide with the size of primary particles varying between 15 and 40 nm were observed only in five products. In the sun lotion with the highest SPF, only few small aggregates were found. In the sun screen with the lowest SPF, the largest aggregates of TiO 2 particles were detected with sizes up to 1.6 μm. In one of the sun lotions, neither TiO 2 nor ZnO was found in spite of the labelling. Instead, approx. 500 nm large diamond-shaped particles were observed. These particles are composed of an organic material as only carbon was detected by EDS. A novel defatting method for sample preparation of titanium dioxide nanoparticles used in sun cosmetics was developed. This method was applied to six different sun lotions with SPF between 30 and 50+. TiO 2 particles were found in only five sunscreens. The sizes of the primary particles were below 100 nm and, according to the EU Cosmetic Regulation, have to be listed on the package with the term 'nano'. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Solar hydrogen and solar electricity using mesoporous materials

NASA Astrophysics Data System (ADS)

Mahoney, Luther

The development of cost-effective materials for effective utilization of solar energy is a major challenge for solving the energy problems that face the world. This thesis work relates to the development of mesoporous materials for solar energy applications in the areas of photocatalytic water splitting and the generation of electricity. Mesoporous materials were employed throughout the studies because of their favorable physico-chemical properties such as high surface areas and large porosities. The first project was related to the use of a cubic periodic mesoporous material, MCM-48. The studies showed that chromium loading directly affected the phase of mesoporous silica formed. Furthermore, within the cubic MCM-48 structure, the loading of polychromate species determined the concentration of solar hydrogen produced. In an effort to determine the potential of mesoporous materials, titanium dioxide was prepared using the Evaporation-Induced Self-Assembly (EISA) synthetic method. The aging period directly determined the amount of various phases of titanium dioxide. This method was extended for the preparation of cobalt doped titanium dioxide for solar simulated hydrogen evolution. In another study, metal doped systems were synthesized using the EISA procedure and rhodamine B (RhB) dye sensitized and metal doped titania mesoporous materials were evaluated for visible light hydrogen evolution. The final study employed various mesoporous titanium dioxide materials for N719 dye sensitized solar cell (DSSC) materials for photovoltaic applications. The materials were extensively characterized using powder X-ray diffraction (XRD), nitrogen physisorption, diffuse reflectance spectroscopy (DRS), UV-Vis spectroscopy, Fourier-Transform-Infrared Spectroscopy (FT-IR), Raman spectroscopy, chemisorption, photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). In addition, photoelectrochemical measurements were completed using current-voltage (I-V) curves, external quantum efficiency (EQE) curves, electrochemical impedance spectroscopy (EIS), and transient spectroscopy. The thesis work presented provides a better understanding of the role of mesoporous materials for solar hydrogen and solar electricity production.

New method to synthesize mesoporous titania by photodegradation of surfactant template

NASA Astrophysics Data System (ADS)

Zi, Shamsuddin Chik; Chandren, Sheela; Yuan, Lai Sin; Razali, Rasidah; Ho, Chin Siong; Hartanto, Djoko; Indra Mahlia, Teuku Meurah; Nur, Hadi

2016-02-01

Mesoporous titania has been successfully synthesized by photodegradation removal of cetyltrimethylammonium bromide as the surfactant, after slow hydrolyzation of titanium(IV) isopropoxide. Fourier transform infrared spectra proved that photodegradation has successfully decreased the peak areas of the alkyl groups from the template. The nitrogen adsorption analysis showed that the pore size and the specific surface area of the mesoporous titania were 3.7 nm and 203 m2 g-1, respectively, proving the mesoporosity of the titania obtained with the existence of the interparticle mesoporosity which was confirmed by transmission electron microscopy. Based on X-ray diffraction results, the mesoporous titania obtained was in the form of crystalline anatase phase. Furthermore, results from the diffuse reflectance ultra violet-visible spectra showed that the composition of tetrahedral titanium(IV) was more than the octahedral titanium(IV). When the mesoporous titania obtained was used as a catalyst in the oxidation of styrene, an improvement in the conversion of styrene (38%) was observed when compared to those obtained using Degussa P25 TiO2 (14%) as the catalyst.

Electrochemical characterization of nano-sized Pd-based catalysts as cathode materials in direct methanol fuel cells.

PubMed

Choi, M; Han, C; Kim, I T; An, J C; Lee, J J; Lee, H K; Shim, J

2011-01-01

To improve the catalytic activity of palladium (Pd) as a cathode catalyst in direct methanol fuel cells (DMFCs), we prepared palladium-titanium oxide (Pd-TiO2) catalysts which the Pd and TiO2 nanoparticles were simultaneously impregnated on carbon. We selected Pd and TiO2 as catalytic materials because of their electrochemical stability in acid solution. The crystal structure and the loading amount of Pd and TiO2 on carbon were characterized by X-ray diffraction (XRD) and energy dispersive X-ray microanalysis (EDX). The electrochemical characterization of Pd-TiO2/C catalysts for the oxygen reduction reaction was carried out in half and single cell systems. The catalytic activities of the Pd-TiO2 catalysts were strongly influenced by the TiO2 content. In the single cell test, the Pd-TiO2 catalysts showed very comparable performance to the Pt catalyst.

Optical and morphological properties of sol gel derived titanium dioxide films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, A. B.; Sharma, S. K.; M, Vishwas

2015-08-28

Titanium oxide (Titania) thin films were synthesized on different substrates via the sol-gel dip-coating method using alkoxide solution. Some selected samples were also prepared with different percentage of Lead (Pb). The influence of Pb addition in precursor sol on the optical properties of titanium dioxide thin films was studied. The optical transmittance in the visible region has increased with increase in weight percentage of lead. The refractive index was slightly decreased with Pb addition. Crystallization of these coatings was achieved through thermal annealing at temperatures above 400 °C. The structural properties and surface morphology of the crystallized coatings were studiedmore » by Scanning Electron Microscopy. Increase in average grain size from 250 nm to 350 nm with increase in Pb concentration is observed. Films were appeared to more coarse with increase in Pb addition. An increase in Pb addition resulted increase in average roughness from 12 nm to 25 nm.« less

Chemical analysis of extracting transition metal oxides from polymetallic ore by sulphate process

NASA Astrophysics Data System (ADS)

Enkh-Uyanga, Otgon-Uul; Munkhtsetseg, Baatar; Urangoo, Urtnasan; Tserendulam, Enkhtur; Agiimaa, Davaadorj

2017-06-01

In this research work we attempt to improve the purity of polymetallic ores in Mongolia whilst developing practical applications of its refinement processes and this paper presents the results of chemical research of extracting transition metal titanium oxides, ferrous oxide and rare earth oxides from polymetallic ore. Thereby, chemical and mineral analysis of polymetallic ore is carried out basis of responses to the support process at various degrees of water whereas transition metal sulphates solubility differ. As a result of sulphate and resulphurization process we have extracted anatase with 62.5 percent titanium dioxide and brookite mineral with 89.6 percent of titanium dioxide as well as mineral with 83.8 percent of ferrous oxide hematite and rare earth oxides with 57.6 percent of cerium oxide. These oxides are identified under various conditions in the thermal processing. The morphology structure and chemical content compound of the mineral has been verified as a result of the XRF, XRD, SEM-EDX analysis.

Synthesis, characterization and application of doped electrolytic manganese dioxides

NASA Astrophysics Data System (ADS)

Jantscher, Wolfgang; Binder, Leo; Fiedler, Dirk A.; Andreaus, Reinhard; Kordesch, Karl

Electrolytic manganese dioxides (EMDs) were prepared on the 100 g scale by anodic deposition from acidic aqueous solutions of manganese sulfate. In situ doping with titanium ions was achieved by addition of tetra- n-butoxytitanium to the electrolytic bath. Samples were also doped ex situ by washing the products with aqueous barium hydroxide solution. The EMDs were characterized by electron microscopy studies and BET surface area determinations. Cyclic abrasive stripping voltammetry was successfully applied to evaluate the rechargeability of the newly synthesized undoped and doped EMDs in 9 M KOH. Relative discharge capacities at different depths of discharge (DOD) with respect to the first one-electron reduction of γ-MnO 2 are compared for different EMDs. At about 30% DOD, resulting relative discharge capacities show essentially the same trend as those measured in AA cells from about 10 to 20 discharge/charge cycles onwards. Accordingly, titanium-doped EMD was shown to exhibit superior charge retention and rechargeability when compared to the titanium-free samples.

Synthesis of nano-titanium dioxide by sol-gel route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaler, Vandana, E-mail: vandana.kaler@gmail.com; Duchaniya, R. K.; Pandel, U.

Nanosized titanium dioxide powder was synthesised via sol-gel route by hydrolysis of titanium tetraisopropoxide with ethanol and water mixture in high acidic medium. The synthesized nanopowder was further characterized by X-ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and Ultraviolet Visible Spectroscopy in order to determine size, morphology and crystalline structure of the material. The synthesis of nano-TiO{sub 2} powder in anatase phase was realized by XRD. The optical studies of nano-TiO{sub 2} powder was carried out by UV-Vis spectroscopy and band gap was calculated as 3.5eV, The SEM results with EDAX confirmed that prepared nano-TiO{sub 2} particles weremore » in nanometer range with irregular morphology. The FTIR analysis showed that only desired functional groups were present in sample. These nano-TiO{sub 2} particles have applications in solar cells, chemical sensors and paints, which are thrust areas these days.« less