Low-Temperature Reverse Microemulsion Synthesis, Characterization, and Photocatalytic Performance of Nanocrystalline Titanium Dioxide

Directory of Open Access Journals (Sweden)

Zhang Liu

2012-01-01

Full Text Available Nanocrystalline titanium dioxide (TiO2 was synthesized in microemulsions by using cetyltrimethylammonium bromide (CTAB as surfactant. In order to investigate the crystal transformation and photoactivity at low temperature, the as-prepared precipitates were aged at 65°C or calcined at various temperatures. Analyses using powder X-ray diffraction (XRD and Fourier transform infrared microscopy (FT-IR showed that precursors without aging or calcination were noncrystal and adsorbed by surfactant. After aging for 6 h, the amorphous TiO2 began to change into anatase. The obtained catalysts, which were synthesized in microemulsions with weight ratios of n-hexanol/CTAB/water as 6 : 3 : 1 and calcined at 500°C, presented the highest photocatalytic degradation rate on methyl orange (MO, while the catalysts, which were aged at 65°C for 90 h, also exhibited an outstanding photocatalytic performance and a little higher than that of the commercial titania photocatalyst Degussa P25.

Photocatalytic activity of titanium dioxide modified concrete materials - influence of utilizing recycled glass cullets as aggregates.

Science.gov (United States)

Chen, Jun; Poon, Chi-Sun

2009-08-01

Combining the use of photocatalysts with cementitious materials is an important development in the field of photocatalytic air pollution mitigation. This paper presents the results of a systematic study on assessing the effectiveness of pollutant degradation by concrete surface layers that incorporate a photocatalytic material - Titanium Dioxide. The photocatalytic activity of the concrete samples was determined by photocatalytic oxidation of nitric oxide (NO) in the laboratory. Recycled glass cullets, derived from crushed waste beverage bottles, were used to replace sand in preparing the concrete surface layers. Factors, which may affect the pollutant removal performance of the concrete layers including glass color, aggregate size and curing age, were investigated. The results show a significant enhancement of the photocatalytic activity due to the use of glass cullets as aggregates in the concrete layers. The samples fabricated with clear glass cullets exhibited threefold NO removal efficiency compared to the samples fabricated with river sand. The light transmittance property of glass was postulated to account for the efficiency improvement, which was confirmed by a separate simulation study. But the influence of the size of glass cullets was not evident. In addition, the photocatalytic activity of concrete surface layers decreased with curing age, showing a loss of 20% photocatalytic activity after 56-day curing.

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.

Science.gov (United States)

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.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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

Potential for photocatalytic degradation of the potassic diclofenac using scandium and silver modified titanium dioxide thin films

International Nuclear Information System (INIS)

Ciola, R.A.; Oliveira, C.T.; Lopes, S.A.; Cavalheiro, A.A.

2011-01-01

The potential for photocatalytic degradation of the potassic diclofenac drug was investigated using titanium dioxide thin films modified with two modifier types, scandium and silver, both prepared by Sol-Gel method. It was demonstrated by UVVis spectroscopy analysis of the solutions containing the drug, under UV-A light irradiation that the degradation efficiency of the titanium dioxide photocatalyst is dependent of the semiconductor nature and that the scandium accelerates the first step of the degradation when compared to the silver. This result seems to be related to the redox potential of the electron-hole pair, once the scandium modifying sample generates a p type semiconductor that reduces the band gap. The extra holes attract more strongly the chorine ion present in diclofenac and leading to the releasing more easily. However, after the first byproducts degradation the following steps are not facilitated, making the silver modifying more advantageous. (author)

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

International Nuclear Information System (INIS)

Huppmann, T.; Leonhardt, S.; Krampe, E.; Wintermantel, E.; Yatsenko, S.; Radovanovic, I.; Bastian, M.

2014-01-01

To obtain a polymer with antimicrobial properties for medical and sanitary applications nanoscale titanium dioxide (TiO 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 2 for antimicrobial efficacy is to deposit a thin TiO 2 coating on the surface. In contrast to the common way of applying a coating, TiO 2 particles were applied into the bulk polymer. With this design we want to ensure antimicrobial properties even after application of impact effects that could lead to surface defects. The filler material (Aeroxide® TiO 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 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

Photocatalytically active titanium dioxide nanopowders: Synthesis, photoactivity and magnetic separation

International Nuclear Information System (INIS)

Nikkanen, J-P; Heinonen, S; Saarivirta, E Huttunen; Honkanen, M; Levänen, E

2013-01-01

Two approaches were used to obtain nanocrystalline titanium dioxide (TiO 2 ) photocatalyst powders. Firstly, low-temperature synthesis method and secondly liquid flame spraying. The structural properties of the produced powders were determined with X-ray diffraction, transmission electron microscopy and nitrogen adsorption tests. The photocatalytic properties of the powders were studied with methylene blue (MB) discoloration tests. After discolorations tests, TiO 2 was coagulated with magnetite particles using FeCl 3 ·6 H 2 O at a fixed pH value. Magnetic separation of coagulated TiO 2 and magnetite was carried out by a permanent magnet. The obtained results showed that the particle size of the powders synthesized at low-temperature was very small and the specific surface area high. The phase content of the powder was also shown to depend greatly on the acidity of the synthesis solution. Powder synthesized by liquid flame spraying was mixture of anatase and rutile phases with essentially larger particle size and lower specific surface area than those of low-temperature synthesized powders. The MB discoloration test showed that photocatalytic activity depends on the phase structure as well as the specific surface area of the synthesized TiO 2 powder. The magnetic separation of TiO 2 –magnetite coagulate from solution proved to be efficient around pH:8

Photocatalytic effects of titanium dioxide nanoparticles on aquatic organisms—Current knowledge and suggestions for future research

Energy Technology Data Exchange (ETDEWEB)

Haynes, Vena N., E-mail: vena.haynes@uconn.edu [University of Connecticut, Department of Marine Sciences, 1080 Shennecossett Road, Groton, CT 06340 (United States); Ward, J. Evan, E-mail: evan.ward@uconn.edu [University of Connecticut, Department of Marine Sciences, 1080 Shennecossett Road, Groton, CT 06340 (United States); Russell, Brandon J., E-mail: brandon.russell@uconn.edu [University of Connecticut, Department of Marine Sciences, 1080 Shennecossett Road, Groton, CT 06340 (United States); Agrios, Alexander G., E-mail: agrios@engr.uconn.edu [University of Connecticut, Department of Civil & Environmental Engineering, 261 Glenbrook Road Unit 3037, Storrs, CT 06269 (United States)

2017-04-15

Highlights: • Ecotoxicological approaches are needed to predict effects of photoactive nanomaterials. • Research on effects of photoactive nanomaterials must include defined light fields. • Light fields must be appropriate for depth, latitude, season and water properties. • Physicochemical properties of water can alter light fields and photoreactivity. - Abstract: 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{sub 2} nanoparticles on aquatic organisms, discuss the limitations of these studies, and outline environmentally-relevant factors that need to be considered in future experiments.

Investigation of photocatalytic activity of titanium dioxide coating deposited on aluminium alloy substrate by plasma technique

DEFF Research Database (Denmark)

Daviðsdóttir, Svava; Soyama, Juliano; Dirscherl, Kai

2011-01-01

. Literature consists of large number of publications on titanium dioxide coating for self-cleaning applications, with glass as the main substrate. Only little work is available on TiO2 coating of metallic alloys used for engineering applications. Engineering materials, such as light-weight aluminium and steel...... have wide spread technological applications, where a combination of self-cleaning properties has a huge business potential. The results presented in this paper demonstrate superior photocatalytic properties of TiO2 coated aluminium compared to nano-scale TiO2 coating on glass substrate. The thickness...

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

Energy Technology Data Exchange (ETDEWEB)

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; Wintermantel, E., E-mail: wintermantel@tum.de [Institute of Medical and Polymer Engineering, Technische Universität München (Germany); Yatsenko, S., E-mail: s.yatsenko@skz.de; Radovanovic, I., E-mail: i.radovanovic@skz.de, E-mail: m.bastian@skz.de; Bastian, M., E-mail: i.radovanovic@skz.de, E-mail: m.bastian@skz.de [SKZ- German Plastics Center, Würzburg (Germany)

2014-05-15

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 that 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.

Enhanced photoactivity of graphene/titanium dioxide nanotubes for removal of Acetaminophen

International Nuclear Information System (INIS)

Tao, Hong; Liang, Xiao; Zhang, Qian; Chang, Chang-Tang

2015-01-01

Highlights: • TiO 2 and graphite oxide were used as precursors of titanium dioxide nanotubes and graphene respectively. Titanium dioxide nanotube and graphene (GR-TNT) nanocomposites were synthesized through a simple hydrothermal method. • And its application to removal acetaminophen, degradation efficiency is more than 96%. • The photocatalytic degradation results indicated that the sample with 5% GO in GR-TNT nanocomposites for 3 h had the highest degradation rate. • The degradation intermediates of acetaminophen by the composites were invested by GC-MS and the possible pathways were invested. - Abstract: Acetaminophen is commonly used as an antipyretic or analgesics agent and poses threat to human health. In this research, TiO 2 and graphite oxide were used as precursors of titanium dioxide nanotubes and graphene respectively. Titanium dioxide nanotube and graphene (GR-TNT) nanocomposites were synthesized through a hydrothermal method. FT-IR, UV-Vis, XRD, and TGA were used to characterize the catalysts. The acetaminophen degradation rate can reach up to 96% under UV light irradiation for 3 h and with the 5% GR-TNT dosage of 0.1 g L −1 . Further experiments were done to probe the mechanism of the photocatalytic reaction catalyzed by the GR-TNT composite. EDTA (hole scavengers) and t-BuOH (radical scavengers) were used to detect the main active oxidative species in the system. The results showed that the holes are the main oxidation species in the photocatalytic process. This study provides a new prospect for acetaminophen degradation by using high efficiency catalysts

Determining the efficiency of ZSM-5 zeolite impregnated with nanoparticles of titanium dioxide in the photocatalytic removal of styrene vapors

Directory of Open Access Journals (Sweden)

Mojtaba Nakhaei pour

2017-03-01

Full Text Available Introduction: Styrene monomer is a volatile organic compound that has many applications particularly in plastic, rubber and paint industries. According to the harmful effects of these compounds on human and environment, reducing and controling of them seem necessary. Therefore, in this study removal of styrene was investigated using photocatalytic process of titanium dioxide nanoparticles stabilized on ZSM-5. Methods: After stabilization of titanium dioxide nanoparticles on ZSM-5 zeolite, BET, SEM and XRD analysis were used to determine the characteristics of nanoparticles. Experiments were conducted at ambient temperature in laboratory scale. Concentration of produced styrene in the experiments was 50 and 300 ppm, and input flow rate was 1 l/min. Results: images and spectra obtained through XRD and SEM-EDAX showed that  nano-catalysts are well- stabilized. The results showed that by increasing of input concentration of styrene from 50 to 300 ppm, photocatalytic removal efficiency are reduced. Also, adsorption capacity of the catalyst bed in concentrations of 50 and 300 ppm was calculated 16.3 and19.4 mg/gr of adsorbent respectively. Conclusion: The results show that the use of hybrid bed can increase the removal efficiency of contaminants. And due to low cost of application of these systems compared to conventional methods, it is recommended that more comprehensive studies to be done regarding the optimization of the parameters affecting the process of photocatalytic removal.

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

Energy Technology Data Exchange (ETDEWEB)

Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long, E-mail: jianglong@scu.edu.cn; Dan, Yi, E-mail: danyichenweiwei@163.com

2015-07-01

Graphical abstract: - Highlights: • The study provides an easy and convenient method to fabricate films, which will give guidance for the preparation of three-dimensional materials. • The PPy/PVA–TiO{sub 2} films can keep better photo-catalytic activities both under UV and visible light irradiation when compared with TiO{sub 2} film. • There exist electron transfers between PPy/PVA and TiO{sub 2}. - Abstract: Polypyrrole/polyvinyl alcohol–titanium dioxide (PPy/PVA–TiO{sub 2}) composite films used as photo-catalysts were fabricated by combining TiO{sub 2} 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 TiO{sub 2} 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–TiO{sub 2} composite films show better photo-catalytic properties than TiO{sub 2} 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–TiO{sub 2} composite film was investigated and the results show that

Nano titanium dioxide photocatalytic protein tyrosine nitration: A potential hazard of TiO2 on skin

International Nuclear Information System (INIS)

Lu, Naihao; Zhu Zhening; Zhao Xuqi; Tao Ran; Yang Xiangliang; Gao Zhonghong

2008-01-01

Protein tyrosine nitration is a prevalent post-translational modification which occurs as a result of oxidative and nitrative stress, it may be directly involved in the onset and/or progression of diseases. Considering the existence of nano titanium dioxide (TiO 2 ) in environment and sunscreen products along with the high content of nitrite in sweat, the UV-exposed skin may be a significant target for the photosensitized damage. In this paper, tyrosine nitration of bovine serum albumin (BSA) was initiated in the UV-irradiated reaction mixture containing 0.2-3.0 mg/ml of three commercially nano TiO 2 products and 0.25-1.0 mM NO 2 - . It was found that anatase TiO 2 and Degussa P25 TiO 2 showed prominent photocatalytic activity on promoting the formation of protein tyrosine nitration, and the optimum condition for the reaction was around physiological pH. Meanwhile, the photocatalytic effect of rutile on protein tyrosine nitration was subtle. The potential physiological significance of nano TiO 2 -photocatalytic protein nitration was also demonstrated in mouse skin homogenate. Although the relationship between photocatalytic protein tyrosine nitration and chronic cutaneous diseases needs further study, the toxicity of nano TiO 2 to the skin disease should be paid more attention in the production and utilization process

Black Titanium Dioxide Nanomaterials in Photocatalysis

Directory of Open Access Journals (Sweden)

Xiaodong Yan

2017-01-01

Full Text Available Titanium dioxide (TiO2 nanomaterials are widely considered to be state-of-the-art photocatalysts for environmental protection and energy conversion. However, the low photocatalytic efficiency caused by large bandgap and rapid recombination of photo-excited electrons and holes is a challenging issue that needs to be settled for their practical applications. Structure engineering has been demonstrated to be a highly promising approach to engineer the optical and electronic properties of the existing materials or even endow them with unexpected properties. Surface structure engineering has witnessed the breakthrough in increasing the photocatalytic efficiency of TiO2 nanomaterials by creating a defect-rich or amorphous surface layer with black color and extension of optical absorption to the whole visible spectrum, along with markedly enhanced photocatalytic activities. In this review, the recent progress in the development of black TiO2 nanomaterials is reviewed to gain a better understanding of the structure-property relationship with the consideration of preparation methods and to project new insights into the future development of black TiO2 nanomaterials in photocatalytic applications.

Inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation.

Science.gov (United States)

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...

Titanium dioxide nanomaterials for photocatalysis

International Nuclear Information System (INIS)

Liu, Yan; Li, Zhe; Green, Michael; Just, Michael; Chen, Xiaobo; Li, Yang Yang

2017-01-01

Titanium dioxide (TiO 2 ) has been long regarded as one of the more promising photocatalysts to remove environmental pollution and to generate hydrogen from water under sunlight irradiation via photocatalysis. TiO 2 is environmentally benign and thus is considered a ‘green’ catalyst. In this review we present a short introduction to the physical and electronic properties of TiO 2 , its photocatalytic mechanisms, and some recent examples of various TiO 2 materials used for photocatalysis; these examples include 0, 1, 2, 3D, faceted, defected, composited, and hydrogenated TiO 2 materials. (topical review)

Stannic Oxide-Titanium Dioxide Coupled Semiconductor Photocatalyst Loaded with Polyaniline for Enhanced Photocatalytic Oxidation of 1-Octene

Directory of Open Access Journals (Sweden)

Hadi Nur

2007-01-01

Full Text Available Stannic oxide-titanium dioxide (SnO2–TiO2 coupled semiconductor photocatalyst loaded with polyaniline (PANI, a conducting polymer, possesses a high photocatalytic activity in oxidation of 1-octene to 1,2-epoxyoctane with aqueous hydrogen peroxide. The photocatalyst was prepared by impregnation of SnO2 and followed by attachment of PANI onto a TiO2 powder to give sample PANI-SnO2–TiO2. The electrical conductivity of the system becomes high in the presence of PANI. Enhanced photocatalytic activity was observed in the case of PANI-SnO2–TiO2 compared to PANI-TiO2, SnO2–TiO2, and TiO2. A higher photocatalytic activity in the oxidation of 1-octene on PANI-SnO2–TiO2 than SnO2–TiO2, PANI-TiO2, and TiO2 can be considered as an evidence of enhanced charge separation of PANI-SnO2–TiO2 photocatalyst as confirmed by photoluminescence spectroscopy. It suggests that photoinjected electrons are tunneled from TiO2 to SnO2 and then to PANI in order to allow wider separation of excited carriers.

Facile synthesis of silicon carbide-titanium dioxide semiconducting nanocomposite using pulsed laser ablation technique and its performance in photovoltaic dye sensitized solar cell and photocatalytic water purification

Energy Technology Data Exchange (ETDEWEB)

Gondal, M.A., E-mail: magondal@kfupm.edu.sa [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Ilyas, A.M. [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Baig, Umair [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Center of Excellence for Scientific Research Collaboration with MIT, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

2016-08-15

Highlights: • SiC–TiO{sub 2} semiconducting nanocomposites synthesized by nanosecond PLAL technique. • Synthesized nanocomposites were morphologically and optically characterized. • Nanocomposites were applied for the photocatalytic degradation of toxic organic dye. • Photovoltaic performance was investigated in dye sensitized solar cell. - Abstract: Separation of photo-generated charge carriers (electron and holes) is a major approach to improve the photovoltaic and photocatalytic performance of metal oxide semiconductors. For harsh environment like high temperature applications, ceramic like silicon carbide is very prominent. In this work, 10%, 20% and 40% by weight of pre-oxidized silicon carbide was coupled with titanium dioxide (TiO{sub 2}) to form nanocomposite semiconductor via elegant pulsed laser ablation in liquid technique using second harmonic 532 nm wavelength of neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. In addition, the effect of silicon carbide concentration on the performance of silicon carbide-titanium dioxide nanocomposite as photo-anode in dye sensitized solar cell and as photocatalyst in photodegradation of methyl orange dye in water was also studied. The result obtained shows that photo-conversion efficiency of the dye sensitized solar cell was improved from 0.6% to 1.65% and the percentage of methyl orange dye removed was enhanced from 22% to 77% at 24 min under ultraviolet–visible solar spectrum in the nanocomposite with 10% weight of silicon carbide. This remarkable performance enhancement could be due to the improvement in electron transfer phenomenon by the presence of silicon carbide on titanium dioxide.

Classification of titanium dioxide

International Nuclear Information System (INIS)

Macias B, L.R.; Garcia C, R.M.; Maya M, M.E.; Ita T, A. De; Palacios G, J.

2002-01-01

In this work the X-ray diffraction (XRD), Scanning Electron Microscopy (Sem) and the X-ray Dispersive Energy Spectroscopy techniques are used with the purpose to achieve a complete identification of phases and mixture of phases of a crystalline material as titanium dioxide. The problem for solving consists of being able to distinguish a sample of titanium dioxide being different than a titanium dioxide pigment. A standard sample of titanium dioxide with NIST certificate is used, which indicates a purity of 99.74% for the TiO 2 . The following way is recommended to proceed: a)To make an analysis by means of X-ray diffraction technique to the sample of titanium dioxide pigment and on the standard of titanium dioxide waiting not find differences. b) To make a chemical analysis by the X-ray Dispersive Energy Spectroscopy via in a microscope, taking advantage of the high vacuum since it is oxygen which is analysed and if it is concluded that the aluminium oxide appears in a greater proportion to 1% it is established that is a titanium dioxide pigment, but if it is lesser then it will be only titanium dioxide. This type of analysis is an application of the nuclear techniques useful for the tariff classification of merchandise which is considered as of difficult recognition. (Author)

Photocatalytic oxidation of acetaminophen using carbon self-doped titanium dioxide

Directory of Open Access Journals (Sweden)

Mark Daniel G. de Luna

2016-07-01

Full Text Available A new carbon self-doped (C-doped TiO2 photocatalyst was synthesized by sol–gel method, in which titanium butoxide was utilized because of its dual functions as a titanium precursor and a carbon source. The effects of calcination temperature from 200 to 600 °C on the photocatalytic activity towards acetaminophen (ACT, which was used as a model persistent organic pollutant under visible light were examined. The effects of temperature on the structure and physicochemical properties of the C-doped TiO2 were also investigated by X-ray diffraction, BET measurement, X-ray photoelectron spectroscopy, and scanning electron microscopy. The specific surface area of the as-doped TiO2 declined as the crystal size increased with increasing calcination temperature. Only amorphous TiO2 was present at 200 °C, while an anatase phase was observed between 300 and 500 °C. Both anatase and rutile phases were observed at 600 °C. Photocatalytic activity increased as the calcination temperature initially increased from 200 to 300 °C but it decreased as the calcination temperature further increased from 400 to 600 °C. The highest ACT removal of 94% with an apparent rate constant of 5.0 × 10−3 min−1 was achieved using the new doped TiO2 calcined at 300 °C, which had an atomic composition of 31.6% Ti2p3, 50.3% O1s and 18.2% C1s.

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

Science.gov (United States)

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

Immobilization of nanoparticle titanium dioxide membrane on polyamide fabric by low temperature hydrothermal method

International Nuclear Information System (INIS)

Zhang Hui; Yang Lu

2012-01-01

A thin layer of nanoparticle titanium dioxide was immobilized on polyamide 6 (PA6) fiber using titanium sulfate and urea at low temperature hydrothermal condition. The titanium dioxide loaded fabric was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and thermal gravimetry techniques. The optical and mechanical properties, water absorption and degradation of methylene blue dye under ultraviolet (UV) irradiation of the PA6 fabric before and after treatments were also examined. It was found that when PA6 fabric was treated in titanium sulfate and urea aqueous solution, anatase nanocrystalline titanium dioxide was synthesized and simultaneously adhered onto the fiber surface. The average crystal size of titanium dioxide nanoparticles was about 13.2 nm. The thermal behavior of PA6 fiber distinctly changed and the onset decomposition temperature decreased. As compared with the untreated fabric, the protection against UV radiation was improved. The water absorbency increased slightly. As the fabric dimensions were reduced in warp and weft directions, the breaking load and tensile strain increased to some extent. The titanium dioxide coated fabric could degradate methylene blue dye under UV irradiation. - Highlights: ► We employed a method to immobilize TiO 2 nanoparticle on polyamide fiber. ► We fabricated the TiO 2 -coated polyamide fabric with the photocatalytic activity. ► The modification method may be suitable for the potential applications.

Nitrogen doping in atomic layer deposition grown titanium dioxide films by using ammonium hydroxide

Energy Technology Data Exchange (ETDEWEB)

Kaeaeriaeinen, M.-L., E-mail: marja-leena.kaariainen@lut.fi; Cameron, D.C.

2012-12-30

Titanium dioxide films have been created by atomic layer deposition using titanium chloride as the metal source and a solution of ammonium hydroxide in water as oxidant. Ammonium hydroxide has been used as a source of nitrogen for doping and three thickness series have been deposited at 350 Degree-Sign C. A 15 nm anatase dominated film was found to possess the highest photocatalytic activity in all film series. Furthermore almost three times better photocatalytic activity was discovered in the doped series compared to undoped films. The doped films also had lower resistivity. The results from X-ray photoemission spectroscopy showed evidence for interstitial nitrogen in the titanium dioxide structure. Besides, there was a minor red shift observable in the thickest samples. In addition the film conductivity was discovered to increase with the feeding pressure of ammonium hydroxide in the oxidant precursor. This may indicate that nitrogen doping has caused the decrease in the resistivity and therefore has an impact as an enhanced photocatalytic activity. The hot probe test showed that all the anatase or anatase dominant films were p-type and all the rutile dominant films were n-type. The best photocatalytic activity was shown by anatase-dominant films containing a small amount of rutile. It may be that p-n-junctions are formed between p-type anatase and n-type rutile which cause carrier separation and slow down the recombination rate. The combination of nitrogen doping and p-n junction formation results in superior photocatalytic performance. - Highlights: Black-Right-Pointing-Pointer We found all N-doped and undoped anatase dominating films p-type. Black-Right-Pointing-Pointer We found all N-doped and undoped rutile dominating films n-type. Black-Right-Pointing-Pointer We propose that p-n junctions are formed in anatase-rutile mixture films. Black-Right-Pointing-Pointer We found that low level N-doping has increased TiO{sub 2} conductivity. Black

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

Science.gov (United States)

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.

40 CFR 180.1195 - Titanium dioxide.

Science.gov (United States)

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...

Direct generation of titanium dioxide nanoparticles dispersion under supercritical conditions for photocatalytic active thermoplastic surfaces for microbiological inactivation

International Nuclear Information System (INIS)

Zydziak, Nicolas; Zanin, Maria-Helena Ambrosio; Trick, Iris; Hübner, Christof

2015-01-01

Thermoplastic poly(propylene) (PP) and acrylonitrile-butadiene-styrene (ABS) surfaces were coated with silica based films via the sol–gel process, containing titanium dioxide (TiO 2 ) as photocatalyst. TiO 2 was previously synthesized via sol–gel and treated under supercritical conditions in water dispersions. The characterization of the TiO 2 dispersions was performed via disc centrifuge to determine the particle size and via Raman spectroscopy and X-Ray Diffraction (XRD) to characterize the crystallinity of TiO 2 . The synthesized TiO 2 dispersions and commercially available TiO 2 particles were incorporated in silica based films which were synthesized under acidic or basic conditions, leading to dense or porous films respectively. The morphology of the films was characterized via Scanning Electron Microscopy (SEM). The incorporation of synthesized TiO 2 in the coating led to photocatalytically more active thermoplastic surfaces than films formulated with commercially available TiO 2 as determined via dye discoloration test. A microbiological test performed with Sarcina lutea confirmed this result and showed an inactivation factor of 6 (99.9999%) after 24 h UV irradiation, for synthesized TiO 2 incorporated in acidic formulated silica layer on ABS surfaces. - Highlights: • We report about photocatalytic layers formulated on thermoplastic surfaces. • We synthesized silica layer and TiO 2 via sol–gel and supercritical treatment. • Amorphous, crystalline and commercial dispersions were generated and characterized. • The morphology of dense and porous photocatalytic layers is observed via SEM. • Discoloration and microbiological tests correlate activity and surface morphology

21 CFR 73.2575 - Titanium dioxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and... 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...

Exfoliated graphite/titanium dioxide nanocomposites for photodegradation of eosin yellow

Science.gov (United States)

Ndlovu, Thabile; Kuvarega, Alex T.; Arotiba, Omotayo A.; Sampath, Srinivasan; Krause, Rui W.; Mamba, Bhekie B.

2014-05-01

An improved photocatalyst consisting of a nanocomposite of exfoliated graphite and titanium dioxide (EG-TiO2) was prepared. SEM and TEM micrographs showed that the spherical TiO2 nanoparticles were evenly distributed on the surface of the EG sheets. A four times photocatalytic enhancement was observed for this floating nanocomposite compared to TiO2 and EG alone for the degradation of eosin yellow. For all the materials, the reactions followed first order kinetics where for EG-TiO2, the rate constant was much higher than for EG and TiO2 under visible light irradiation. The enhanced photocatalytic activity of EG-TiO2 was ascribed to the capability of graphitic layers to accept and transport electrons from the excited TiO2, promoting charge separation. This indicates that carbon, a cheap and abundant material, can be a good candidate as an electron attracting reservoir for photocatalytic organic pollutant degradation.

21 CFR 73.1575 - Titanium dioxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.1575 Section 73.1575 Food and... 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...

21 CFR 73.575 - Titanium dioxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.575 Section 73.575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive titanium dioxide is synthetically prepared TiO2, free from admixture with other substances. (2) Color...

21 CFR 73.3126 - Titanium dioxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891, shall...

Preliminary study towards photoactivity enhancement using a biocompatible titanium dioxide/carbon nanotubes composite

International Nuclear Information System (INIS)

Cendrowski, Krzysztof; Jedrzejczak, Malgorzata; Peruzynska, Magdalena; Dybus, Andrzej; Drozdzik, Marek; Mijowska, Ewa

2014-01-01

Graphical abstract: Scheme demonstrating the experimental steps toward the formation of titania/multiwalled carbon nanotubes (TiO 2 -MWCNTs) from multiwalled carbon nanotubes (MWCNT). - Highlights: • Easy and efficient method of impregnation carbon nanotubes with titania. • High photoactivity. • Correlation between the interaction of carbon nanotubes with titania on the photocatalytic properties. • High biocompatibility of the nanotubes. - Abstract: Recent research is focused on the enhancement in photoactivity of titanium dioxide/carbon nanotubes through formation of novel nanocomposites that exhibit a high specific surface area, remarkable electron transfer and biocompatibility. Here, we explore a new synthesis route in the system composed of nanocrystalline titanium dioxide supported on external walls and inner space of multiwalled carbon nanotubes (MWCNT). The advantages of this method are: its simplicity, direct fusion of titanium dioxide particles on the carbon material, and formation of chemical bond Ti–O–C between TiO 2 and MWCNT. Photocatalytic performance of this system has been compared to a commercial catalyst (Degussa P25) in a model reaction of phenol decomposition in/under UV light. The efficiency of the process increased by the factor of 2.5 when the TiO 2 –MWCNT photocatalyst was utilized. Further, the photoactive nanocomposite was analysed towards its biocompatibility in order to establish a safe dose of the catalyst. Its influence on the cells viability was studied on mouse fibroblasts and human liver tissue cells, in the range from 0 to 100 μg/mL. This has revealed that the composite in concentrations up to 25 μg/mL exerted low toxicity, which allowed for finding a compromise between the highest safe dose and acceptable photoactivity of the catalyst

Optimizing the photocatalytic properties and the synergistic effects of graphene and nano titanium dioxide immobilized on cotton fabric

International Nuclear Information System (INIS)

Karimi, Loghman; Yazdanshenas, Mohammad Esmail; Khajavi, Ramin; Rashidi, Abosaeed; Mirjalili, Mohammad

2015-01-01

Graphical abstract: - Highlights: • Producing superior photo-active cotton fabric using graphene/titanium dioxide nanocomposite. • Optimizing processing conditions using response surface methodology. • Obtaining significant photo-activity properties on cotton fabric by this method under sun irradiation. • Possessing excellent antimicrobial activity with low cytotoxicity on human fibroblasts. - Abstract: A new facile route based on cotton fabric coated with graphene/titanium dioxide nanocomposite is reported to produce photo-active cellulose textiles. A thin layer of graphene oxide has been produced on cotton fabrics by a dip-dry process. The graphene oxide-coated cotton fabrics were then immersed in titanium trichloride aqueous solution to yield a fabric coated with graphene/titanium dioxide nanocomposite. The photo-activity efficiency of the coated fabrics was tested by degradation of methylene blue in aqueous solution under UV and sunlight irradiations. To obtain the optimum condition, the response surface methodology (RSM) through the central composite design was applied and the role of both graphene oxide and titanium trichloride concentrations on photo-activity efficiency was investigated. The physicochemical properties of the prepared samples has been characterized by a series of techniques, including Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The effect of the application of graphene/titanium dioxide nanocomposite on the physical properties of the cotton fabric, such as tensile strength, bending rigidity and crease recovery angle has been analyzed. Other characteristics of treated fabrics such as antibacterial, antifungal and cytotoxicity were also investigated. Cotton fabric coated with optimum concentrations of graphene oxide and titanium trichloride obtained significant photo-activity efficiency under UV and sunlight irradiations. Moreover, the graphene/titanium

Direct generation of titanium dioxide nanoparticles dispersion under supercritical conditions for photocatalytic active thermoplastic surfaces for microbiological inactivation

Energy Technology Data Exchange (ETDEWEB)

Zydziak, Nicolas, E-mail: nicolas.zydziak@kit.edu [Polymer Engineering Department, Fraunhofer Institute of Chemical Technology, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal (Germany); Zanin, Maria-Helena Ambrosio [Laboratory of Chemical Processes and Particle Technology Bionanomanufacturing, Institute for Technological Research of the State of São Paulo – IPT, Av. Prof. Almeida Prado 532, Cidade Universitária, CEP 05508-901 São Paulo, SP (Brazil); Trick, Iris [Environmental Biotechnology and Bioprocess Engineering Department, Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstrasse 12, 70569 Stuttgart (Germany); Hübner, Christof [Polymer Engineering Department, Fraunhofer Institute of Chemical Technology, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal (Germany)

2015-03-01

Thermoplastic poly(propylene) (PP) and acrylonitrile-butadiene-styrene (ABS) surfaces were coated with silica based films via the sol–gel process, containing titanium dioxide (TiO{sub 2}) as photocatalyst. TiO{sub 2} was previously synthesized via sol–gel and treated under supercritical conditions in water dispersions. The characterization of the TiO{sub 2} dispersions was performed via disc centrifuge to determine the particle size and via Raman spectroscopy and X-Ray Diffraction (XRD) to characterize the crystallinity of TiO{sub 2}. The synthesized TiO{sub 2} dispersions and commercially available TiO{sub 2} particles were incorporated in silica based films which were synthesized under acidic or basic conditions, leading to dense or porous films respectively. The morphology of the films was characterized via Scanning Electron Microscopy (SEM). The incorporation of synthesized TiO{sub 2} in the coating led to photocatalytically more active thermoplastic surfaces than films formulated with commercially available TiO{sub 2} as determined via dye discoloration test. A microbiological test performed with Sarcina lutea confirmed this result and showed an inactivation factor of 6 (99.9999%) after 24 h UV irradiation, for synthesized TiO{sub 2} incorporated in acidic formulated silica layer on ABS surfaces. - Highlights: • We report about photocatalytic layers formulated on thermoplastic surfaces. • We synthesized silica layer and TiO{sub 2} via sol–gel and supercritical treatment. • Amorphous, crystalline and commercial dispersions were generated and characterized. • The morphology of dense and porous photocatalytic layers is observed via SEM. • Discoloration and microbiological tests correlate activity and surface morphology.

Biological characterization of coatings based on titanium dioxide doped with metallic elements for antimicrobial applications

OpenAIRE

Silva, Isabel Carina Simões da

2013-01-01

Dissertação de mestrado em Biofísica e Bionanossistemas The use of semiconductors for processes of self-­‐cleaning, air and water depollution as well as surface disinfection has triggered a great interest in the scientific community. One of the most used semiconductor materials is titanium dioxide (TiO2) due to their large photocatalytic effect, higher oxidati...

COMBINED BIOLOGICAL-PHOTOCATALYTIC TREATMENT FOR THE MINERALIZATION OF A MIXTURE OF CHLOROPHENOLS IN AN ELECTROLYTE-CONTAINING MODEL WATER AND SPONTANEOUS SEDIMENTATION OF TITANIUM DIOXIDE

Directory of Open Access Journals (Sweden)

Dhanus Suryaman

2010-06-01

Full Text Available To shorten the biological treating time and to examine the effect of electrolytes in a model water on the photocatalytic treatment, the combined biological-photocatalytic treatment was evaluated for removal of a mixture (total: 100 mg L-1, each: 25 mg L-1 of 2-chlorophenol (2-CP, 2,4-dichlorophenol (2,4-DCP, 2,4,5-trichlorophenol (2,4,5-TCP, and pentachlorophenol (PCP in tap water. The mineralization of the four phenols was performed by a flow (biological treatment-circulative flow (photocatalytic treatment operation under black light and sunlight irradiations. After a large portion of biodegradable 2-CP and 2,4-DCP, and around half amount of slightly biodegradable 2,4,5-TCP were removed by the biological treatment, the remained three chlorophenols, biorecalcitrant PCP, and  biodegradation products were completely removed by the subsequent photocatalytic treatment. The combined treatment significantly shortened the degradation time only the biotreatment. High circulative flow rate (600 mL min-1 enabled for TiO2 particles to completely suspend in a tubular photoreactor and resulted in high removals of chlorophenols and TOC. Sunlight irradiation was successfully used and the saving of the electric energy of black light was possible. Since TiO2 particles in the tap water spontaneously sedimented on standing after the photocatalytic treatment, the combined system can be operated by integrating it with the TiO2 separation.   Keywords: photocatalysis, titanium dioxide, biodegradation, pollutant, wastewater

Photocatalytic Activity of Nanostructured Titanium Dioxide Thin Films

Directory of Open Access Journals (Sweden)

Zdenek Michalcik

2012-01-01

Full Text Available The aim of this paper is to investigate the properties and photocatalytic activity of nanostructured TiO2 layers. The glancing angle deposition method with DC sputtering at low temperature was applied for deposition of the layers with various columnar structures. The thin-film structure and surface morphology were analyzed by XRD, SEM, and AFM analyses. The photocatalytic activity of the films was determined by the rate constant of the decomposition of the Acid Orange 7. In dependence on the glancing angle deposition parameters, three types of columnar structures were obtained. The films feature anatase/rutile and/or amorphous structures depending on the film architecture and deposition method. All the films give the evidence of the photocatalytic activity, even those without proved anatase or rutile structure presence. The impact of columnar boundary in perspective of the photocatalytic activity of nanostructured TiO2 layers was discussed as the possible factor supporting the photocatalytic activity.

Photocatalytic hydrogen production on SOLECTRO {sup registered} titanium dioxide layers. Investigation of reaction processes and of the influence of various reaction parameters; Photokatalytische Wasserstoffgewinnung an SOLECTRO {sup registered} -Titandioxidschichten. Untersuchung der ablaufenden Reaktionsprozesse und des Einflusses verschiedener Reaktionsparameter

Energy Technology Data Exchange (ETDEWEB)

Keil, Doreen

2010-04-14

The dissertation investigated the reaction processes of photocatalytic hydrogen production on palladium and copper-doped SOLECTRO {sup registered} titanium dioxide layers. Methanol was used as electron donor. [German] In dieser Doktorarbeit werden die ablaufenden Reaktionsprozesse der photokatalytischen Wasserstoffentwicklung an palladium- und kupferbeladenen SOLECTRO {sup registered} -Titandioxidschichten untersucht. Als Elektronendonator wurde Methanol verwendet.

Preliminary study towards photoactivity enhancement using a biocompatible titanium dioxide/carbon nanotubes composite

Energy Technology Data Exchange (ETDEWEB)

Cendrowski, Krzysztof, E-mail: kcendrowski@zut.edu.pl [West Pomeranian University of Technology Szczecin, Centre of Knowledge Based Nanomaterials and Technologies, Institute of Chemical and Environment Engineering, Pulaskiego 10, Szczecin 70-322 (Poland); Jedrzejczak, Malgorzata [West Pomeranian University of Technology Szczecin, Faculty of Biotechnology and Animal Science, Laboratory of Molecular Cytogenetic, Dr Judyma 10, Szczecin 71-460 (Poland); Peruzynska, Magdalena [Department of Experimental and Clinical Pharmacology, Pomeranian Medical University, al. Powstancow Wielkopolskich 72, Szczecin 70-111 (Poland); Dybus, Andrzej [West Pomeranian University of Technology Szczecin, Faculty of Biotechnology and Animal Science, Laboratory of Molecular Cytogenetic, Dr Judyma 10, Szczecin 71-460 (Poland); Drozdzik, Marek [Department of Experimental and Clinical Pharmacology, Pomeranian Medical University, al. Powstancow Wielkopolskich 72, Szczecin 70-111 (Poland); Mijowska, Ewa [West Pomeranian University of Technology Szczecin, Centre of Knowledge Based Nanomaterials and Technologies, Institute of Chemical and Environment Engineering, Pulaskiego 10, Szczecin 70-322 (Poland)

2014-08-25

Graphical abstract: Scheme demonstrating the experimental steps toward the formation of titania/multiwalled carbon nanotubes (TiO{sub 2}-MWCNTs) from multiwalled carbon nanotubes (MWCNT). - Highlights: • Easy and efficient method of impregnation carbon nanotubes with titania. • High photoactivity. • Correlation between the interaction of carbon nanotubes with titania on the photocatalytic properties. • High biocompatibility of the nanotubes. - Abstract: Recent research is focused on the enhancement in photoactivity of titanium dioxide/carbon nanotubes through formation of novel nanocomposites that exhibit a high specific surface area, remarkable electron transfer and biocompatibility. Here, we explore a new synthesis route in the system composed of nanocrystalline titanium dioxide supported on external walls and inner space of multiwalled carbon nanotubes (MWCNT). The advantages of this method are: its simplicity, direct fusion of titanium dioxide particles on the carbon material, and formation of chemical bond Ti–O–C between TiO{sub 2} and MWCNT. Photocatalytic performance of this system has been compared to a commercial catalyst (Degussa P25) in a model reaction of phenol decomposition in/under UV light. The efficiency of the process increased by the factor of 2.5 when the TiO{sub 2}–MWCNT photocatalyst was utilized. Further, the photoactive nanocomposite was analysed towards its biocompatibility in order to establish a safe dose of the catalyst. Its influence on the cells viability was studied on mouse fibroblasts and human liver tissue cells, in the range from 0 to 100 μg/mL. This has revealed that the composite in concentrations up to 25 μg/mL exerted low toxicity, which allowed for finding a compromise between the highest safe dose and acceptable photoactivity of the catalyst.

Photocatalytic Degradation of Toluene, Butyl Acetate and Limonene under UV and Visible Light with Titanium Dioxide-Graphene Oxide as Photocatalyst

Directory of Open Access Journals (Sweden)

Birte Mull

2017-01-01

Full Text Available Photocatalysis is a promising technique to reduce volatile organic compounds indoors. Titanium dioxide (TiO2 is a frequently-used UV active photocatalyst. Because of the lack of UV light indoors, TiO2 has to be modified to get its working range shifted into the visible light spectrum. In this study, the photocatalytic degradation of toluene, butyl acetate and limonene was investigated under UV LED light and blue LED light in emission test chambers with catalysts either made of pure TiO2 or TiO2 modified with graphene oxide (GO. TiO2 coated with different GO amounts (0.75%–14% were investigated to find an optimum ratio for the photocatalytic degradation of VOC in real indoor air concentrations. Most experiments were performed at a relative humidity of 0% in 20 L emission test chambers. Experiments at 40% relative humidity were done in a 1 m³ emission test chamber to determine potential byproducts. Degradation under UV LED light could be achieved for all three compounds with almost all tested catalyst samples up to more than 95%. Limonene had the highest degradation of the three selected volatile organic compounds under blue LED light with all investigated catalyst samples.

Titanium dioxide thin films by atomic layer deposition: a review

Science.gov (United States)

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.

Role of Platinum Deposited on TiO2 in Photocatalytic Methanol Oxidation and Dehydrogenation Reactions

Directory of Open Access Journals (Sweden)

Luma M. Ahmed

2014-01-01

Full Text Available Titania modified nanoparticles have been prepared by the photodeposition method employing platinum particles on the commercially available titanium dioxide (Hombikat UV 100. The properties of the prepared photocatalysts were investigated by means of the Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, atomic force microscopy (AFM, and UV-visible diffuse spectrophotometry (UV-Vis. XRD was employed to determine the crystallographic phase and particle size of both bare and platinised titanium dioxide. The results indicated that the particle size was decreased with the increasing of platinum loading. AFM analysis showed that one particle consists of about 9 to 11 crystals. UV-vis absorbance analysis showed that the absorption edge shifted to longer wavelength for 0.5% Pt loading compared with bare titanium dioxide. The photocatalytic activity of pure and Pt-loaded TiO2 was investigated employing the photocatalytic oxidation and dehydrogenation of methanol. The results of the photocatalytic activity indicate that the platinized titanium dioxide samples are always more active than the corresponding bare TiO2 for both methanol oxidation and dehydrogenation processes. The loading with various platinum amounts resulted in a significant improvement of the photocatalytic activity of TiO2. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole charge carriers.

Exfoliated graphite/titanium dioxide nanocomposites for photodegradation of eosin yellow

International Nuclear Information System (INIS)

Ndlovu, Thabile; Kuvarega, Alex T.; Arotiba, Omotayo A.; Sampath, Srinivasan; Krause, Rui W.; Mamba, Bhekie B.

2014-01-01

Graphical abstract: - Highlights: • Preparation of exfoliated graphite (EG) from natural graphite. • Sol–gel anchoring of TiO 2 on exfoliated graphite. • High adsorption and photoactivity was observed for the EG-TiO 2 nanocomposite. • Mechanism of enhancement was proposed. - Abstract: An improved photocatalyst consisting of a nanocomposite of exfoliated graphite and titanium dioxide (EG-TiO 2 ) was prepared. SEM and TEM micrographs showed that the spherical TiO 2 nanoparticles were evenly distributed on the surface of the EG sheets. A four times photocatalytic enhancement was observed for this floating nanocomposite compared to TiO 2 and EG alone for the degradation of eosin yellow. For all the materials, the reactions followed first order kinetics where for EG-TiO 2 , the rate constant was much higher than for EG and TiO 2 under visible light irradiation. The enhanced photocatalytic activity of EG-TiO 2 was ascribed to the capability of graphitic layers to accept and transport electrons from the excited TiO 2 , promoting charge separation. This indicates that carbon, a cheap and abundant material, can be a good candidate as an electron attracting reservoir for photocatalytic organic pollutant degradation

Increasing Solar Absorption for Photocatalysis with Black Hydrogenated Titanium Dioxide Nanocrystals

KAUST Repository

Chen, X.

2011-01-20

When used as a photocatalyst, titanium dioxide (TiO 2) absorbs only ultraviolet light, and several approaches, including the use of dopants such as nitrogen, have been taken to narrow the band gap of TiO 2. We demonstrated a conceptually different approach to enhancing solar absorption by introducing disorder in the surface layers of nanophase TiO 2 through hydrogenation. We showed that disorder-engineered TiO 2 nanocrystals exhibit substantial solar-driven photocatalytic activities, including the photo-oxidation of organic molecules in water and the production of hydrogen with the use of a sacrificial reagent.

Increasing Solar Absorption for Photocatalysis with Black Hydrogenated Titanium Dioxide Nanocrystals

KAUST Repository

Chen, X.; Liu, L.; Yu, P. Y.; Mao, S. S.

2011-01-01

When used as a photocatalyst, titanium dioxide (TiO 2) absorbs only ultraviolet light, and several approaches, including the use of dopants such as nitrogen, have been taken to narrow the band gap of TiO 2. We demonstrated a conceptually different approach to enhancing solar absorption by introducing disorder in the surface layers of nanophase TiO 2 through hydrogenation. We showed that disorder-engineered TiO 2 nanocrystals exhibit substantial solar-driven photocatalytic activities, including the photo-oxidation of organic molecules in water and the production of hydrogen with the use of a sacrificial reagent.

Investigation of titanium dioxide/ tungstic acid -based photocatalyst for human excrement wastewater treatment

Science.gov (United States)

Xu, Fei; Wang, Can; Xiao, Kemeng; Gao, Yufeng; Zhou, Tong; Xu, Heng

2018-05-01

An activated carbon (AC) coated with tungstic acid (WO3)/titanium dioxide (TiO2) nanocomposites photocatalytic material (ACWT) combined with Three-phase Fluidized Bed (TFB) was investigated for human excrement wastewater treatment. Under the ultraviolet (UV) and fluorescent lamp illumination, the ACWT had shown a good performance on chemical oxygen demand (COD) and total nitrogen (TN) removal but inefficient on ammonia nitrogen (NH3-N) removal. Optimized by Taguchi method, COD and TN removal efficiency was up to 88.39% and 55.07%, respectively. Among all the parameters, the dosage of ACWT had the largest contribution on the process. Bacterial community changes after treatment demonstrated that this photocatalytic system had a great sterilization effect on wastewater. These results confirmed that ACWT could be applied for the human excrement wastewater treatment.

Thermoexpanded graphite modification by titanium dioxide

International Nuclear Information System (INIS)

Semko, L.S.; Gorbik, P.P.; Chujko, O.O.; Kruchek, Ya.Yi.; Dzyubenko, L.S.; Orans'ka, O.Yi.

2006-01-01

A method of the synthesis of thermoexpanded graphite (TEG) powders coated by titanium dioxide is developed. The conversion of n-buthylorthotitanate into TiO 2 on the TEG surface is investigated. The optimal parameters of the synthesis and the structure of titanium dioxide clusters on the TEG surface are determined

Classification of titanium dioxide; Clasificacion del dioxido de titanio

Energy Technology Data Exchange (ETDEWEB)

Macias B, L.R. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Garcia C, R.M.; Maya M, M.E. [Secretaria de Hacienda y Credito Publico de Mexico, Mexico (Mexico); Ita T, A. De [Universidad Autonoma Metropolitana Azcapotzalco, Mexico (Mexico); Palacios G, J. [Instituto Politecnico Nacional (Mexico)

2002-07-01

In this work the X-ray diffraction (XRD), Scanning Electron Microscopy (Sem) and the X-ray Dispersive Energy Spectroscopy techniques are used with the purpose to achieve a complete identification of phases and mixture of phases of a crystalline material as titanium dioxide. The problem for solving consists of being able to distinguish a sample of titanium dioxide being different than a titanium dioxide pigment. A standard sample of titanium dioxide with NIST certificate is used, which indicates a purity of 99.74% for the TiO{sub 2}. The following way is recommended to proceed: a)To make an analysis by means of X-ray diffraction technique to the sample of titanium dioxide pigment and on the standard of titanium dioxide waiting not find differences. b) To make a chemical analysis by the X-ray Dispersive Energy Spectroscopy via in a microscope, taking advantage of the high vacuum since it is oxygen which is analysed and if it is concluded that the aluminium oxide appears in a greater proportion to 1% it is established that is a titanium dioxide pigment, but if it is lesser then it will be only titanium dioxide. This type of analysis is an application of the nuclear techniques useful for the tariff classification of merchandise which is considered as of difficult recognition. (Author)

Effect of amorphous fluorinated coatings on photocatalytic properties of anodized titanium surfaces

Energy Technology Data Exchange (ETDEWEB)

Persico, Federico [Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, via Mancinelli 7, 20131, Milano (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze (Italy); Sansotera, Maurizio, E-mail: maurizio.sansotera@polimi.it [Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, via Mancinelli 7, 20131, Milano (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze (Italy); Diamanti, Maria Vittoria [Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, via Mancinelli 7, 20131, Milano (Italy); Magagnin, Luca; Venturini, Francesco; Navarrini, Walter [Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, via Mancinelli 7, 20131, Milano (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze (Italy)

2013-10-31

The photocatalytic activity promoted by anodized titanium surfaces coated with different amorphous perfluoropolymers was evaluated. A copolymer between tetrafluoroethylene and perfluoro-4-trifluoromethoxy-1,3-dioxole and two perfluoropolyethers containing ammonium phosphate and triethoxysilane functionalities, respectively, were tested as coating materials. These coatings revealed good adhesion to the anodized titanium substrate and conferred to it both hydrophobicity and oleophobicity. The photocatalytic activity of the coating on anodized titanium was evaluated by monitoring the degradation of stearic acid via Infrared spectroscopy. The degradation rate of stearic acid was reduced but not set to zero by the presence of the fluorinated coatings, leading to the development of advanced functional coatings. The morphological variations of the coatings as a result of photocatalysis were also determined by atomic force microscopy. - Highlights: • Coated anodized titanium surfaces show a decreased wettability. • Evaluation of the stability of perfluorinated coatings towards photocatalysis. • Amorphous perfluorinated coatings do not hinder photocatalytic activity.

Biophotofuel cell anode containing self-organized titanium dioxide nanotube array

Energy Technology Data Exchange (ETDEWEB)

Gan, Yong X., E-mail: yong.gan@utoledo.edu [Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, 2801 W Bancroft Street, Toledo, OH 43606 (United States); Gan, Bo J. [Ottawa Hills High School, 2532 Evergreen Road, Toledo, OH 43606 (United States); Su Lusheng [Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, 2801 W Bancroft Street, Toledo, OH 43606 (United States)

2011-09-15

Graphical abstract: Highlights: {center_dot} A photoactive anode containing highly ordered TiO{sub 2} nanotube array was made and the formation mechanism of self-organized TiO{sub 2} nanotube array on Ti was revealed. {center_dot} Effect of electrolyte concentration and voltage on the size distribution of the nanotubes was investigated. {center_dot} Self-organized TiO{sub 2} nanotube array anode possesses good photo-catalytic behavior of biomass decomposition under ultraviolet (UV) radiation. {center_dot} The fuel cell generates electricity and hydrogen via photoelectrochemical decomposition of ethanol, apple vinegar, sugar and tissue paper. - Abstract: We made a biophotofuel cell consisting of a titanium dioxide nanotube array photosensitive anode for biomass decomposition, and a low-hydrogen overpotential metal, Pt, as the cathode for hydrogen production. The titanium dioxide nanotubes (TiO{sub 2} NTs) were prepared via electrochemical oxidation of pure Ti in NaF solutions. Scanning electron microscopy was used to analyze the morphology of the nanotubes. The average diameter, wall thickness and length of the as-prepared TiO{sub 2} NTs were 88 {+-} 16 nm, 10 {+-} 2 nm and 491 {+-} 56 nm, respectively. Such dimensions are affected by the NaF concentration and the applied voltage during processing. Higher NaF concentrations result in the formation of longer and thicker nanotubes. The higher the voltage is, the thicker the nanotubes. The photosensitive anode made from the highly ordered TiO{sub 2} NTs has good photo-catalytic property, as can be seen from the test results of ethanol, apple vinegar, sugar and tissue paper decomposition under ultraviolet (UV) radiation. It is concluded that the biophotofuel cell with the TiO{sub 2} nanotube photoanode and a Pt cathode can generate electricity, hydrogen and clean water depending on the pH value and the oxygen presence in the solutions.

Comparative photocatalytic study of two selected pesticide derivatives, indole-3-acetic acid and indole-3-butyric acid in aqueous suspensions of titanium dioxide

Energy Technology Data Exchange (ETDEWEB)

Qamar, M. [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Muneer, M. [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India)]. E-mail: cht12mm@amu.ac.in

2005-04-11

Heterogeneous photocatalysed degradation of two selected pesticide derivatives such as indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) has been investigated in aqueous suspensions of titanium dioxide by monitoring the change in substrate concentration employing UV spectroscopic analysis technique and depletion in total organic carbon (TOC) content as a function of irradiation time. The degradation kinetics was studied under different conditions such as pH, types of TiO{sub 2,} substrate and catalyst concentration, and in the presence of electron acceptor such as hydrogen peroxide (H{sub 2}O{sub 2}) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 showed comparatively highest photocatalytics. The pesticide derivative, indole-3-acetic acid was found to degrade slightly faster than indole-3-butyric acid.

Potential for photocatalytic degradation of the potassic diclofenac using scandium and silver modified titanium dioxide thin films; Potencial de degradacao fotocatalitica do diclofenaco potassico utilizando filmes finos de dioxido de titanio modificado com escandio e prata

Energy Technology Data Exchange (ETDEWEB)

Ciola, R.A.; Oliveira, C.T.; Lopes, S.A.; Cavalheiro, A.A., E-mail: rafaelciola@hotmail.com [Universidade Estadual de Mato Grosso do Sul (UFMS), Navirai, MS (Brazil). Centro de Pesquisas Tecnologicas em Recursos Naturais

2011-07-01

The potential for photocatalytic degradation of the potassic diclofenac drug was investigated using titanium dioxide thin films modified with two modifier types, scandium and silver, both prepared by Sol-Gel method. It was demonstrated by UVVis spectroscopy analysis of the solutions containing the drug, under UV-A light irradiation that the degradation efficiency of the titanium dioxide photocatalyst is dependent of the semiconductor nature and that the scandium accelerates the first step of the degradation when compared to the silver. This result seems to be related to the redox potential of the electron-hole pair, once the scandium modifying sample generates a p type semiconductor that reduces the band gap. The extra holes attract more strongly the chorine ion present in diclofenac and leading to the releasing more easily. However, after the first byproducts degradation the following steps are not facilitated, making the silver modifying more advantageous. (author)

Exfoliated graphite/titanium dioxide nanocomposites for photodegradation of eosin yellow

Energy Technology Data Exchange (ETDEWEB)

Ndlovu, Thabile, E-mail: atkuvarega@gmail.com [University of Swaziland, Department of Chemistry, Private Bag 4, Kwaluseni (Swaziland); Kuvarega, Alex T.; Arotiba, Omotayo A. [University of Johannesburg, Department of Applied Chemistry, P.O. Box 17011, Doornfontein 2028, Johannesburg (South Africa); Sampath, Srinivasan [Indian Institute of Science, Department of Inorganic and Physical Chemistry, Bangalore 560012 (India); Krause, Rui W. [Rhodes University, Department of Chemistry, P.O. Box 94, Grahamstown 6140 South Africa (South Africa); Mamba, Bhekie B., E-mail: bmamba@uj.ac.za [University of Johannesburg, Department of Applied Chemistry, P.O. Box 17011, Doornfontein 2028, Johannesburg (South Africa)

2014-05-01

Graphical abstract: - Highlights: • Preparation of exfoliated graphite (EG) from natural graphite. • Sol–gel anchoring of TiO{sub 2} on exfoliated graphite. • High adsorption and photoactivity was observed for the EG-TiO{sub 2} nanocomposite. • Mechanism of enhancement was proposed. - Abstract: An improved photocatalyst consisting of a nanocomposite of exfoliated graphite and titanium dioxide (EG-TiO{sub 2}) was prepared. SEM and TEM micrographs showed that the spherical TiO{sub 2} nanoparticles were evenly distributed on the surface of the EG sheets. A four times photocatalytic enhancement was observed for this floating nanocomposite compared to TiO{sub 2} and EG alone for the degradation of eosin yellow. For all the materials, the reactions followed first order kinetics where for EG-TiO{sub 2}, the rate constant was much higher than for EG and TiO{sub 2} under visible light irradiation. The enhanced photocatalytic activity of EG-TiO{sub 2} was ascribed to the capability of graphitic layers to accept and transport electrons from the excited TiO{sub 2}, promoting charge separation. This indicates that carbon, a cheap and abundant material, can be a good candidate as an electron attracting reservoir for photocatalytic organic pollutant degradation.

Photocatalytic selective oxidation of phenol in suspensions of titanium dioxide with exposed {0 0 1} facets

International Nuclear Information System (INIS)

Ye, Hengpeng; Lu, Shaoming

2013-01-01

Anatase TiO 2 nanocrystals with exposed {0 0 1} facets were tailored by hydrothermal treatment of Ti(OC 4 H 9 ) 4 –HF–H 2 O mixed solution. The photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption isotherms and X-ray photoelectron spectroscopy (XPS). The effect of structure of the photocatalyst on the photocatalytic selective oxidation of phenol under UV irradiation was studied. The experiment results showed that (1) the percentage of the exposed {0 0 1} facets of the nanocrystal increases with increasing the nominal atomic ratio of fluorine to titanium (R F ), (2) catechol and hydroquinone are main intermediates detected during photocatalytic oxidation of phenol, and (3) both photocatalytic oxidation of phenol and selectivity (yield) of catechol are positively correlated with the percentage of exposed {0 0 1} facets of the high-energy TiO 2 nanocrystals. The enhanced conversion of phenol and selectivity (yield) of catechol were ascribed to the synergistic effects of the exposed high-energy {0 0 1} facets and surface fluorination. This study may provide new insight into the selective oxidation of organics.

Array of titanium dioxide nanostructures for solar energy utilization

Science.gov (United States)

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.

On reaction of titanium polonides with carbon dioxide

International Nuclear Information System (INIS)

Abakumov, A.S.; Malyshev, M.L.; Reznikova, N.F.

1986-01-01

The reaction between titanium polonides and carbon dioxide has been studied by comparing titanium polonide thermal resistance in vacuum and in carbon dioxide. The investigation has shown that titanium mono- and semipolonides fail at temperatures below 350 deg C. Temperature dependence of polonium vapor pressure prepared at failure of the given polonides is determined by the radiotensiometry in carbon dioxide. Enthalpy calculated for this dependence is close to the enthalpy of elementary polonium evaporation in vacuum

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

Science.gov (United States)

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 ...

Photocatalytic reduction of nitrate using titanium dioxide for regeneration of ion exchange brine.

Science.gov (United States)

Yang, Ting; Doudrick, Kyle; Westerhoff, Paul

2013-03-01

Nitrate is often removed from groundwater by ion exchange (IX) before its use as drinking water. Accumulation of nitrate in IX brine reduces the efficiency of IX regeneration and the useful life of the regeneration brine. For the first time, we present a strategy to photocatalytically reduce nitrate in IX brine, thereby extending the use of the brine. Titanium dioxide (Evonik P90), acting as photocatalyst, reduced nitrate effectively in both synthetic brines and sulfate-removed IX brine when formic acid (FA) was used as the hole scavenger (i.e., electron donor) and the initial FA to nitrate molar ratio (IFNR) was 5.6. Increasing the NaCl level in the synthetic brine slowed the nitrate reduction rate without affecting by-product selectivity of ammonium and gaseous N species (e.g., N(2), N(2)O). In a non-modified IX brine, nitrate removal was greatly inhibited owing to the presence of sulfate, which competed with nitrate for active surface sites on P90 and induced aggregation of P90 nanoparticles. After removing sulfate through barium sulfate precipitation, nitrate was effectively reduced; approximately 3.6 × 10(24) photons were required to reduce each mole of nitrate to 83% N Gases and 17% NH(4)(+). To make optimum use of FA and control the residual FA level in treated brine, the IFNR was varied. High IFNRs (e.g., 4, 5.6) were found to be more efficient for nitrate reduction but left higher residual FA in brine. IX column tests were performed to investigate the impact of residual FA for brine reuse. The residual FA in the brine did not significantly affect the nitrate removal capacity of IX resins, and formate contamination of treated water could be eliminated by rinsing with one bed volume of fresh brine. Copyright © 2012 Elsevier Ltd. All rights reserved.

Sorption kinetics of cesium on hydrous titanium dioxide

International Nuclear Information System (INIS)

Altas, Y.; Tel, H.; Yaprak, G.

2003-01-01

Two types of hydrous titanium dioxide possessing different surface properties were prepared and characterized to study the sorption kinetics of cesium. The effect of pH on the adsorption capacity were determined in both type sorbents and the maximum adsorption percentage of cesium were observed at pH 12. To elucidate the kinetics of ion-exchange reaction on hydrous titanium dioxide, the isotopic exchange rates of cesium ions between hydrous titanium dioxides and aqueous solutions were measured radiochemically and compared with each other. The diffusion coefficients of Cs + ion for Type1 and Type2 titanium dioxides at pH 12 were calculated as 2.79 x 10 -11 m 2 s -1 and 1.52 x 10 -11 m 2 s -1 , respectively, under particle diffusion controlled conditions. (orig.)

Physical and rheological properties of Titanium Dioxide modified asphalt

Science.gov (United States)

Buhari, Rosnawati; Ezree Abdullah, Mohd; Khairul Ahmad, Mohd; Chong, Ai Ling; Haini, Rosli; Khatijah Abu Bakar, Siti

2018-03-01

Titanium Dioxide (TiO2) has been known as a useful photocatalytic material that is attributed to the several characteristics includes high photocatalytic activity compared with other metal oxide photocatalysts, compatible with traditional construction materials without changing any original performance. This study investigates the physical and rheological properties of modified asphalt with TiO2. Five samples of asphalt with different concentration of TiO2 were studied, namely asphalt 2%, 4%, 6% 8% and 10% TiO2. The tests includes are penetration, softening point, ductility, rotational viscosity and dynamic shear rheometer (DSR) test. From the results of this study, it is noted that addition of TiO2 has significant effect on the physical properties of asphalt. The viscosity tests revealed that asphalt 10% TiO2 has good workability among with reducing approximately 15°C compared to base asphalt. Based on the results from DSR measurements, asphalt 10% TiO2 has reduced temperature susceptibility and increase stiffness and elastic behaviour in comparison to base asphalt. As a result, TiO2 can be considered to be an additive to modify the properties of asphalt.

The immunomodulatory effects of titanium dioxide and silver nanoparticles.

Science.gov (United States)

Lappas, Courtney M

2015-11-01

Due to their characteristic physical, chemical and optical properties, titanium dioxide and silver nanoparticles are attractive tools for use in a wide range of applications. The use of nanoparticles for biological applications is, however, dependent upon their biocompatibility with living cells. Because of the importance of inflammation as a modulator of human health, the safe and efficacious in vivo use of titanium dioxide and silver nanoparticles is inherently linked to a favorable interaction with immune system cells. However, both titanium dioxide and silver nanoparticles have demonstrated potential to exert immunomodulatory and immunotoxic effects. Titanium dioxide and silver nanoparticles are readily internalized by immune system cells, may accumulate in peripheral lymphoid organs, and can influence multiple manifestations of immune cell activity. Although the factors influencing the biocompatibility of titanium dioxide and silver nanoparticles with immune system cells have not been fully elucidated, nanoparticle core composition, size, concentration and the duration of cell exposure seem to be important. Because titanium dioxide and silver nanoparticles are widely utilized in pharmaceutical, commercial and industrial products, it is vital that their effects on human health and immune system function be more thoroughly evaluated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of food processing organic matter on photocatalytic bactericidal activity of titanium dioxide (TiO2).

Science.gov (United States)

Yemmireddy, Veerachandra K; Hung, Yen-Con

2015-07-02

The purpose of this study was to determine the effect of food processing organic matter on photocatalytic bactericidal activity of titanium dioxide (TiO2) nanoparticles (NPs). Produce and meat processing wash solutions were prepared using romaine lettuce and ground beef samples. Physico-chemical properties such as pH, turbidity, chemical oxygen demand (COD), total phenolics (for produce) and protein (for meat) content of the extracts were determined using standard procedures. The photocatalytic bactericidal activity of TiO2 (1 mg/mL) in suspension with or without organic matter against Escherichia coli O157:H7 (5-strain) was determined over a period of 3h. Increasing the concentration of organic matter (either produce or meat) from 0% to 100% resulted in 85% decrease in TiO2 microbicidal efficacy. 'Turbidity, total phenolics, and protein contents in wash solutions had significant effect on the log reduction. Increasing the total phenolics content in produce washes from 20 to 114 mg/L decreased the log reduction from 2.7 to 0.38 CFU/mL, whereas increasing the protein content in meat washes from 0.12 to 1.61 mg/L decreased the log reduction from and 5.74 to 0.87 CFU/mL. Also, a linear correlation was observed between COD and total phenolics as well as COD and protein contents. While classical disinfection kinetic models failed to predict, an empirical equation in the form of "Y=me(nX)" (where Y is log reduction, X is COD, and m and n are reaction rate constants) predicted the disinfection kinetics of TiO2 in the presence of organic matter (R(2)=94.4). This study successfully identified an empirical model with COD as a predictor variable to predict the bactericidal efficacy of TiO2 when used in food processing environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Titanium-dioxide nanotube p-n homojunction diode

Science.gov (United States)

Alivov, Yahya; Ding, Yuchen; Singh, Vivek; Nagpal, Prashant

2014-12-01

Application of semiconductors in functional optoelectronic devices requires precise control over their doping and formation of junction between p- and n-doped semiconductors. While doped thin films have led to several semiconductor devices, need for high-surface area nanostructured devices for photovoltaic, photoelectrochemical, and photocatalytic applications has been hindered by lack of desired doping in nanostructures. Here, we show titanium-dioxide (TiO2) nanotubes doped with nitrogen (N) and niobium (Nb) as acceptors and donors, respectively, and formation of TiO2 nanotubes p-n homojunction. This TiO2:N/TiO2:Nb homojunction showed distinct diode-like behaviour with rectification ratio of 1115 at ±5 V and exhibited good photoresponse for ultraviolet light (λ = 365 nm) with sensitivity of 0.19 A/W at reverse bias of -5 V. These results can have important implications for development of nanostructured metal-oxide solar-cells, photodiodes, LED's, photocatalysts, and photoelectrochemical devices.

Titanium-dioxide nanotube p-n homojunction diode

Energy Technology Data Exchange (ETDEWEB)

Alivov, Yahya, E-mail: y.alivov@colorado.edu, E-mail: pnagpal@colorado.edu; Ding, Yuchen; Singh, Vivek [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Nagpal, Prashant, E-mail: y.alivov@colorado.edu, E-mail: pnagpal@colorado.edu [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Materials Science and Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Renewable and Sustainable Energy Institute, University of Colorado Boulder, 2445 Kittredge Loop, Boulder, Colorado 80309 (United States)

2014-12-29

Application of semiconductors in functional optoelectronic devices requires precise control over their doping and formation of junction between p- and n-doped semiconductors. While doped thin films have led to several semiconductor devices, need for high-surface area nanostructured devices for photovoltaic, photoelectrochemical, and photocatalytic applications has been hindered by lack of desired doping in nanostructures. Here, we show titanium-dioxide (TiO{sub 2}) nanotubes doped with nitrogen (N) and niobium (Nb) as acceptors and donors, respectively, and formation of TiO{sub 2} nanotubes p-n homojunction. This TiO{sub 2}:N/TiO{sub 2}:Nb homojunction showed distinct diode-like behaviour with rectification ratio of 1115 at ±5 V and exhibited good photoresponse for ultraviolet light (λ = 365 nm) with sensitivity of 0.19 A/W at reverse bias of −5 V. These results can have important implications for development of nanostructured metal-oxide solar-cells, photodiodes, LED's, photocatalysts, and photoelectrochemical devices.

Preparation of silica doped titania nanoparticles with thermal stability and photocatalytic properties and their application for leather surface functionalization

Directory of Open Access Journals (Sweden)

Carmen Gaidau

2017-11-01

Full Text Available Doped nanoparticles based on titanium dioxide are of interest for their multifunctional properties and enlarged photocatalytic activity in visible domain. Silica doped titanium dioxide nanoparticles were prepared by hydrothermal method and their structural characteristics and photocatalytic activity were determined, in order to be used for leather coating as alternative to halogen based flame retardants and dry cleaning solvents. A range of concentrations from 2% to 20% silica doped titanium dioxide nanoparticles (% denotes the theoretical weight percent of Si was synthesized and characterized by ICP-OES, FT-IR, UV-vis spectroscopy, XRD, HRTEM and DLS. Titanium dioxide network penetration was supported by Si-O-Ti and OH identification in FT-IR spectra mainly on surface of 10% and 20% silica doped titanium dioxide nanoparticles. The increase of Si-O-Ti bonds with Si dopant concentration acts as efficient barriers against sinterization and growth of TiO2 particles and explains the low particle size identified in HRTEM analyses as compared to undoped TiO2NPs. UV-vis diffuse reflectance spectra of doped titanium dioxide nanoparticles showed the shifting of absorption band to visible domain for 10% silica doped titanium dioxide nanoparticles. The crystallite sizes were calculated from XRD spectra, ranging between 16.2 and 18.1 nm. HRTEM measurement of hydrothermally synthesized titanium dioxide nanoparticles showed anatase crystallites in the range of 8.8–27 nm, while in the 20% silica doped titanium dioxide nanoparticle sample smaller crystallite with sizes between 2.7 nm and 3.5 nm was identified due to the constraints of the SiO2-based amorphous matrix. Nano sizes of 64 nm and 72 nm were found in water dispersions of 10% and 20% silica doped titanium dioxide nanoparticles and the Zeta potentials were of −53.6 mV and −52.9 mV, which indicate very good stabilities. The leather surface treated with composites of film forming polymers

Reaction of titanium polonides with carbon dioxide

International Nuclear Information System (INIS)

Abakumov, A.S.; Malyshev, M.L.; Reznikova, N.F.

1987-01-01

It has been ascertained that heating titanium and tantalum in carbon dioxide to temperatures of 500 or 800 0 C alters the composition of the gas phase, causing the advent of carbon monoxide and lowering the oxygen content. Investigation of the thermal stability of titanium polonides in a carbon dioxide medium has shown that titanium mono- and hemipolonides are decomposed at temperatures below 350 0 C. The temperature dependence of the vapor pressure of polonium produced in the decomposition of these polonides in a carbon dioxide medium have been determined by a radiotensimetric method. The enthalpy of the process, calculated from this relationship, is close to the enthalpy of vaporization of elementary polonium in vacuo

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

Science.gov (United States)

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...

Anodic growth of titanium dioxide nanostructures

DEFF Research Database (Denmark)

2010-01-01

Disclosed is a method of producing nanostructures of titanium dioxide (TiO 2 ) by anodisation of titanium (Ti) in an electrochemical cell, comprising the steps of: immersing a non-conducting substrate coated with a layer of titanium, defined as the anode, in an electrolyte solution...... an electrical contact to the layer of titanium on the anode, where the electrical contact is made in the electrolyte solution...

Plasmonic Titanium Nitride Nanostructures via Nitridation of Nanopatterned Titanium Dioxide

DEFF Research Database (Denmark)

Guler, Urcan; Zemlyanov, Dmitry; Kim, Jongbum

2017-01-01

Plasmonic titanium nitride nanostructures are obtained via nitridation of titanium dioxide. Nanoparticles acquired a cubic shape with sharper edges following the rock-salt crystalline structure of TiN. Lattice constant of the resulting TiN nanoparticles matched well with the tabulated data. Energy...

Titanium dioxide modified with various amines used as sorbents of carbon dioxide

International Nuclear Information System (INIS)

Kapica-Kozar, Joanna; Pirog, Ewa; Kusiak-Nejman, Ewelina; Wrobel, Rafal J.; Gesikiewicz-Puchalska, Andzelika; Morawski, Antoni W.; Narkiewicz, Urszula; Michalkiewicz, Beata

2017-01-01

In this study, titanium dioxide was modified with various amines through hydrothermal treatment for adsorption of CO_2. The carbon dioxide adsorption performance of the prepared samples was measured using an STA 449 C thermo-balance (Netzsch Company, Germany). The morphological structures, functional groups and elemental compositions of the unmodified and amine-modified titanium dioxide sorbents were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR/DR) and scanning electron microscopy (SEM), respectively. The results showed that modification of TiO_2 with amines through hydrothermal treatment is a simple method to prepare CO_2 sorbents with high adsorption capacities. Moreover, the results revealed that TEPA-modified titanium dioxide shoved the highest adsorption capacity, enabling an increase in CO_2 uptake from 0.45 mmol CO_2 g"-"1 in the case of raw TiO_2 to 1.63 mmol CO_2 g"-"1. This result could be indirectly related to the fact that TEPA has the highest amino group content among the three amines used in our research. Additionally, durability tests performed by cyclic adsorption-desorption revealed that TEPA modified titanium dioxide also possesses excellent stability, despite a slight decrease in adsorption capacity over time. (authors)

Titanium dioxide nanotube membranes for solar energy conversion: effect of deep and shallow dopants.

Science.gov (United States)

Ding, Yuchen; Nagpal, Prashant

2017-04-12

Nanostructured titanium dioxide (TiO 2 ) has been intensively investigated as a material of choice for solar energy conversion in photocatalytic, photoelectrochemical, photovoltaic, and other photosensitized devices for converting light into chemical feedstocks or electricity. Towards management of light absorption in TiO 2 , while the nanotubular structure improves light absorption and simultaneous charge transfer to mitigate problems due to the indirect bandgap of the semiconductor, typically dopants are used to improve light absorption of incident solar irradiation in the wide bandgap of TiO 2 . While these dopants can be critical to the success of these solar energy conversion devices, their effect on photophysical and photoelectrochemical properties and detailed photokinetics are relatively under-studied. Here, we show the effect of deep and shallow metal dopants on the kinetics of photogenerated charged carriers in TiO 2 and the resulting effect on photocatalytic and photoelectrochemical processes using these nanotube membranes. We performed a detailed optical, electronic, voltammetry and electrochemical impedance study to understand the effect of shallow and deep metal dopants (using undoped and niobium- and copper-doped TiO 2 nanotubes) on light absorption, charge transport and charge transfer processes. Using wireless photocatalytic methylene blue degradation and carbon dioxide reduction, and wired photoelectrochemical device measurements, we elucidate the effect of different dopants on solar-to-fuel conversion efficiency and simultaneously describe the photokinetics using a model, to help design better energy conversion devices.

Photocatalytic Degradation of Oil using Polyvinylidene Fluoride/Titanium Dioxide Composite Membrane for Oily Wastewater Treatment

Directory of Open Access Journals (Sweden)

Rusli Ummi Nadiah

2016-01-01

Full Text Available Production of industrial wastewater is increasing as the oil and gas industry grows rapidly over the years. The constituents in the industrial wastewater such as organic and inorganic matters, dispersed and lubricant oil and metals which have high toxicity become the major concern to the environment and ecosystem. There are many technologies are being used for oil removal from industrial wastewater. However, there are still needs to find an effective technology to treat oily wastewater before in can be discharge safely to the environment. Membrane technology is an attractive separation technology to treat oily wastewater. The aim of this study is to fabricate polyvinylidene/titanium dioxide (PVDF/TiO2 composite membrane with further treatment using hot pressed method to enhance the adhesion between TiO2 with the membrane surfaces. In this study the structural and physical properties of fabricated membrane were conducted using X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FTIR respectively. The photocatalytic degradation of oil was measured using UV-Vis Spectroscopy. The FTIR results confirmed that, hot pressed PVDF/TiO2 membrane TiO2 was successfully deposited onto PVDF membranes surface and XRD results shows that the XRD pattern of PVDF//TiO2 found that the crystalline structure was remained unchanged after hot pressed. Clear water was obtained after synthetic oily wastewater was exposed to visible light for at least 6 hours. In conclusion, PVDF/TiO2 composite membrane can be a potential candidate to degrade oil in oily wastewater and suggested to possess an excellent performance if perform simultaneously with membrane separation process.

Development of bifunctional microencapsulated phase change materials with crystalline titanium dioxide shell for latent-heat storage and photocatalytic effectiveness

International Nuclear Information System (INIS)

Chai, Luxiao; Wang, Xiaodong; Wu, Dezhen

2015-01-01

Highlights: • We designed and synthesized a sort of bifunctional PCMs-based microcapsules. • These microcapsules have an n-eicosane core and a crystalline TiO 2 shell. • Such a crystalline TiO 2 shell exhibited a good photocatalytic activity. • The microcapsules showed good performance in energy storage and sterilization. - Abstract: A sort of novel bifunctional microencapsulated phase change material (PCM) was designed by encapsulating n-eicosane into a crystalline titanium dioxide (TiO 2 ) shell and, then, was successfully synthesized through in-situ polycondensation in the sol–gel process using tetrabutyl titanate as a titania precursor. The resultant microcapsule samples were characterized by Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to determine their chemical compositions and structures. Furthermore, the crystallinity of the TiO 2 shell was verified by powder X-ray diffraction patterns. It was confirmed that the fluorinions could induce the phase transition from the amorphous TiO 2 to the brookite-form crystals during the sol–gel process, thus resulting in a crystalline TiO 2 shell for the microencapsulated n-eicosane. The scanning and transmission electron microscopy investigations indicated that all of the resultant microcapsules presented a perfect spherical shape with a uniform particle size of 1.5–2 μm, and they also exhibited a well-defined core–shell structure as well as a smooth and compact shell. The crystalline TiO 2 shell made the resultant microcapsules a photocatalytic activity, and therefore, these microcapsules demonstrated a good photocatalytic effect for the chemical degradation and an antimicrobial function for some of the Gram-negative bacteria. Most of all, all of the microencapsulated n-eicosane samples indicated good phase-change performance and high thermal reliability for latent-heat storage and release, and moreover, they achieved a high

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

Science.gov (United States)

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...

Nanostructured titanium dioxide: a control of crystallite size and content of polymorphic phases

International Nuclear Information System (INIS)

Boery, Mirella N. de O.; Ono, Eduardo; Manfrim, Tarcio P.; Santos, Juliana S.; Suzuki, Carlos K.

2010-01-01

TiO 2 (titanium dioxide) powders and nanoparticles have been largely used in toners and cosmetics. Nowadays, they are mainly focused in photocatalysis, antibacterial coatings, dye-sensitized solar cells, etc. The efficiency is related to photocatalytic properties of TiO 2 nanoparticles, such as crystallite size and phase (anatasio/rutile). In this research, flame aerosol method was used to synthesize TiO 2 nanoparticles by hydrolysis and oxidation of TiCl 4 (titanium tetrachloride). The oxy-hydrogen flame was provided by a five concentric nozzle silica burner. X-ray diffraction was used to identify each TiO 2 nanoparticles phase and scanning electron microscopy was used to observe the size and morphology of nanoparticles. Pure anatase was obtained with H 2 /O 2 ratio ≤ 1.0, and up to 52 wt% of rutile was obtained with H 2 /O 2 ratio > 2.0. Anatase crystal grain size varied from 25 to 38 nm, estimated by Scherrer formula.(author)

Titanium-Phosphonate-Based Metal-Organic Frameworks with Hierarchical Porosity for Enhanced Photocatalytic Hydrogen Evolution

KAUST Repository

Li, Hui

2018-02-01

Photocatalytic hydrogen production is crucial for solar-to-chemical conversion process, wherein high-efficiency photocatalysts lie in the heart of this area. Herein a new photocatalyst of hierarchically mesoporous titanium-phosphonate-based metal-organic frameworks, featuring well-structured spheres, periodic mesostructure and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well-structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemical field.

Titanium-Phosphonate-Based Metal-Organic Frameworks with Hierarchical Porosity for Enhanced Photocatalytic Hydrogen Evolution

KAUST Repository

Li, Hui; Sun, Ying; Yuan, Zhong-Yong; Zhu, Yun-Pei; Ma, Tianyi

2018-01-01

Photocatalytic hydrogen production is crucial for solar-to-chemical conversion process, wherein high-efficiency photocatalysts lie in the heart of this area. Herein a new photocatalyst of hierarchically mesoporous titanium-phosphonate-based metal-organic frameworks, featuring well-structured spheres, periodic mesostructure and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well-structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemical field.

Kinetic study of synthesis of Titanium carbide by methano thermal reduction of Titanium dioxide

International Nuclear Information System (INIS)

Alizadeh, R.; Ostrovski, O.

2011-01-01

Reduction of the Titanium dioxide, TiO 2 , by methane was investigated in this work. The thermodynamic of reaction was examined and found favorable. The reaction of titanium dioxide with methane was carried out in the temperature range 1150 d egree C to 1450 d egree C at atmospheric pressure with industrial high porosity pellets prepared from titanium dioxide powder. The evolved gas analyzing method was used for determination of the extent of reduction rate. The gas products of the reaction are mostly CO and trace amount of CO 2 and H 2 O. The synthesized product powder was characterized by X-ray diffraction for elucidating solid phase compositions. The effect of varying temperature was studied during the reduction. The conversion-time data have been interpreted by using the grain model. For first order reaction with respect to methane concentration, the activation energy of titanium dioxide reduction by methane is found to be 51.4 kcal/g mole. No detailed investigation of kinetic and mechanism of the reaction was reported in literatures.

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants.

Science.gov (United States)

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

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

Directory of Open Access Journals (Sweden)

Tamás Zoltán Agócs

2016-12-01

Full Text Available 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

Chemical changes of titanium and titanium dioxide under electron bombardment

Directory of Open Access Journals (Sweden)

Romins Brasca

2007-09-01

Full Text Available The electron induced effect on the first stages of the titanium (Ti0 oxidation and titanium dioxide (Ti4+ chemical reduction processes has been studied by means of Auger electron spectroscopy. Using factor analysis we found that both processes are characterized by the appearance of an intermediate Ti oxidation state, Ti2O3 (Ti3+.

Method for synthesis of titanium dioxide nanotubes using ionic liquids

Science.gov (United States)

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.

Thermal and mechanical properties of polypropylene/titanium dioxide nanocomposite fibers

International Nuclear Information System (INIS)

Esthappan, Saisy Kudilil; Kuttappan, Suma Kumbamala; Joseph, Rani

2012-01-01

Highlights: ► Wet synthesis method was used for the synthesis of TiO 2 nano particles. ► Mechanical properties of polypropylene fibers were increased by the addition of TiO 2 nanoparticles. ► Thermal stability of polypropylene fiber was improved significantly by the addition of TiO 2 nano particles. ► TiO 2 nanoparticles dispersed well in polypropylene fibers. -- Abstract: Titanium dioxide nanoparticles were prepared by wet synthesis method and characterized by transmission electron microscopy and X-ray diffraction studies. The nanotitanium dioxide then used to prepare polypropylene/titanium dioxide composites by melt mixing method. It was then made into fibers by melt spinning and subsequent drawing. Mechanical properties of the fibers were studied using Favimat tensile testing machine with a load cell of 1200 cN capacity. Thermal behavior of the fibers was studied using differential scanning calorimetry and thermogravimetric analysis. Scanning electron microscope studies were used to investigate the titanium dioxide surface morphology and crosssection of the fiber. Mechanical properties of the polypropylene fiber was improved by the addition of titanium dioxide nanoparticles. Incorporation of nanoparticles improves the thermal stability of polypropylene. Differential scanning calorimetric studies revealed an improvement in crystallinity was observed by the addition of titanium dioxide nanoparticles.

Imitation of phase I oxidative metabolism of anabolic steroids by titanium dioxide photocatalysis.

Science.gov (United States)

Ruokolainen, Miina; Valkonen, Minna; Sikanen, Tiina; Kotiaho, Tapio; Kostiainen, Risto

2014-12-18

The aim of this study was to investigate the feasibility of titanium dioxide (TiO2) photocatalysis for oxidation of anabolic steroids and for imitation of their phase I metabolism. The photocatalytic reaction products of five anabolic steroids were compared to their phase I in vitro metabolites produced by human liver microsomes (HLM). The same main reaction types - hydroxylation, dehydrogenation and combination of these two - were observed both in TiO2 photocatalysis and in microsomal incubations. Several isomers of each product type were formed in both systems. Based on the same mass, retention time and similarity of the product ion spectra, many of the products observed in HLM reactions were also formed in TiO2 photocatalytic reactions. However, products characteristic to only either one of the systems were also formed. In conclusion, TiO2 photocatalysis is a rapid, simple and inexpensive method for imitation of phase I metabolism of anabolic steroids and production of metabolite standards. Copyright © 2014 Elsevier B.V. All rights reserved.

2D-Titanium dioxide nanosheets modified with Nd, Ag and Au: Preparation, characterization and photocatalytic activity

Czech Academy of Sciences Publication Activity Database

Pližingrová, Eva; Klementová, Mariana; Bezdička, Petr; Boháček, Jaroslav; Barbieriková, Z.; Dvoranová, D.; Mazúr, M.; Krýsa, J.; Šubrt, Jan; Brezová, V.

2017-01-01

Roč. 281, MAR (2017), s. 165-180 ISSN 0920-5861 R&D Projects: GA ČR(CZ) GA14-20744S; GA MŠk(CZ) 7AMB14SK178 Institutional support: RVO:61388980 Keywords : Modified titanium dioxide * Photocatalysis * Plasmonic effect * EPR spectroscopy * Lyophilization * Spin trapping Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 4.636, year: 2016

Nanosized TiO[subscript 2] for Photocatalytic Water Splitting Studied by Oxygen Sensor and Data Logger

Science.gov (United States)

Zhang, Ruinan; Liu, Song; Yuan, Hongyan; Xiao, Dan; Choi, Martin M. F.

2012-01-01

Photocatalytic water splitting by semiconductor photocatalysts has attracted considerable attention in the past few decades. In this experiment, nanosized titanium dioxide (nano-TiO[subscript 2]) particles are used to photocatalytically split water, which is then monitored by an oxygen sensor. Sacrificial reagents such as organics (EDTA) and metal…

Degradation of orange dyes and carbamazepine by soybean peroxidase immobilized on silica monoliths and titanium dioxide.

Science.gov (United States)

Calza, Paola; Zacchigna, Dario; Laurenti, Enzo

2016-12-01

In this paper, the removal of three common dyes (orange I, orange II, and methylorange) and of the anticonvulsant drug carbamazepine from aqueous solutions by means of enzymatic and photocatalytic treatment was studied. Soybean peroxidase (SBP) was used as biocatalyst, both free in solution and immobilized on silica monoliths, and titanium dioxide as photocatalyst. The combination of the two catalysts led to a faster (about two to four times) removal of all the orange dyes compared to the single systems. All the dyes were completely removed within 2 h, also in the presence of immobilized SBP. As for carbamazepine, photocatalytic treatment prevails on the enzymatic degradation, but the synergistic effect of two catalysts led to a more efficient degradation; carbamazepine's complete disappearance was achieved within 60 min with combined system, while up to 2 h is required with TiO 2 only.

Titanium Dioxide Nanoparticles in Food and Personal Care Products

Science.gov (United States)

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 (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

Passivation of Titanium Oxide in Polyethylene Matrices using Polyelectrolytes as Titanium Dioxide Surface Coating

Directory of Open Access Journals (Sweden)

Javier Vallejo-Montesinos

2017-05-01

Full Text Available One of the major challenges of the polyolefins nowadays is the ability of those to resist weathering conditions, specially the photodegradation process that suffer any polyolefin. A common way to prevent this, is the use of hindered amine light stabilizers (HALS are employed. An alternative route to avoid photodegradation is using polyelectrolites as coating of fillers such as metal oxides. Composites of polyethylene were made using titanium dioxide (TiO2 as a filler with polyelectrolytes (polyethylenimine and sodium polystyrene sulfonate attached to its surface, to passivate its photocatalytic activity. We exposed the samples to ultraviolet-visible (UV-Vis light to observe the effect of radiation on the degradation of coated samples, compared to those without the polyelectrolyte coating. From the experimental results, we found that polyethylenimine has a similar carbonyl signal area to the sample coated with hindered amine light stabilizers (HALS while sodium polystyrene sulfonate exhibit more degradation than the HALS coated samples, but it passivates the photocatalytic effect when compared with the non-coated TiO2 samples. Also, using AFM measurements, we confirmed that the chemical nature of polyethylenimine causes the TiO2 avoid the migration to the surface during the extrusion process, inhibiting the photodegradation process and softening the sample. On this basis, we found that polyethylenimine is a good choice for reducing the degradation caused by TiO2 when it is exposed to UV-Vis light.

Interaction of titanium and vanadium with carbon dioxide under heating

International Nuclear Information System (INIS)

Vlasyuk, R.Z.; Kurovskij, V.Ya.; Lyapunov, V.P.; Radomysel'skij, I.D.

1986-01-01

The methods of gravitmetric and X-ray phase analysis as well as analysis of composition of gases in the heating chamber have been used to investigate the mechanism of titanium and vanadium interaction with carbon dioxide in the 300-1000 deg C temperature range. The analogy of mechanisms of the interaction of titanium and vanadium with carbon dioxide in oxides production on the metal surface with subsequent carbidizing treatment at temperatures above 800 deg C is shown. Temperature limits of material operation on the base of titanium or vanadium in carbon dioxide must not exceed 400 or 600 deg C, respectively

Photocatalytic hydrogen production on SOLECTRO {sup registered} titanium dioxide layers. Development and characterization of an efficient catalyst; Photokatalytische Wasserstoffgewinnung an SOLECTRO {sup registered} -Titandioxidschichten. Entwicklung und Charakterisierung eines geeigneten Katalysators

Energy Technology Data Exchange (ETDEWEB)

Saborowski, Sarah

2010-03-03

A catalyst for photocatalytic hydrogen production from methanol and water was developed on the basis of SOLECTRO {sup registered} titanium dioxide layers. A test facility was constructed in which several modified catalysts could be tested for this reaction. Detailed characterization of the electronic and optical characteristics of these catalysts made it possible to gain deeper insight into the processes involved in the reaction. (orig.) [German] Auf Basis der SOLECTRO {sup registered} -TiO{sub 2} -Schichten wurde ein Katalysator fuer die photokatalytische Wasserstoffdarstellung aus Methanol und Wasser entwickelt. Der Aufbau einer geeigneten Versuchsanlage ermoeglichte es, verschieden modifizierte Katalysatoren fuer diese Reaktion zu testen. Durch die ausfuehrliche Charakterisierung insbesondere der elektronischen und optischen Eigenschaften dieser Katalysatoren konnten vertiefende Erkenntnisse zu den waehrend der Reaktion ablaufenden Prozessen gewonnen werden. (orig.)

A short review on photocatalytic degradation of formaldehyde

NARCIS (Netherlands)

Tasbihi, M.; Bendyna, J.K.; Notten, P.H.L.; Hintzen, H.T.J.M.

2015-01-01

Nowadays, it is a great challenge to eliminate toxic and harmful organic pollutants from air and water. This paper reviews the role of TiO2 as a photocatalyst, light source and photoreactor in the particular case of removal of formaldehyde using the photocatalytic reaction by titanium dioxide (TiO2

Growth of anatase titanium dioxide nanotubes via anodization

Directory of Open Access Journals (Sweden)

Ed Adrian Dilla

2012-06-01

Full Text Available In this work, titanium dioxide nanotubes were grown via anodization of sputtered titanium thin films using different anodization parameters in order to formulate a method of producing long anatase titanium dioxide nanotubes intended for solar cell applications. The morphological features of the nanotubes grown via anodization were explored using a Philips XL30 Field Emission Scanning Electron Microscope. Furthermore, the grown nanotubes were also subjected to X-ray diffraction and Raman spectroscopy in order to investigate the effect of the predominant crystal orientation of the parent titanium thin film on the crystal phase of the nanotubes. After optimizing the anodization parameters, nanotubes with anatase TiO2 crystal phase and tube length more than 2 microns was produced from parent titanium thin films with predominant Ti(010 crystal orientation and using ammonium fluoride in ethylene glycol as an electrolyte with a working voltage equal to 60V during 1-hour anodization runs.

Titanium dioxide nanoparticles: some aspects of toxicity/focus on the development.

Science.gov (United States)

Rollerova, E; Tulinska, J; Liskova, A; Kuricova, M; Kovriznych, J; Mlynarcikova, A; Kiss, A; Scsukova, S

2015-04-01

Nanosized titanium dioxide (TiO2) particles belong to the most widely manufactured nanoparticles (NPs) on a global scale because of their photocatalytic properties and the related surface effects. TiO2 NPs are in the top five NPs used in consumer products. Ultrafine TiO2 is widely used in the number of applications, including white pigment in paint, ceramics, food additive, food packaging material, sunscreens, cosmetic creams, and, component of surgical implants. Data evidencing rapid distribution, slow or ineffective elimination, and potential long-time tissue accumulation are especially important for the human risk assessment of ultrafine TiO2 and represent new challenges to more responsibly investigate potential adverse effects by the action of TiO2 NPs considering their ubiquitous exposure in various doses. Transport of ultrafine TiO2 particles in systemic circulation and further transition through barriers, especially the placental and blood-brain ones, are well documented. Therefore, from the developmental point of view, there is a raising concern in the exposure to TiO2 NPs during critical windows, in the pregnancy or the lactation period, and the fact that human mothers, women and men in fertile age and last but not least children may be exposed to high cumulative doses. In this review, toxicokinetics and particularly toxicity of TiO2 NPs in relation to the developing processes, oriented mainly on the development of the central nervous system, are discussed Keywords: nanoparticles, nanotoxicity, nanomaterials, titanium dioxide, reproductive toxicity, developmental toxicity, blood brain barrier, placental barrier.

NOx photocatalytic degradation employing concrete pavement containing titanium dioxide

NARCIS (Netherlands)

Ballari, M.M.; Hunger, Martin; Hüsken, Götz; Brouwers, Jos

2010-01-01

In the present work the degradation of nitrogen oxides (NOx) by concrete paving stones containing TiO2 to be applied in road construction is studied. A kinetic model is proposed to describe the photocatalytic reaction of NOx (combining the degradation of NO and the appearance and disappearance of

Photocatalytic degradation of dairy effluent using AgTiO2 nanostructures/polyurethane nanofiber membrane

DEFF Research Database (Denmark)

Kanjwal, Muzafar Ahmad; Barakat, Nasser A.M.; Chronakis, Ioannis S.

2015-01-01

Dairy effluent (DE) is environmentally toxic and needs special attention. Photocatalytic degradation of DE was studied using novel polyurethane (PU)-based membranes. Typically, silver-titanium dioxide nanofibers (AgTiO2 NFs) and silver-titanium dioxide nanoparticles (AgTiO2 NPs) were individually...... incorporated in PU electrospun nanofibers to overcome the mandatory sophisticated separation of the nanocatalysts, which can create a secondary pollution, after the treatment process. These nanomembranes were characterized in SEM, TEM, XRD and UV studies. The polymeric electrospun nanofibers were smooth...

Facile hydrothermal preparation of titanium dioxide decorated reduced graphene oxide nanocomposite

Science.gov (United States)

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

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

Science.gov (United States)

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.

Laboratory and field studies of photocatalytic NOx and O3 removal by coatings on concrete.

Science.gov (United States)

2017-03-01

This project involved thorough testing of titanium dioxide (TiO2)-containing commercial photocatalytic coatings : applied to portland cement concrete for highway applications, focusing on the use of these coatings as an : abatement method for atmosph...

Photocatalytic and chemical oxidation of organic compounds in supercritical carbon dioxide. 1998 annual progress report

International Nuclear Information System (INIS)

Blake, D.M.

1998-01-01

'This report summarizes the results of work done during the first 1.3 years of a three year project. During the first nine months effort focussed on the design, construction and testing of a closed recirculating system that can be used to study photochemistry in supercritical carbon dioxide at pressures up to 5,000 psi and temperatures up to about 50 C. This was followed by a period of work in which the photocatalytic oxidation of benzene and acetone in supercritical, liquid, and gaseous carbon dioxide containing dissolved oxygen was demonstrated. The photocatalyst was titanium dioxide supported on glass spheres. This was the first time it was possible to observe photocatalytic oxidation in a supercritical fluid and to compare reaction in the three fluid phases of a solvent. This also demonstrated that it is possible to purify supercritical and liquid carbon dioxide using photochemical oxidation with no chemical additions other than oxygen. The oxidation of benzene produced no intermediates detectable using on line spectroscopic analysis or by gas chromatographic analysis of samples taken from the flow system. The catalyst surface did darken as the reaction proceeded indicating that oxidation products were accumulating on the surface. This is analogous to the behavior of aromatic compounds in air phase photocatalytic oxidation. The reaction of acetone under similar conditions resulted in the formation of low levels of by-products. Two were identified as products of the reaction of acetone with itself (4-methyl-3-penten-2-one and 4-hydroxy-4-methyl-2-pentanone) using gas chromatography with a mass spectrometer detector. Two other by-products also appear to be from the self-reaction of acetone. By-products of this type had not been observed in prior studies of the gas-phase photocatalytic oxidation of acetone. The by-products that have been observed can also be oxidized under the treatment conditions. The above results establish that photocatalytic oxidation of

Clinical and histomorphometrical study on titanium dioxide-coated external fixation pins

Directory of Open Access Journals (Sweden)

Koseki H

2013-02-01

Full Text Available Hironobu Koseki,1 Tomohiko Asahara,1 Takayuki Shida,1 Itaru Yoda,1 Hidehiko Horiuchi,1 Koumei Baba,2 Makoto Osaki11Department of Orthopedic Surgery, Graduate School of Medicine, Nagasaki University, 2Industrial Technology Center of Nagasaki, Nagasaki, JapanBackground: Pin site infection is the most common and significant complication of external fixation. In this work, the efficacy of pins coated with titanium dioxide (TiO2 for inhibition of infection was compared with that of stainless steel control pins in an in vivo study.Methods: Pins contaminated with an identifiable Staphylococcus aureus strain were inserted into femoral bone in a rat model and exposed to ultraviolet A light for 30 minutes. On day 14, the animals were sacrificed and the bone and soft tissue around the pin were retrieved. The clinical findings and histological findings were evaluated in 60 samples.Results: Clinical signs of infection were present in 76.7% of untreated pins, but in only 36.7% of TiO2-coated pins. The histological bone infection score and planimetric rate of occupation for bacterial colonies and neutrophils in the TiO2-coated pin group were lower than those in the control group. The bone-implant contact ratio of the TiO2-coated pin group was significantly higher (71.4% than in the control pin group (58.2%. The TiO2 was successful in decreasing infection both clinically and histomorphometrically.Conclusion: The photocatalytic bactericidal effect of TiO2 is thought to be useful for inhibiting pin site infection after external fixation.Keywords: titanium dioxide, external fixation, bactericidal activity, Staphylococcus aureus

Surface Modification of Silica Nanoparticles with Titanium Tetraisopropoxide and Evaluation of their Photocatalytic Activity

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Leila Mazaheri

2012-12-01

Full Text Available Silica nanoparticles were modified with titanium tetraisopropoxide (TTIP via atwo-step sol-gel route. The modified silica nanoparticles were characterized using FTIR spectroscopy, thermal gravimetric analysis (TGA and EDAX elemental analysis. Photocatalytic activity of the modified nanocomposites was evaluated by photo-activated degradation of Rhodamine B (Rh.B dyestuff, as a colorant model, in distilled water. Reduction in Rh.B concentration in aqueous solution was evaluated by UV-visible spectroscopy and with the aid of visual observations. The FTIR spectroscopy results confirmed the formation of Ti-O-Si chemical bond on the surfaceof silica nanoparticles. TGA test results showed that the weight loss of the modified sample is due to deterioration of the alkoxy groups of the SiO2 surface. According to the results of EDAX elemental analysis, the presence of carbon and titanium in the structure of the modified samples and also reduction in oxygen levels are attributed to the chemical interactions due to surface chemical modification. Carbon detection in the composition can be attributed to the presence of isopropoxide in titanium tetraisopropoxide compound. The results also revealed that, with TiO2 grafting on the silica nanoparticles surface, absorption in UV region is increased and that the silica nanoparticles modified with titanate compound show photocatalytic characteristics and degradation ability of Rh.B dyestuff under UV light irradiation. It became also evident that the photocatalytic activity of the modified nanoparticles is less than TiO2 nanoparticles. However, by inclusion of modified silica nanoparticles into the polymeric coating, the photocatalytic properties of the coating can be established. Although modified silica nanoparticles have less photocatalytic activity compared to TiO2 nanoparticles, but they cause less damage to the polymer matrix.

The effect of electrolytes on the aggregation kinetics of titanium dioxide nanoparticle aggregates

International Nuclear Information System (INIS)

Shih Yanghsin; Zhuang Chengming; Tso Chihping; Lin Chenghan

2012-01-01

Metal oxide nanoparticles (NPs) are receiving increasing attention due to their increased industrial production and potential hazardous effect. The process of aggregation plays a key role in the fate of NPs in the environment and the resultant health risk. The aggregation of commercial titanium dioxide NP powder (25 nm) was investigated with various environmentally relevant solution chemistries containing different concentrations of monovalent (Na + , K + ) and divalent (Ca 2+ ) electrolytes. Titanium dioxide particle size increased with the increase in ion concentration. The stability of titanium dioxide also depended on the ionic composition. Titanium dioxide aggregated to a higher degree in the presence of divalent cations than monovalent ones. The attachment efficiency of NPs was constructed through aggregation kinetics data, from which the critical coagulation concentrations for the various electrolytes are determined (80, 19, and 1 meq/L for Na + , K + , and Ca 2+ , respectively). Our results suggest that titanium dioxide NP powders are relatively unstable in water and could easily be removed by adding multivalent cations so hazardous potentials decrease in aquatic environment.

Measuring the Photocatalytic Breakdown of Crystal Violet Dye using a Light Emitting Diode Approach

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Ryan, Robert E.; Underwood, Lauren W.; O'Neal, Duane; Pagnutti, Mary; Davis, Bruce A.

2009-01-01

A simple method to estimate the photocatalytic reactivity performance of spray-on titanium dioxide coatings for transmissive glass surfaces was developed. This novel technique provides a standardized method to evaluate the efficiency of photocatalytic material systems over a variety of illumination levels. To date, photocatalysis assessments have generally been conducted using mercury black light lamps. Illumination levels for these types of lamps are difficult to vary, consequently limiting their use for assessing material performance under a diverse range of simulated environmental conditions. This new technique uses an ultraviolet (UV) gallium nitride (GaN) light emitting diode (LED) array instead of a traditional black light to initiate and sustain photocatalytic breakdown. This method was tested with a UV-resistant dye (crystal violet) applied to a titanium dioxide coated glass slide. Experimental control is accomplished by applying crystal violet to both titanium dioxide coated slides and uncoated control slides. A slide is illuminated by the UV LED array, at various light levels representative of outdoor and indoor conditions, from the dye side of the slide. To monitor degradation of the dye over time, a temperature-stabilized white light LED, whose emission spectrum overlaps with the dye absorption spectrum, is used to illuminate the opposite side of the slide. Using a spectrometer, the amount of light from the white light LED transmitted through the slide as the dye degrades is monitored as a function of wavelength and time and is subsequently analyzed. In this way, the rate of degradation for photocatalytically coated versus uncoated slide surfaces can be compared. Results demonstrate that the dye absorption decreased much more rapidly on the photocatalytically coated slides than on the control uncoated slides, and that dye degradation is dependent on illumination level. For photocatalytic activity assessment purposes, this experimental configuration and

Phase study of titanium dioxide nanoparticle prepared via sol-gel process

Science.gov (United States)

Oladeji Araoyinbo, Alaba; Bakri Abdullah, Mohd Mustafa Al; Salleh, Mohd Arif Anuar Mohd; Aziz, Nurul Nadia Abdul; Iskandar Azmi, Azwan

2018-03-01

In this study, titanium dioxide nanoparticles have been prepared via sol-gel process using titanium tetraisopropoxide as a precursor with hydrochloric acid as a catalyst, and ethanol with deionized water as solvents. The value of pH used is set to 3, 7 and 8. The sols obtained were dried at 100 °C for 1 hr and calcined at 350, 550, and 750 °C for 3 hrs to observe the phase transformation of titanium dioxide nanoparticle. The samples were characterized by x-ray diffraction and field emission scanning electron microscope. The morphology analysis is obtained from field emission scanning electron microscope. The phase transformation was investigated by x-ray diffraction. It was found that the pH of the solution affect the agglomeration of titanium dioxide particle. The x-ray diffraction pattern of titanium dioxide shows the anatase phase most abundant at temperature of 350 °C. At temperature of 550 °C the anatase and rutile phase were present. At temperature of 750 °C the rutile phase was the most abundant for pH 3, 7 and 8. It was confirmed that at higher temperature the rutile phase which is the stable phase are mostly present.

Titanium dioxide nanoparticles induce oxidative stress and DNA-adduct formation but not DNA-breakage in human lung cells

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Schins Roel PF

2009-06-01

Full Text Available Abstract Titanium dioxide (TiO2, also known as titanium (IV oxide or anatase, is the naturally occurring oxide of titanium. It is also one of the most commercially used form. To date, no parameter has been set for the average ambient air concentration of TiO2 nanoparticles (NP by any regulatory agency. Previously conducted studies had established these nanoparticles to be mainly non-cyto- and -genotoxic, although they had been found to generate free radicals both acellularly (specially through photocatalytic activity and intracellularly. The present study determines the role of TiO2-NP (anatase, ∅ in vitro. For comparison, iron containing nanoparticles (hematite, Fe2O3, ∅ 2-NP did not induce DNA-breakage measured by the Comet-assay in both cell types. Generation of reactive oxygen species (ROS was measured acellularly (without any photocatalytic activity as well as intracellularly for both types of particles, however, the iron-containing NP needed special reducing conditions before pronounced radical generation. A high level of DNA adduct formation (8-OHdG was observed in IMR-90 cells exposed to TiO2-NP, but not in cells exposed to hematite NP. Our study demonstrates different modes of action for TiO2- and Fe2O3-NP. Whereas TiO2-NP were able to generate elevated amounts of free radicals, which induced indirect genotoxicity mainly by DNA-adduct formation, Fe2O3-NP were clastogenic (induction of DNA-breakage and required reducing conditions for radical formation.

Preparation and elementary research on electrocatalytic hydrogen evolution of highly ordered titanium dioxide nanotube arrays

International Nuclear Information System (INIS)

Wu Qinglong; Liao Junsheng; Bai Yun

2010-01-01

Well ordered and uniform titanium dioxide nanotube arrays were fabricated by anodiaing process from a bath containing 1% NaF, 1mol/L Na 2 SO 4 , 0.5 mol/L H 2 SO 4 at room temperature. Surface morphology of titanium dioxide nanotube arrays were observed with SEM. The formation process of titanium dioxide nanotube arrays was suggested by current-time transient. Its catalytic hydrogen evolution behavior was studied by electrochemical measurements in a 5%(mass fraction) H 2 SO 4 solution. The results showed that the titanium dioxide nanotube arrays on titanium had better hydrogen evolution activity and trace palladium lead to the maximum electrocatalytic activity of hydrogen production. (authors)

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

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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.

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

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- 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...

Photocatalytic equipment with nitrogen-doped titanium dioxide for air cleaning and disinfecting

International Nuclear Information System (INIS)

Le, Thanh Son; Ngo, Quoc Buu; Nguyen, Viet Dung; Nguyen, Hoai Chau; Dao, Trong Hien; Tran, Xuan Tin; Kabachkov, E N; Balikhin, I L

2014-01-01

Nitrogen-doped TiO 2 nanoparticle photocatalysts were synthesized by a sol–gel procedure using tetra-n-butyl orthotitanate as a titanium precursor and urea as a nitrogen source. Systematic studies for the preparation parameters and their impact on the material's structure were carried out by multiple techniques: thermogravimetric and differential scanning calorimetric analysis, x-ray diffraction, scanning electron microscope, transmission electron microscopy, energy dispersive x-ray spectroscopy and UV–Vis diffuse reflectance spectrophotometry showed that the nitrogen-doped TiO 2 calcined at 500 °C for 3 h exhibited a spherical form with a particle size about 15–20 nm and crystal phase presented a mixture of 89.12% anatase. The obtained product was deposited on a porous quartz tube (D = 74 mm; l = 418 mm) to manufacture an air photocatalytic cleaner as a prototype of the TIOKRAFT company's equipment. The created air cleaner was able to remove 60% of 10 ppm acetone within 390 min and degrade 98.5% of bacteria (total aerobic bacteria and fungi, 300 cfu m −3 ) within 120 min in a 10 m 3 box. These photodegradation activities of N-TiO 2 are higher than that of the commercial nano-TiO 2 (Skyspring Inc., USA, particle size of 5–10 nm). (paper)

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

Science.gov (United States)

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...

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

Science.gov (United States)

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.

The microstructure and properties of titanium dioxide films synthesized by unbalanced magnetron sputtering

International Nuclear Information System (INIS)

Leng, Y.X.; Chen, J.Y.; Yang, P.; Sun, H.; Huang, N.

2007-01-01

In this work, titanium oxide films were deposited on Ti6Al4V and Si (1 0 0) by DC unbalanced magnetron sputtering method at different oxygen pressure. X-ray diffraction (XRD), microhardness tests, pin-on-disk wear experiments, surface contact angle tests and platelet adhesion investigation were conducted to evaluate the properties of the films. The corrosion behavior of titanium dioxide films was characterized by potentiodynamic polarization. The results showed that titanium oxide films deposited by unbalance magnetron sputtering were compact and could obviously enhance microhardness, wear resistance of titanium alloy substrate. Potentiodynamic polarization curves showed that Ti-6Al-4V deposited with titanium dioxide films had lower dissolution currents than that of the uncoated one. The results of in vitro hemocompatibility analyses indicated that the blood compatibility of the titanium dioxide films with bandgap 3.2 eV have better blood compatibility

Mesoporous titanium dioxide (TiO2) with hierarchically 3D dendrimeric architectures: formation mechanism and highly enhanced photocatalytic activity.

Science.gov (United States)

Li, Xiao-Yun; Chen, Li-Hua; Rooke, Joanna Claire; Deng, Zhao; Hu, Zhi-Yi; Wang, Shao-Zhuan; Wang, Li; Li, Yu; Krief, Alain; Su, Bao-Lian

2013-03-15

Mesoporous TiO(2) with a hierarchically 3D dendrimeric nanostructure comprised of nanoribbon building units has been synthesized via a spontaneous self-formation process from various titanium alkoxides. These hierarchically 3D dendrimeric architectures can be obtained by a very facile, template-free method, by simply dropping a titanium butoxide precursor into methanol solution. The novel configuration of the mesoporous TiO(2) nanostructure in nanoribbon building units yields a high surface area. The calcined samples show significantly enhanced photocatalytic activity and degradation rates owing to the mesoporosity and their improved crystallinity after calcination. Furthermore, the 3D dendrimeric architectures can be preserved after phase transformation from amorphous TiO(2) to anatase or rutile, which occurs during calcination. In addition, the spontaneous self-formation process of mesoporous TiO(2) with hierarchically 3D dendrimeric architectures from the hydrolysis and condensation reaction of titanium butoxide in methanol has been followed by in situ optical microscopy (OM), revealing the secret on the formation of hierarchically 3D dendrimeric nanostructures. Moreover, mesoporous TiO(2) nanostructures with similar hierarchically 3D dendrimeric architectures can also be obtained using other titanium alkoxides. The porosities and nanostructures of the resultant products were characterized by SEM, TEM, XRD, and N(2) adsorption-desorption measurements. The present work provides a facile and reproducible method for the synthesis of novel mesoporous TiO(2) nanoarchitectures, which in turn could herald the fabrication of more efficient photocatalysts. Copyright © 2012 Elsevier Inc. All rights reserved.

Photocatalytic activity of titanium dioxide modified by Fe2O3 nanoparticles

International Nuclear Information System (INIS)

Wodka, Dawid; Socha, Robert P.; Bielańska, Elżbieta; Elżbieciak-Wodka, Magdalena; Nowak, Paweł; Warszyński, Piotr

2014-01-01

Highlights: • 1% Fe 2 O 3 /TiO 2 composite showing high activity in the photocatalytic oxidation of organics was synthetized. • Electrochemical analysis indicated that surface modification of Degussa P25 by Fe 2 O 3 causes the appearance of surface states in such a material. • The enhanced activity of the prepared composite may be ascribed to the occurrence of the photo-Fenton process. - Abstract: Photocatalytic activity of Fe 2 O 3 /TiO 2 composites obtained by precipitation was investigated. The composite material containing 1.0 wt% of iron(III) oxide nanoparticles was obtained by depositing Fe 2 O 3 on the Evonic-Degussa P25 titania surface. SEM, XPS, DRS, CV and EIS techniques were applied to examine synthetized pale orange photocatalyst. The XPS measurements revealed that iron is present mainly in the +3 oxidation state but iron in the +2 oxidation state can be also detected. Electrochemical analysis indicated that surface modification of Degussa P25 by Fe 2 O 3 causes the appearance of surface states in such a material. Nevertheless, based on the DRS measurement it was shown that iron(III) oxide nanoparticles modified the P25 spectral properties but they did not change the band gap width. The photocatalytic activity of Fe 2 O 3 /TiO 2 composite was compared to photocatalytic activity of pristine P25 in photooxidation reaction of model compounds: oxalic acid (OxA) and formic acid (FA). Photodecomposition reaction was investigated in a batch reactor containing aqueous suspension of a photocatalyst illuminated by either UV or artificial sunlight (halogen lamp). The tests proved that nanoparticles deposited on titania surface triggers the increase in photocatalytic activity, this increase depends however on the decomposed substance

Structure and amphoteric properties of titanium dioxide gels

International Nuclear Information System (INIS)

Kertesz, C.

1991-01-01

Mechanisms responsible for the in-solution ion retention by titanium dioxide are studied. Mineral oxide gel formation and structure are described and various titanium dioxide gel synthesis modes are presented. A two-phase model, taking into account the porous nature of the solid and allowing for the application of the mass action law, is adopted. The oxide amphoteric properties are studied with the potentiometric titration technique. Hysteresis loops are imputed to the slowness of the acid-basic neutralization reaction. The main characteristics are determined: isoelectric point, cation and anion retention capacity. Depending on the suspension agitation, the speed limiting factor may be the diffusion in the film or the diffusion in the particle. 60 fig., 128 ref

Titanium dioxide. An effective additive for minimisation of alkali vaporisation; Titandioxidadditiv. En effektiv tillsats foer att minska alkalifoeraangning

Energy Technology Data Exchange (ETDEWEB)

Wiinikka, Henrik; Groenberg, Carola; Oehrman, Olov

2008-10-15

If an additive of titanium dioxide can limit the release of alkali under practical combustion conditions it may significantly reduce the ash related operational problems in real furnaces. The aim with this project is therefore to investigate if an additive of titanium dioxide could reduce the vaporisation of alkali during practical combustion conditions and determine the optimum mixing ratio between the fuel and titanium dioxide. Controlled combustion experiments with varied amounts of titanium dioxide in straw pellets were performed in a pellet burner together with sampling of particles in the flue gas (impactor and absolute filter), analysis of the flue gas composition (FTIR) and chemical analyses of the collected particles and bottom ashes (ICP, SEM/EDS, and XRD). The experimental results from this study showed that an increasing amount of titanium dioxide additive reduced the concentration of fine particles in the flue gas. The particle concentration was reduced from 241 mg/Nm3 to 163 mg/Nm3 for an optimum amount of titanium dioxide additive. Furthermore, the concentration of HCl and SO{sub 2} in the flue gas increased when the titanium dioxide was introduced to the straw pellets. Independent of titanium dioxide additive or not, no titanium was detected in the submicron particles. This indicates that titanium is a refractory element that is not vaporised during the combustion process. The chemical composition of the flue gas particles was also influenced by titanium dioxide additive. In general, the amounts of O, Na, and P were increased in the same time as the amounts of S, Cl, and K were reduced when more titanium dioxide was introduced to the straw pellets. From the particle concentration in the flue gas and the chemical composition of the fine particles, the particle bound elemental concentration of Na, P, S, Cl, and K could be estimated. From this investigation the concentration of potassium in the flue gas was reduced from 126 mg/Nm3 to 77 mg/Nm3 when

A Study on Kaolin and Titanium dioxide affecting Physical Properties of Electrocoating

International Nuclear Information System (INIS)

Yang, Wonseog; Hwang, Woonsuk

2013-01-01

The electrocoating for automotive bodies is pigmented with a mixture of titanium dioxide and kaolin. In this study, the effects of titanium dioxide and kaolin contents in coating on electrodeposition process, drying, and surface properties such as surface roughness, gloss, impact resistance and corrosion resistance were investigated. Titanium dioxide and kaolin in coating do not have a decisive effect on curing reaction during drying and corrosion resistance but on gloss, surface roughness, impact resistance and electrodeposition process of coating. According to its size and shape on coating surface, pigment contents increased during drying process. However, the contents of kaolin and TiO 2 in coating didn't affect the corrosion resistance on zinc phosphated substrate, and the curing properties

Homogenous photocatalytic decontamination of prion infected stainless steel and titanium surfaces.

Science.gov (United States)

Berberidou, Chrysanthi; Xanthopoulos, Konstantinos; Paspaltsis, Ioannis; Lourbopoulos, Athanasios; Polyzoidou, Eleni; Sklaviadis, Theodoros; Poulios, Ioannis

2013-01-01

Prions are notorious for their extraordinary resistance to traditional methods of decontamination, rendering their transmission a public health risk. Iatrogenic Creutzfeldt-Jakob disease (iCJD) via contaminated surgical instruments and medical devices has been verified both experimentally and clinically. Standard methods for prion inactivation by sodium hydroxide or sodium hypochlorite have failed, in some cases, to fully remove prion infectivity, while they are often impractical for routine applications. Prion accumulation in peripheral tissues and indications of human-to-human bloodborne prion transmission, highlight the need for novel, efficient, yet user-friendly methods of prion inactivation. Here we show both in vitro and in vivo that homogenous photocatalytic oxidation, mediated by the photo-Fenton reagent, has the potential to inactivate the pathological prion isoform adsorbed on metal substrates. Photocatalytic oxidation with 224 μg mL(-1) Fe (3+), 500 μg mL(-1) h(-1) H 2O 2, UV-A for 480 min lead to 100% survival in golden Syrian hamsters after intracranial implantation of stainless steel wires infected with the 263K prion strain. Interestingly, photocatalytic treatment of 263K infected titanium wires, under the same experimental conditions, prolonged the survival interval significantly, but failed to eliminate infectivity, a result that we correlate with the increased adsorption of PrP(Sc) on titanium, in comparison to stainless steel. Our findings strongly indicate that our, user--and environmentally--friendly protocol can be safely applied to the decontamination of prion infected stainless steel surfaces.

The use of titanium dioxide micro-columns to selectively isolate phosphopeptides from proteolytic digests

DEFF Research Database (Denmark)

Thingholm, Tine E; Larsen, Martin R

2009-01-01

Titanium dioxide has very high affinity for phosphopeptides and it has become an efficient alternative to already existing methods for phosphopeptide enrichment from complex samples. Peptide loading in a highly acidic environment in the presence of 2,5-dihydroxybenzoic acid (DHB), phthalic acid......, or glycolic acid has been shown to improve selectivity significantly by reducing unspecific binding from nonphosphorylated peptides. The enriched phosphopeptides bound to the titanium dioxide are subsequently eluted from the micro-column using an alkaline buffer. Titanium dioxide chromatography is extremely...... tolerant towards most buffers used in biological experiments. It is highly robust and as such it has become one of the methods of choice in large-scale phospho-proteomics. Here we describe the protocol for phosphopeptide enrichment using titanium dioxide chromatography followed by desalting...

Biotemplated Synthesis of Anatase Titanium Dioxide Nanoparticles via Lignocellulosic Waste Material

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Donya Ramimoghadam

2014-01-01

Full Text Available 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.

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

Science.gov (United States)

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.

Gas-Phase Photocatalytic Oxidation of Dimethylamine: The Reaction Pathway and Kinetics

Directory of Open Access Journals (Sweden)

Anna Kachina

2007-01-01

Full Text Available Gas-phase photocatalytic oxidation (PCO and thermal catalytic oxidation (TCO of dimethylamine (DMA on titanium dioxide was studied in a continuous flow simple tubular reactor. Volatile PCO products of DMA included ammonia, formamide, carbon dioxide, and water. Ammonia was further oxidized in minor amounts to nitrous oxide and nitrogen dioxide. Effective at 573 K, TCO resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The PCO kinetic data fit well to the monomolecular Langmuir-Hinshelwood model, whereas TCO kinetic behaviour matched the first-order process. No deactivation of the photocatalyst during the multiple long-run experiments was observed.

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

Science.gov (United States)

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.

Investigation of DC magnetron-sputtered TiO2 coatings: Effect of coating thickness, structure, and morphology on photocatalytic activity

DEFF Research Database (Denmark)

Daviðsdóttir, Svava; Shabadi, Rajashekhara; Galca, Aurelian Catalin

2014-01-01

The photocatalytic performance of magnetron-sputtered titanium dioxide (TiO2) coatings of different thickness in anatase crystalline structure deposited on aluminium 1050 alloy substrates was investigated using a combination of photo-electrochemistry, methylene blue decomposition, and microscopic...

Influences of Silver-Doping on the Crystal Structure, Morphology and Photocatalytic Activity of TiO2 Nanofibers

DEFF Research Database (Denmark)

Barakat, Nasser A. M.; Kanjwal, Muzafar Ahmed; Al-Deyab, Salem S.

2011-01-01

Doping of titanium dioxide nanofibers by silver nanoparticles revealed distinct improvement in the photocatalytic activ-ity; however other influences have not been investigated. In this work, effect of sliver-doping on the crystal structure, the nanofibrous morphology as well as the photocatalyti...

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

Science.gov (United States)

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.

Fast and Straightforward Synthesis of Luminescent Titanium(IV Dioxide Quantum Dots

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Václav Štengl

2017-01-01

Full Text Available The nucleus of titania was prepared by reaction of solution titanium oxosulphate with hydrazine hydrate. These titania nuclei were used for titania quantum dots synthesis by a simple and fast method. The prepared titanium(IV dioxide quantum dots were characterized by measurement of X-ray powder diffraction (XRD, X-ray photoelectron spectroscopy (XPS, atomic force microscopy (AFM, high-resolution electron microscopy (HRTEM, and selected area electron diffraction (SAED. The optical properties were determined by photoluminescence (PL spectra. The prepared titanium(IV dioxide quantum dots have the narrow range of UV excitation (365–400 nm and also a close range of emission maxima (450–500 nm.

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

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Diana S. Raie

2018-01-01

Full Text Available 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.

High-pressure behavior of nano titanium dioxide

DEFF Research Database (Denmark)

Olsen, J.S.; Gerward, Leif; Jiang, Jianzhong

2002-01-01

Nanocrystalline rutile Titanium dioxide has been studied by X-ray diffraction at ambient temperature up to 47.4 GPa. The material is found to transform to the monoclinic baddeleyite structure between 20 and 30 GPa, which is higher than the corresponding pressure range for bulk material. Upon deco...

SiO2@TiO2 Coating: Synthesis, Physical Characterization and Photocatalytic Evaluation

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A. Rosales

2018-03-01

Full Text Available Use of silicon dioxide (SiO2 and titanium dioxide (TiO2 have been widely investigated individually in coatings technology, but their combined properties promote compatibility for different innovative applications. For example, the photocatalytic properties of TiO2 coatings, when exposed to UV light, have interesting environmental applications, such as air purification, self-cleaning and antibacterial properties. However, as reported in different pilot projects, serious durability problems, associated with the adhesion between the substrate and TiO2, have been evidenced. Thus, the aim of this work is to synthesize SiO2 together with TiO2 to increase the durability of the photocatalytic coating without affecting its photocatalytic potential. Therefore, synthesis using sonochemistry, synthesis without sonochemistry, physical characterization, photocatalytic evaluation, and durability of the SiO2, SiO2@TiO2 and TiO2 coatings are presented. Results indicate that using SiO2 improved the durability of the TiO2 coating without affecting its photocatalytic properties. Thus, this novel SiO2@TiO2 coating shows potential for developing long-lasting, self-cleaning and air-purifying construction materials.

New Surface Aspects towards Photocatalytic Activity of Doped Supported Titanium Dioxide

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Samia A. Kosa

2016-01-01

Full Text Available The present work aims to synthesize nanoscale well dispersed TiO2/SiO2 and TiO2/Al2O3 nanoparticle photocatalysts via an impregnation method for the removal of methyl orange, which was used as a model compound of organic pollutant in wastewater, from an aqueous medium. Also within this frame work, La and Ce metals were loaded onto the surfaces of TiO2/SiO2 and TiO2/Al2O3 by an impregnation method to enhance the photocatalytic activity of the nanoparticles; the activities and physicochemical properties of the photocatalysts were compared before and after loading of metallic La and Ce. The oxide system was characterized by different techniques, including XRD, UV-Vis spectroscopy, FT-IR spectroscopy, SEM, and EDX spectroscopy. Finally, the optimal conditions to complete the photocatalytic oxidation of methyl orange dye were studied. This work holds promise for the efficient photodegradation of pollutants by nanoparticle photocatalysts.

Preparation and photocatalytic activity of B, Y co-doped nanosized TiO_2 catalyst

Institute of Scientific and Technical Information of China (English)

石中亮; 刘富梅; 姚淑华

2010-01-01

The catalysts of un-doped, single-doped and co-doped titanium dioxide (TiO2) powders were prepared by sol-gel method with Ti(OC4H9)4 as a raw material. The photocatalytic decomposition of phenol in aqueous solution under UV light was used as a probe reaction to evaluate their photocatalytic activities. The effects of B, Y co-doping on the crystallite sizes, crystal pattern, surface composition, and optical property of the catalyst were investigated by thermogravimetric differential thermal analysis, X-ray d...

Carbonate effects on hexavalent uranium removal from water by nanocrystalline titanium dioxide

International Nuclear Information System (INIS)

Wazne, Mahmoud; Meng, Xiaoguang; Korfiatis, George P.; Christodoulatos, Christos

2006-01-01

A novel nanocrystalline titanium dioxide was used to treat depleted uranium (DU)-contaminated water under neutral and alkaline conditions. The novel material had a total surface area of 329 m 2 /g, total surface site density of 11.0 sites/nm 2 , total pore volume of 0.415 cm 3 /g and crystallite size of 6.0 nm. It was used in batch tests to remove U(VI) from synthetic solutions and contaminated water. However, the capacity of the nanocrystalline titanium dioxide to remove U(VI) from water decreased in the presence of inorganic carbonate at pH > 6.0. Adsorption isotherms, Fourier transform infrared (FTIR) spectroscopy, and surface charge measurements were used to investigate the causes of the reduced capacity. The surface charge and the FTIR measurements suggested that the adsorbed U(VI) species was not complexed with carbonate at neutral pH values. The decreased capacity of titanium dioxide to remove U(VI) from water in the presence of carbonate at neutral to alkaline pH values was attributed to the aqueous complexation of U(VI) by inorganic carbonate. The nanocrystalline titanium dioxide had four times the capacity of commercially available titanium dixoide (Degussa P-25) to adsorb U(VI) from water at pH 6 and total inorganic carbonate concentration of 0.01 M. Consequently, the novel material was used to treat DU-contaminated water at a Department of Defense (DOD) site

Potassium iodate assisted synthesis of titanium dioxide nanoparticles with superior water-dispersibility.

Science.gov (United States)

Wang, Yawen; Duo, Fangfang; Peng, Shiqi; Jia, Falong; Fan, Caimei

2014-09-15

In this paper, we report a novel polyol process to synthesize highly water-dispersible anatase titanium dioxide (TiO2) nanoparticles (∼5 nm) by the introduction of inorganic oxidizing agent--KIO3. The obtained TiO2 nanoparticles are well dispersible in water at pH≥5.0 and the resulting aqueous dispersion remains stable over months. The superior water-dispersibility of as-formed TiO2 is ascribed to the electrostatic repulsion from carboxylic acid group modified on TiO2 nanoparticles, which is the oxidation product of solvent diethylene glycol (DEG) by KIO3. Based on the characterization results, the formation processes of water-dispersibility TiO2 nanoparticles are proposed. Meanwhile, the synthesized TiO2 nanoparticles are found to be doped by iodine and exhibit excellent photocatalytic activity on degradation of rhodamine-B (RhB) under visible-light irradiation. The further tests demonstrate that the O(2-) is the main active species during photodegradation of RhB. Copyright © 2014 Elsevier Inc. All rights reserved.

Studies of the surface of titanium dioxide. IV. The hydrogen-deuterium equilibration reaction

International Nuclear Information System (INIS)

Iwaki, T.; Katsuta, K.; Miura, M.

1981-01-01

The interaction of hydrogen with the surface of titanium dioxide has been studied in connection with the hydrogen-reduction mechanism of titanium dioxide, by means of such measurements as weight decrease, magnetic susceptibility, hydrogen uptake, and electrical conductance. It was postulated in the previous study that the rate-determining step of the hydrogen-reduction reaction may be the formation of surface hydroxyl groups, followed by the rapid removal of water molecules from the surface. In this study, the interactions between hydrogen and the surface of titanium dioxide were investigated by measuring the hydrogen-deuterium equilibration reaction, H 2 + D 2 = 2HD, at temperatures above 200 0 C on both surfaces before and after hydrogen reduction to compare the differences in the reactivities

Influence of Irradiance, Flow Rate, Reactor Geometry, and Photopromoter Concentration in Mineralization Kinetics of Methane in Air and in Aqueous Solutions by Photocatalytic Membranes Immobilizing Titanium Dioxide

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Ignazio Renato Bellobono

2008-01-01

Full Text Available Photomineralization of methane in air (10.0–1000 ppm (mass/volume of C at 100% relative humidity (dioxygen as oxygen donor was systematically studied at 318±3 K in an annular laboratory-scale reactor by photocatalytic membranes immobilizing titanium dioxide as a function of substrate concentration, absorbed power per unit length of membrane, reactor geometry, and concentration of a proprietary vanadium alkoxide as photopromoter. Kinetics of both substrate disappearance, to yield intermediates, and total organic carbon (TOC disappearance, to yield carbon dioxide, were followed. At a fixed value of irradiance (0.30 W⋅cm-1, the mineralization experiments in gaseous phase were repeated as a function of flow rate (4–400 m3⋅h−1. Moreover, at a standard flow rate of 300 m3⋅h−1, the ratio between the overall reaction volume and the length of the membrane was varied, substantially by varying the volume of reservoir, from and to which circulation of gaseous stream took place. Photomineralization of methane in aqueous solutions was also studied, in the same annular reactor and in the same conditions, but in a concentration range of 0.8–2.0 ppm of C, and by using stoichiometric hydrogen peroxide as an oxygen donor. A kinetic model was employed, from which, by a set of differential equations, four final optimised parameters, k1 and K1, k2 and K2, were calculated, which is able to fit the whole kinetic profile adequately. The influence of irradiance on k1 and k2, as well as of flow rate on K1 and K2, is rationalized. The influence of reactor geometry on k values is discussed in view of standardization procedures of photocatalytic experiments. Modeling of quantum yields, as a function of substrate concentration and irradiance, as well as of concentration of photopromoter, was carried out very satisfactorily. Kinetics of hydroxyl radicals reacting between themselves, leading to hydrogen peroxide, other than with substrate or

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

International Nuclear Information System (INIS)

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

2011-01-01

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-SiO 2 ) with diameter in range 200 nm, which are ideal supports for nanocrystalline titanium dioxide (TiO 2 ). The detailed microscopic and spectroscopic characterizations of core/shell structure (m-SiO 2 /TiO 2 ) 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 TiO 2 -Degussa P25 catalyst is detected.

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

Science.gov (United States)

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.

Green oxidations: Titanium dioxide induced tandem oxidation coupling reactions

OpenAIRE

Jeena, Vineet; Robinson, Ross S

2009-01-01

Summary The application of titanium dioxide as an oxidant in tandem oxidation type processes is described. Under microwave irradiation, quinoxalines have been synthesized in good yields from the corresponding ?-hydroxyketones.

Pharmaceutical/food grade titanium dioxide particles are absorbed into the bloodstream of human volunteers.

Science.gov (United States)

Pele, Laetitia C; Thoree, Vinay; Bruggraber, Sylvaine F A; Koller, Dagmar; Thompson, Richard P H; Lomer, Miranda C; Powell, Jonathan J

2015-09-02

Exposure to persistent engineered nano and micro particles via the oral route is well established. Animal studies have demonstrated that, once ingested, a small proportion of such particles translocate from the gastrointestinal tract to other tissues. Exposure to titanium dioxide is widespread via the oral route, but only one study has provided indirect evidence (total titanium analyses) of absorption into the blood stream in humans. We sought to replicate these observations and to provide additional evidence for particulate uptake. Human volunteers with normal intestinal permeability were orally administered 100 mg pharmaceutical/food grade titanium dioxide. Blood samples were collected from 0.5 to 10 h post ingestion and analysed for the presence of reflectant bodies (particles) by dark field microscopy, and for total titanium by inductively coupled plasma mass spectrometry (ICP-MS). Blood film analyses implied early absorption of particles (2 h) with a peak maximum at 6 h following ingestion. The presence of these reflectant particles in blood roughly mirrored the levels of total titanium by ICP-MS, providing good evidence for the latter being a measure of whole particle (titanium dioxide) absorption. This study shows that a fraction of pharmaceutical/food grade titanium dioxide is absorbed systemically by humans following ingestion. It confirms that at least two routes of particle uptake may exist in the human gut- one proximal and one distal. Further work should quantify human exposure and uptake of such persistent particles.

Titanium dioxide enrichment of sialic acid-containing glycopeptides

DEFF Research Database (Denmark)

Palmisano, Giuseppe; Lendal, Sara E; Larsen, Martin Røssel

2011-01-01

the glycosylation site of N-linked sialylated glycoproteins. The method relies on the specificity of titanium dioxide affinity chromatography to isolate sialic acid-containing glycopeptides. After enzymatic release of the glycans, the enriched sialylated glycopeptides are analyzed by mass spectrometry...

Fabrication and characterization of nanostructured anatase TiO{sub 2} films prepared by electrochemical anodization and their photocatalytic properties

Energy Technology Data Exchange (ETDEWEB)

Yurddaskal, Metin [Dokuz Eylul University, The Graduate School of Natural and Applied Sciences, Buca 35390, Izmir (Turkey); Dokuz Eylul University, Center for Fabrication and Applications of Electronic Materials (EMUM), Buca, 35390, Izmir (Turkey); Dikici, Tuncay, E-mail: tuncay.dikici@ikc.edu.tr [Dokuz Eylul University, The Graduate School of Natural and Applied Sciences, Buca 35390, Izmir (Turkey); Izmir Katip Celebi University, Department of Materials Science and Engineering, Cigli 35620, Izmir (Turkey); Yildirim, Serdar [Dokuz Eylul University, The Graduate School of Natural and Applied Sciences, Buca 35390, Izmir (Turkey); Dokuz Eylul University, Center for Fabrication and Applications of Electronic Materials (EMUM), Buca, 35390, Izmir (Turkey); Yurddaskal, Melis [Celal Bayar University, Department of Mechanical Engineering, Muradiye, 45140 Manisa (Turkey); Toparli, Mustafa; Celik, Erdal [Dokuz Eylul University, Center for Fabrication and Applications of Electronic Materials (EMUM), Buca, 35390, Izmir (Turkey); Dokuz Eylul University, Department of Metallurgical and Materials Engineering, Buca 35390, Izmir (Turkey)

2015-12-05

In this study, nanostructured anatase titanium dioxide (TiO{sub 2}) films were fabricated by electrochemical anodization of titanium first, and then annealed at 500 °C for 2 h. Effect of electrolyte concentration, anodization time and electrolyte temperature on the surface morphology of the resulting TiO{sub 2} thin films were investigated. The phase structures, surface morphology and chemical composition were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity tests of the samples were evaluated by the degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods of time. The results showed that the structure of nanostructured TiO{sub 2} films depended strongly on the anodization parameters. It was found that there were micro-scale pores (<10 μm) and nano-scale pores (diameter in the range from 40 to 70 nm) on the anodized titanium surfaces. This study indicated that structures, surface morphology, and surface area of the nanostructured anatase TiO{sub 2} films played an important role on their photocatalytic performance. The results clearly proved that nanostructured anatase TiO{sub 2} film prepared with optimum process parameters resulted in enhancement of the photocatalytic activity. - Highlights: • TiO{sub 2} thin films were prepared on titanium substrates by electrochemical anodization at 30 V. • Effect of various anodization parameters on the photocatalytic activity of titanium was investigated. • Micro- and nanoscale TiO{sub 2} pores formed on the titanium by anodizing. • Surface morphology of the TiO{sub 2} films plays an important role on the photocatalytic performance. • The sample anodized for 240 min showed the highest photocatalytic activity.

Performance of NiFe2O4-SiO2-TiO2 Magnetic Photocatalyst for the Effective Photocatalytic Reduction of Cr(VI in Aqueous Solutions

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Mike O. Ojemaye

2017-01-01

Full Text Available Investigation into the reduction of Cr(VI in aqueous solution was carried out through some batch photocatalytic studies. The photocatalysts used were silica coated nickel ferrite nanoparticles (NiFe2O4-SiO2, nickel ferrite titanium dioxide (NiFe2O4-TiO2, nickel ferrite silica titanium dioxide (NiFe2O4-SiO2-TiO2, and titanium dioxide (TiO2. The characterization of the materials prepared via stepwise synthesis using coprecipitation and sol-gel methods were carried out with the aid of X-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, Fourier transform infrared (FTIR spectroscopy, thermal gravimetric analysis (TGA, and vibrating sample magnetometry (VSM. The reduction efficiency was studied as a function of pH, photocatalyst dose, and contact time. The effects of silica interlayer between the magnetic photocatalyst materials reveal that reduction efficiency of NiFe2O4-SiO2-TiO2 towards Cr(VI was higher than that of NiFe2O4-TiO2. However, TiO2 was observed to have the highest reduction efficiency at all batch photocatalytic experiments. Kinetics study shows that photocatalytic reduction of Cr(VI obeyed Langmuir-Hinshelwood model and first-order rate kinetics. Regenerability study also suggested that the photocatalyst materials can be reused.

Interaction of titanium and vanadium with carbon dioxide in heating

International Nuclear Information System (INIS)

Vlasyuk, R.Z.; Kurovskii, V.Y.; Lyapunov, A.P.; Radomysel'skii, I.D.

1986-01-01

To obtain prediction data on the change in properties of titaniumand vanadium-base powder metallurgy materials operating in a carbon dioxide atmosphere, and also to clarify the mechanism of their interaction with the gas in this work, gravimetric investigations of specimens heated at temperatures of 300-1000 C and an x-ray diffraction analysis of their surface were made and the composition of the gas in the heating chamber was studied. The results of the investigations indicate a similarity between the mechanisms of interaction of titanium and vanadium with carbon dioxide including the formation of oxides on the surface of the metal with subsequent carbidization at temperatures above 800 C. On the basis of the data obtained, it may be concluded that the operating temperature limits of titanium- or vanadium-base materials in carbon dioxide must not exceed 400 and 600 C, respectively

Surface characterisation and electrochemical behaviour of porous titanium dioxide coated 316L stainless steel for orthopaedic applications

International Nuclear Information System (INIS)

Nagarajan, S.; Rajendran, N.

2009-01-01

Porous titanium dioxide was coated on surgical grade 316L stainless steel (SS) and its role on the corrosion protection and enhanced biocompatibility of the materials was studied. X-ray diffraction analysis (XRD), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were carried out to characterise the surface morphology and also to understand the structure of the as synthesised coating on the substrates. The corrosion behaviour of titanium dioxide coated samples in simulated body fluid was evaluated using polarisation and impedance spectroscopy studies. The results reveal that the titanium dioxide coated 316L SS exhibit a higher corrosion resistance than the uncoated 316L SS. The titanium dioxide coated surface is porous, uniform and also it acts as a barrier layer to metallic substrate and the porous titanium dioxide coating induces the formation of hydroxyapatite layer on the metal surface.

Titanium dioxide nanoparticles modified by salicylic acid and arginine: Structure, surface properties and photocatalytic decomposition of p-nitrophenol

Energy Technology Data Exchange (ETDEWEB)

Li, Lei [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China, Taiyuan 030051 (China); Feng, Yujie, E-mail: yujief@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Liu, Youzhi; Wei, Bing; Guo, Jiaxin; Jiao, Weizhou [Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China, Taiyuan 030051 (China); Zhang, Zhaohan [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Zhang, Qiaoling, E-mail: zhangqiaoling@nuc.edu.cn [Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China, Taiyuan 030051 (China)

2016-02-15

Graphical abstract: A simple and versatile synthetic method to produce TiO{sub 2} nanoparticles surface-modified with various organic capping agents can be used for novel multifunctional photocatalysts as required for various applications in energy saving and environmental protection. - Highlights: • SA and Arg was modified through the method of dipping treatment-based on chemical adsorption in saturated solution. • Surface modified TiO{sub 2} applied in photodecomposition of nitroaromatic. • The photoreduction of nitroaromatic and photocatalytic activity under visible light irradiation were enhanced by TiO{sub 2}–SA–Arg. • TiO{sub 2}–SA–Arg showed better lipophilic, dispersion and adsorption properties. - Abstract: In this study, titanium dioxide (TiO{sub 2}) nanoparticles were surface-modified with salicylic acid (SA) and arginine (Arg) using an environmentally friendly and convenient method, and the bonding structure, surface properties and degradation efficiency of p-nitrophenol (PNP) were investigated. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), water contact angle (WCA) measurements, ζ-potentiometric analysis, UV/visible diffuse reflectance spectroscopy (UV–vis DRS), and thermogravimetric analysis (TGA) were performed to evaluate the modification effect. The degradation rates were determined by high-performance liquid chromatography (HPLC). The results show that bidentate or bridging bonds are most likely formed between SA/Arg and TiO{sub 2} surface. Surface modification with SA, Arg, or both can improve the lipophilic properties and decrease the zeta potential, and also result in a red shift of the absorption wavelength. TiO{sub 2} nanoparticles modified by Arg or both SA and Arg show a large specific surface area and pore volume. Further, degradation

Sorption rate of uranyl ions by hyphan cellulose exchangers and by hydrated titanium dioxide

International Nuclear Information System (INIS)

Ambe, F.; Burba, P.; Lieser, K.H.

1979-01-01

Sorption of uranyl ions by the cellulose exchanger Hyphan proceeds rather fast. Two steps are observed with half-times of the order of 10 s and 2 min. The majority of the uranyl ions is bound in 1 min. Sorption of uranyl ions by titanium dioxide is a very slow process. For particle sizes between 0,1 and 0,5 mm the half-time is about 3 h and equilibrium is attained in about 1 day. The effect of stirring suspensions of inorganic sorbents like titanium dioxide in solution is investigated in detail. Sorption of uranyl ions by titanium dioxide and change in pH in solution are measured simultaneously as a function of time. (orig.) [de

High performance nano-titania photocatalytic paper composite. Part I: Experimental design study for TiO2 composite sheet using a natural zeolite microparticle system and its photocatalytic property

International Nuclear Information System (INIS)

Ko, Seonghyuk; Pekarovic, Jan; Fleming, Paul D.; Ari-Gur, Pnina

2010-01-01

Nanosized titanium dioxide (TiO 2 ) photocatalytic papers were successfully prepared using a natural zeolite microparticle retention aid in papermaking. Applying a factorial experimental design, natural zeolite has been demonstrated to be the most significant and interactive factor for increasing the TiO 2 retention rate in paper stock. The photocatalysis of as-prepared sheets was evaluated with toluene as one of the representative volatile organic compounds (VOCs). Under UV irradiation, it was shown to be effective in removing gaseous toluene by photodecomposition, assisted by adsorption. It was revealed that natural zeolite plays an important role in both increasing retention rate of TiO 2 nanoparticles and enhancing photocatalytic efficiency of the paper. The photocatalytic paper can be potentially applied for environmental purification.

Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Kartsonakis, I. A., E-mail: ikartsonakis@ims.demokritos.gr; Kontogiani, P.; Pappas, G. S.; Kordas, G. [NCSR ' DEMOKRITOS' , Sol-Gel Laboratory, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems (Greece)

2013-06-15

This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 {+-} 15 and 221 {+-} 10 nm, respectively, were synthesized using emulsion polymerization and the sol-gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue-black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

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

Science.gov (United States)

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

Titanium Dioxide Nanoparticles: a Risk for Human Health?

Science.gov (United States)

Grande, Fedora; Tucci, Paola

2016-01-01

Titanium dioxide (TiO2) is a natural oxide of the element titanium with low toxicity, and negligible biological effects. The classification as bio-inert material has given the possibility to normal-sized (>100 nm) titanium dioxide particles (TiO2-NPs) to be extensively used in food products and as ingredients in a wide range of pharmaceutical products and cosmetics, such as sunscreens and toothpastes. Therefore, human exposure may occur through ingestion and dermal penetration, or through inhalation route, during both the manufacturing process and use. In spite of the extensively use of TiO2-NPs, the biological effects and the cellular response mechanisms are still not completely elucidated and thus a deep understanding of the toxicological profile of this compound is required. The main mechanism underlining the toxicity potentially triggered by TiO2-NPs seems to involve the reactive oxygen species (ROS) production, resulting in oxidative stress, inflammation, genotoxicity, metabolic change and potentially carcinogenesis. The extent and type of cell damage strongly depend on chemical and physical characteristics of TiO2-NPs, including size, crystal structure and photo-activation. In this mini-review, we would like to discuss the latest findings on the adverse effects and on potential human health risks induced by TiO2-NPs exposure.

Nanoparticulate cerium dioxide and cerium dioxide-titanium dioxide composite thin films on glass by aerosol assisted chemical vapour deposition

International Nuclear Information System (INIS)

Qureshi, Uzma; Dunnill, Charles W.; Parkin, Ivan P.

2009-01-01

Two series of composite thin films were deposited on glass by aerosol assisted chemical vapour deposition (AACVD)-nanoparticulate cerium dioxide and nanoparticulate cerium dioxide embedded in a titanium dioxide matrix. The films were analysed by a range of techniques including UV-visible absorption spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive analysis by X-rays. The AACVD prepared films showed the functional properties of photocatalysis and super-hydrophilicity. The CeO 2 nanoparticle thin films displaying photocatalysis and photo-induced hydrophilicity almost comparable to that of anatase titania.

Synthesis and photocatalytic activity of mesoporous nanocrystalline Fe-doped titanium dioxide

KAUST Repository

Qamar, Mohd

2014-07-01

Synthesis of mesoporous nanocrystalline iron-doped titania following the sol-gel method is presented in this work. Samples with various molar ratios (0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10 and 20%) of Fe to Ti were prepared. The particle size was found to be in the range of ∼12 nm while mesopores were approximately near to ∼5.5 nm. The effect of Fe as doping element on titania properties, such as crystallite size, surface area, pore size, pore volume and d-spacing was investigated. Moreover, distribution of Fe in TiO2 matrix was determined by elemental mapping whereas change in absorption properties was evaluated by diffuse reflectance spectroscopy. It was observed that as the Fe content was increased, a partial phase transformation from anatase to rutile and pseudorutile took place. Effect of ultraviolet, ultraviolet-visible and visible radiations on the photocatalytic activity of these catalysts was studied by removal of Methyl Orange as model pollutant. As results, it was found that the photocatalytic activity of such catalysts depends strongly on Fe amount and type of radiation. © 2013 Elsevier B.V.

Preparation of TiO{sub 2} nanotubes, study of their morphology and photocatalytic properties; Priprava nanotrubiek TiO{sub 2}, studium ich morfologie a fotokatalytickych vlastnosti

Energy Technology Data Exchange (ETDEWEB)

Motola, M.; Plasch, G. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra anorganickej chemie, 84215 Bratislava (Slovakia); Satrapinskyy, L. [Univerzita Komenskeho, Fakulta matematiky, fyziky a informatiky, Katedra experimentalnej fyziky, 84248 Bratislava (Slovakia)

2013-04-16

The present paper deals with the synthesis and characterization of titanium dioxide nanotubes (TNTs) for photocatalytic applications. Nanotubes were prepared by electrochemical anodic oxidation. The samples were heat treated by annealing to become photocatalytically active. Using scanning electron microscopy morphology of the nanotubes was studied. Phase composition of samples was measured by X-ray diffraction (XRD). The photocatalytic activity of nanotubes leads to decrease of the concentration of Rhodamine B during irradiation with UV A light. The photocatalytic activity of nanotubes was compared with the photocatalytic activity of Aeroxide P25 nanocrystalline titania powder. The best photocatalytic active show the samples annealed at 400 grad C. (authors)

An LED Approach for Measuring the Photocatalytic Breakdown of Crystal Violet Dye

Science.gov (United States)

Ryan, Robert E.; Underwood, Lauren W.; ONeal, Duane; Pagnutti, Mary; Davis, Bruce A.

2009-01-01

A simple technique to assess the reactivity of photocatalytic coatings sprayed onto transmissive glass surfaces was developed. This new method uses ultraviolet (UV) gallium nitride (GaN) light-emitting diodes (LEDs) to drive a photocatalytic reaction (the photocatalytic breakdown of a UV-resistant dye applied to a surface coated with the semiconductor titanium dioxide); and then a combination of a stabilized white light LED and a spectrometer to track the dye degradation as a function of time. Simple, standardized evaluation techniques that assess photocatalytic materials over a variety of environmental conditions, including illumination level, are not generally available and are greatly needed prior to in situ application of photocatalytic technologies. To date, much research pertaining to this aspect of photocatalysis has been limited and has focused primarily on laboratory experiments using mercury lamps. Mercury lamp illumination levels are difficult to control over large ranges and are temporally modulated by line power, limiting their use in helping to understand and predict how photocatalytic materials will behave in natural environmental settings and conditions. The methodology described here, using steady-state LEDs and time series spectroradiometric techniques, is a novel approach to explore the effect of UV light on the photocatalytic degradation of a UV resistant dye (crystal violet). GaN UV LED arrays, centered around 365 nm with an adjustable DC power supply, are used to create a small, spatially uniform light field where the steady state light level can be varied over three to four orders of magnitude. For this study, a set of glass microscope slides was custom coated with a thinly sprayed layer of photocatalytic titanium dioxide. Crystal violet was then applied to these titanium-dioxide coated slides and to uncoated control slides. The slides were then illuminated at various light levels from the dye side of the slide by the UV LED array. To monitor

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

Science.gov (United States)

Hewitt, Rachel E; Vis, Bradley; Pele, Laetitia C; Faria, Nuno; Powell, Jonathan J

2017-10-01

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 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

Photocatalytic activity of titanium dioxide modified by Fe{sub 2}O{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wodka, Dawid [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland); Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4 (Switzerland); Socha, Robert P.; Bielańska, Elżbieta [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland); Elżbieciak-Wodka, Magdalena [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland); Department of Analytical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4 (Switzerland); Nowak, Paweł, E-mail: ncnowak@cyf-kr.edu.pl [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland); Warszyński, Piotr [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland)

2014-11-15

Highlights: • 1% Fe{sub 2}O{sub 3}/TiO{sub 2} composite showing high activity in the photocatalytic oxidation of organics was synthetized. • Electrochemical analysis indicated that surface modification of Degussa P25 by Fe{sub 2}O{sub 3} causes the appearance of surface states in such a material. • The enhanced activity of the prepared composite may be ascribed to the occurrence of the photo-Fenton process. - Abstract: Photocatalytic activity of Fe{sub 2}O{sub 3}/TiO{sub 2} composites obtained by precipitation was investigated. The composite material containing 1.0 wt% of iron(III) oxide nanoparticles was obtained by depositing Fe{sub 2}O{sub 3} on the Evonic-Degussa P25 titania surface. SEM, XPS, DRS, CV and EIS techniques were applied to examine synthetized pale orange photocatalyst. The XPS measurements revealed that iron is present mainly in the +3 oxidation state but iron in the +2 oxidation state can be also detected. Electrochemical analysis indicated that surface modification of Degussa P25 by Fe{sub 2}O{sub 3} causes the appearance of surface states in such a material. Nevertheless, based on the DRS measurement it was shown that iron(III) oxide nanoparticles modified the P25 spectral properties but they did not change the band gap width. The photocatalytic activity of Fe{sub 2}O{sub 3}/TiO{sub 2} composite was compared to photocatalytic activity of pristine P25 in photooxidation reaction of model compounds: oxalic acid (OxA) and formic acid (FA). Photodecomposition reaction was investigated in a batch reactor containing aqueous suspension of a photocatalyst illuminated by either UV or artificial sunlight (halogen lamp). The tests proved that nanoparticles deposited on titania surface triggers the increase in photocatalytic activity, this increase depends however on the decomposed substance.

Mineralization of bacterial cell mass on a photocatalytic surface in air

International Nuclear Information System (INIS)

Jacoby, W.A.; Maness, P.C.; Wolfrum, E.J.; Blake, D.M.; Fennell, J.A.

1998-01-01

Whole cells deposited on a titanium dioxide-coated surface have been oxidized in air to carbon dioxide via photocatalysis. This paper provides the first evidence that the organic matter in whole cells can be completely oxidized. Three experimental techniques were employed to monitor this reaction: scanning electron microscopy, 14 C radioisotope labeling experiments establish that the carbon content of E. coli is oxidized to form carbon dioxide with substantial closure of the mass balance. The batch reactor experiments corroborate the mass balance and provide a preliminary indication of the rate of the oxidation reaction. These results provide evidence that a photocatalytic surface used for disinfection can also be self-cleaning in an air-solid system

Silver Modified Degussa P25 for the Photocatalytic Removal of Nitric Oxide

Directory of Open Access Journals (Sweden)

Neil Bowering

2007-01-01

Full Text Available A study of the photocatalytic behaviour of silver modified titanium dioxide materials for the decomposition and reduction of nitric oxide (NO gas has been carried out. The effects of silver loading, calcination temperature, and reaction conditions have been investigated. Prepared photocatalysts were characterised using XRD, TEM, and XPS. A continuous flow reactor was used to determine the photocatalytic activity and selectivity of NO decomposition in the absence of oxygen as well as NO reduction using CO as the reducing agent, over the prepared photocatalysts. XRD and TEM analysis of the photocatalysts showed that crystalline silver nitrate particles were present on the titanium dioxide surface after calcination at temperatures of up to 200∘C. The silver nitrate particles are thermally decomposed to form metallic silver clusters at higher temperatures. XPS analysis of the photocatalysts showed that for each of the temperatures used, both Ag+ and Ag0 were present and that the Ag0/Ag+ ratio increased with increasing calcination temperature. The presence of metallic silver species on the TiO2 surface dramatically increased the selectivity for N2 formation of both decomposition and reduction reactions. When CO was present in the reaction gas, selectivities of over 90% were observed for all the Ag-TiO2 photocatalysts that had been calcined at temperatures above 200∘C. Unfortunately these high selectivities were at the expense of photocatalytic activity, with lower NO conversion rates than those achieved over unmodified TiO2 photocatalysts.

Enhanced photocatalytic properties of hierarchical three-dimensional TiO{sub 2} grown on femtosecond laser structured titanium substrate

Energy Technology Data Exchange (ETDEWEB)

Huang, Ting, E-mail: huangting@bjut.edu.cn; Lu, Jinlong; Xiao, Rongshi; Wu, Qiang; Yang, Wuxiong

2017-05-01

Highlights: • The hierarchical 3D-TiO{sub 2} is fabricated on femtosecond laser structured Ti substrate. • The formation mechanism of hierarchical 3D-TiO{sub 2} is proposed. • The structure-induced improvement of photocatalytic activity is reported. - Abstract: Three-dimensional micro-/nanostructured TiO{sub 2} (3D-TiO{sub 2}) fabricated on titanium substrate effectively improves its performance in photocatalysis, dye-sensitized solar cell and lithium-ion battery applications. In this study, the hierarchical 3D-TiO{sub 2} with anatase phase directly grown on femtosecond laser structured titanium substrate is reported. First, the primary columnar arrays were fabricated on the surface of titanium substrate by femtosecond laser structuring. Next, the secondary nano-sheet substructures were grown on the primary columnar arrays by NaOH hydrothermal treatment. Followed by ion-exchange process in HCl and annealing in the air, the hierarchical anatase 3D-TiO{sub 2} was achieved. The hierarchical anatase 3D-TiO{sub 2} exhibited enhanced performances in light harvesting and absorption ability compared to that of nano-sheet TiO{sub 2} grown on flat titanium surface without femtosecond laser structuring. The photocatalytic degradation of methyl orange reveals that photocatalytic efficiency of the hierarchical anatase 3D-TiO{sub 2} was improved by a maximum of 57% compared to that of nano-sheet TiO{sub 2} (55% vs 35%). Meanwhile, the hierarchical anatase 3D-TiO{sub 2} remained mechanically stable and constant in consecutive degradation cycles, which promises significance in practical application.

Titania nanotube arrays surface-modified with ZnO for enhanced photocatalytic applications

Energy Technology Data Exchange (ETDEWEB)

Nageri, Manoj; Kalarivalappil, Vijila; Vijayan, Baiju K.; Kumar, Viswanathan, E-mail: vkumar10@yahoo.co.in

2016-05-15

Highlights: • Heterostructures of TNA/ZnO synthesised through potentiostatic anodisation followed by hydrothermal method. • Evaluation of morphological features of the heterostructure with hydrothermal processing time. • Correlation of photocatalytic activity of the hetrostructure with its morphology and surface texture. - Abstract: Well ordered titanium dioxide nanotube arrays (TNA) of average diameter 129 nm and wall thickness of 25 nm were fabricated through potentiostatic anodisation of titanium (Ti) metal substrates. Such TNA were subsequently surface-modified with various amounts of zinc oxide (ZnO) nanopowders using hydrothermal technique to obtain heterogeneous TNA/ZnO nanostructures. The crystalline phase and surface microstructure of the heterostructures were determined by X-ray diffraction, Raman spectroscopy and scanning electron microscopy respectively. The morphology of the heterostructures strongly depended on the hydrothermal conditions employed. The photocatalytic activity of the heterostructures have also been investigated and correlated with their surface morphology and texture.

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

Science.gov (United States)

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

Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

International Nuclear Information System (INIS)

Kartsonakis, I. A.; Kontogiani, P.; Pappas, G. S.; Kordas, G.

2013-01-01

This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 ± 15 and 221 ± 10 nm, respectively, were synthesized using emulsion polymerization and the sol–gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue–black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

Behavior of the new composites obtained from fly ash and titanium dioxide in removing of the pollutants from wastewater

Energy Technology Data Exchange (ETDEWEB)

Visa, Maria; Andronic, Luminita; Enesca, Alexandru

2016-12-01

Graphical abstract: - Highlights: • A novel substrates FLY1, 2, 3 and FLY2NPt is obtained by hydrothermal synthesis. • The composite type structure has specific surface ten times higher than fly ash. • Simultaneous removal of three pollutants reaches efficiencies above 80%. • Kinetic investigations show fast adsorption of the dye on the new composite. - Abstract: The goal of this paper was to develop a low-temperature TiO{sub 2}-fly ash (TiO{sub 2}-FA) composite based on interaction in alkaline solution using hydrothermal methods, to obtain crystalline nanocomposite at low temperature. These composites are interesting to be applied in visible photocatalysis/adsorption simultaneous advanced wastewater processes. Combining fly ash with titanium dioxide has the following advantages: (1) the titanium oxide crystallites grow on the support (active fly ash); (2) pollutant molecules migrate to the surface of TiO{sub 2} can be degraded by photocatalysis; and (3) activated fly ash substrates are regenerated in situ. The composites were characterized by the scanning electron microscopy (SEM) and atomic force microscopy (AFM) for morphological characterization of the surface, X-ray diffraction (XRD) for phase and crystallinity analysis, UV–vis spectroscopy to calculate the energy band gap, surface analysis by determining the contact angle, porosity analysis (BET). The photocatalytic property of the composites was evaluated by dye (methylene blue), surfactant (dodecylbenzenesulfonate–SDBS) degradation under UV and Visible irradiation. The adsorption tests were made on heavy metal (Cu{sup 2+}) cation. Properties of composites were correlated with the adsorption/photocatalytic activity of the samples.

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

Energy Technology Data Exchange (ETDEWEB)

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 574 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.

Experimental study of photocatalytic concrete products for air purification

Energy Technology Data Exchange (ETDEWEB)

Huesken, G.; Hunger, M.; Brouwers, H.J.H. [Department of Civil Engineering, Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

2009-12-15

Air quality in inner-city areas is a topic which receives much attention nowadays but in the coming years, the overall interest on this topic will become even bigger. One major concern is caused by the reduction of the limiting values given by the European Council Directive 1999/30/EC [Relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air. Official Journal of the European Communities 1999, L 163/41-60] and increasing traffic rates especially for diesel powered passenger cars and freight vehicles. A promising approach for solving the problem of nitrogen oxides (NO{sub x}) is the photochemical conversion of nitrogen oxides to low concentrated nitrates due to heterogeneous photocatalytic oxidation (PCO) using titanium dioxide (TiO{sub 2}) as photocatalyst. A variety of products containing TiO{sub 2} are already available on the European market and their working mechanism under laboratory conditions is proven. However, there is still a lack of transforming the experimental results obtained under laboratory conditions to practical applications considering real world conditions. This paper presents the research conducted on photocatalytic concrete products with respect to the evaluation of air-purifying properties. The degradation process of nitric oxide (NO) under laboratory conditions is studied using a test setup for measuring the performance of photocatalytic active concrete products. The test setup uses the UV-A induced degradation of NO and is oriented on the ISO standard ISO 22197-1:2007. Besides the introduction of the test setup, a uniform measuring procedure is presented to the reader which allows for an evaluation and direct comparison of the performance of photocatalytic active concrete products. This kind of direct comparison was not possible so far. Furthermore, the results of a comparative study on varying photocatalytic concrete products of the European market will be discussed

Sensitivity of bacteria to photoactivated titanium dioxide in comparison with UV irradiation

International Nuclear Information System (INIS)

Kersters, Ilse; De Keyser, Tilly; Verstraete, Willy

1998-01-01

Titanium dioxide was used as a photocatalyst to generate hydroxyl radicals in a flowthrough water reactor. Experiments were performed with cultures of Aeromonas hydrophila AWWX1 and Pseudomonas fluorescens R 2 f to evaluate the disinfection capabilities of the reactor. Although a decrease in viable counts was observed with long-wavelength (λ=370 nm) irradiated TiO 2 pellets, direct UV 254 irradiation seems a superior technology for the disinfection of transparent potable water since the viable counts of the test strains declined stronger (2-5 logs) and faster (20x) in UV 254 -treated water than in photoactivated TiO 2 -treated water. Outdoor tests conducted in the summer noonday sun showed that the viable counts of Aeromonas hydrophila AWWX1 decreased strongly (ca 5 log units) in transparent and turbid water samples (750 NTU) exposed to natural sunlight (47,000 lux). The addition of TiO 2 to the solar irradiated waters did not influence the die-off of the strain. These observations indicate that the photocatalytic approach does not offer real prospects as an alternative technology for the disinfection of drinking water. (author)

Analysis of X-ray diffraction of the titanium dioxide (TiO_2) synthesized by the Pechini Method for application in heterogeneous photocatalysis processes

International Nuclear Information System (INIS)

Oliveira, P.L.; Araujo, D.S.; Costa, A.C.F.M.; Oliveira, L.S.C.

2016-01-01

Titanium dioxide (TiO_2) is a polymorph commonly applied to heterogeneous photocatalysis processes for being relatively inexpensive and photo - stable. It is usually found in three different crystalline phases (anatase, rutile and brookite), which directly interfere in their photocatalytic efficiency. Therefore, this study aimed to investigate the obtainment of TiO_2 by Pechini method in different conditions for application in the heterogeneous photocatalysis process. For this purpose, it was evaluated by analysis of X-ray diffraction (XRD ) the behavior of TiO_2 materials synthesized in proportions of 2:1 and 3:1 (titanium isopropoxide/citric acid), pyrolyzed at 300°C/3h and 400°C /h and calcined at 400°C and 500°C/1h. The results revealed that the TiO_2 samples produced in the ratio of 2:1 and 3:1 isopropoxide/citric acid and calcined at 500°C/h presented the best results. (author)

Applied studies in solar photocatalytic detoxification: an overview

Energy Technology Data Exchange (ETDEWEB)

Malato, S.; Blanco, J.; Vidal, A.; Alarcon, D.; Maldonado, M.I.; Caceres, J.; Gernjak, W. [CIEMAT - Plataforma Solar de Almeria, Tabernas (Spain)

2003-10-01

The technical feasibility and performance of photocatalytic degradation of four water-soluble pesticides (diuron, imidacloprid, formetanate and methomyl) have been studied at pilot scale in two well-defined systems which are of special interest because natural-solar UV light can be used for them: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. The pilot plant is made up of compound parabolic collectors specially designed for solar photocatalytic applications. The initial concentration tested with imidacloprid, formetanate and methomyl was 50 and 30 mg/l with diuron, and the catalyst concentrations were 200 mg/l and 0.05 mM with TiO{sub 2} and iron, respectively. Total disappearance of the parent compounds, 90% mineralisation and toxicity reduction below the threshold (EC{sub 50}) have been attained with all pesticides tested. All these results have contributed to an evaluation of photocatalytic treatment capacity and comments on the main parameters of TiO{sub 2} and Fe separation from the treated water. (author)

Photocatalytic activity of sonochemically prepared TiO_2 decorated with silver nanoparticles

International Nuclear Information System (INIS)

Michal, R.

2017-01-01

A novel way of titanium dioxide synthesis using non-water environment was investigated. In synthesis, water causes aggregation of particles of titania thus reducing active surface significantly. To avoid this, a non- water environment such as toluene was employed. Reaction between solid precursor and gaseous ammonia was conducted in this environment using dried reactants in tempered glass reactor and irradiated by ultrasonic horn. As prepared powders were then calcinated and decorated with Ag nanoparticles. Photocatalytic activity was determined by TOC method and compared to P25 standard TiO_2. Samples were analysed by XRD and Raman spectroscopy and surface morphology was investigated by SEM. Powders prepared by this method had comparable or higher photocatalytic activity than P25. Ag nanoparticles seem to have no significant impact on photocatalytic activity whatsoever. (authors)

Biosensor-based real-time monitoring of paracetamol photocatalytic degradation.

Science.gov (United States)

Calas-Blanchard, Carole; Istamboulié, Georges; Bontoux, Margot; Plantard, Gaël; Goetz, Vincent; Noguer, Thierry

2015-07-01

This paper presents for the first time the integration of a biosensor for the on-line, real-time monitoring of a photocatalytic degradation process. Paracetamol was used as a model molecule due to its wide use and occurrence in environmental waters. The biosensor was developed based on tyrosinase immobilization in a polyvinylalcohol photocrosslinkable polymer. It was inserted in a computer-controlled flow system installed besides a photocatalytic reactor including titanium dioxide (TiO2) as photocatalyst. It was shown that the biosensor was able to accurately monitor the paracetamol degradation with time. Compared with conventional HPLC analysis, the described device provides a real-time information on the reaction advancement, allowing a better control of the photodegradation process. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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...

Human in vivo and in vitro studies on gastrointestinal absorption of titanium dioxide nanoparticles.

Science.gov (United States)

Jones, Kate; Morton, Jackie; Smith, Ian; Jurkschat, Kerstin; Harding, Anne-Helen; Evans, Gareth

2015-03-04

The study was designed to conduct human in vivo and in vitro studies on the gastrointestinal absorption of nanoparticles, using titanium dioxide as a model compound, and to compare nanoparticle behaviour with that of larger particles. A supplier's characterisation data may not fully describe a particle formulation. Most particles tested agreed with their supplied characterisation when assessed by particle number but significant proportions of 'nanoparticle formulations' were particles >100nm when assessed by particle weight. Oral doses are measured by weight and it is therefore important that the weight characterisation is taken into consideration. The human volunteer studies demonstrated that very little titanium dioxide is absorbed gastrointestinally after an oral challenge. There was no demonstrable difference in absorption for any of the three particle sizes tested. All tested formulations were shown to agglomerate in simulated gastric fluid, particularly in the smaller particle formulations. Further agglomeration was observed when dispersing formulations in polymeric or elemental foods. Virtually no translocation of titanium dioxide particles across the cell layer was demonstrated. This study found no evidence that nanoparticulate titanium dioxide is more likely to be absorbed in the gut than micron-sized particles. Crown Copyright © 2015. Published by Elsevier Ireland Ltd. All rights reserved.

Titanium dioxide nanoparticles: occupational exposure assessment in the photocatalytic paving production

International Nuclear Information System (INIS)

Spinazzè, Andrea; Cattaneo, Andrea; Limonta, Marina; Bollati, Valentina; Bertazzi, Pier Alberto; Cavallo, Domenico M.

2016-01-01

Limited data are available regarding occupational exposure assessment to nano-sized titanium dioxide (nano-TiO_2). The objective of this study is to assess the occupational exposure of workers engaged in the application of nano-TiO_2 onto concrete building materials, by means of a multi-metric approach (mean diameter, number, mass and surface area concentrations). The measurement design consists of the combined use of (i) direct-reading instruments to evaluate the total particle number concentrations relative to the background concentration and the mean size-dependent characteristics of particles (mean diameter and surface area concentration) and to estimate the 8-h time-weighted average (8-h TWA) exposure to nano-TiO_2 for workers involved in different working tasks; and (ii) filter-based air sampling, used for the determination of size-resolved particle mass concentrations. A further estimation was performed to obtain the mean 8-h TWA exposure values expressed as mass concentrations (µg nano-TiO_2/m"3). The multi-metric characterization of occupational exposure to nano-TiO_2 was significantly different both for different work environments and for each work task. Generally, workers were exposed to engineered nanoparticles (ENPs; <100 nm) mean levels lower than the recommended reference values and proposed occupational exposure limits (40,000 particle/cm"3; 300 µg/m"3) and relevant exposures to peak concentration were not likely to be expected. The estimated 8-h TWA exposure showed differences between the unexposed and exposed subjects. For these last, further differences were defined between operators involved in different work tasks. This study provides information on nano-TiO_2 number and mass concentration, size distribution, particles diameter and surface area concentrations, which were used to obtain work shift-averaged exposures.

Titanium dioxide nanoparticles: occupational exposure assessment in the photocatalytic paving production

Energy Technology Data Exchange (ETDEWEB)

Spinazzè, Andrea, E-mail: andrea.spinazze@uninsubria.it; Cattaneo, Andrea; Limonta, Marina [Università degli studi dell’Insubria, Dipartimento di Scienza e Alta Tecnologia (Italy); Bollati, Valentina; Bertazzi, Pier Alberto [Università degli Studi di Milano, EPIGET-Epidemiology, Epigenetics and Toxicology Lab, Dipartimento di Scienze Cliniche e di Comunità (Italy); Cavallo, Domenico M. [Università degli studi dell’Insubria, Dipartimento di Scienza e Alta Tecnologia (Italy)

2016-06-15

Limited data are available regarding occupational exposure assessment to nano-sized titanium dioxide (nano-TiO{sub 2}). The objective of this study is to assess the occupational exposure of workers engaged in the application of nano-TiO{sub 2} onto concrete building materials, by means of a multi-metric approach (mean diameter, number, mass and surface area concentrations). The measurement design consists of the combined use of (i) direct-reading instruments to evaluate the total particle number concentrations relative to the background concentration and the mean size-dependent characteristics of particles (mean diameter and surface area concentration) and to estimate the 8-h time-weighted average (8-h TWA) exposure to nano-TiO{sub 2} for workers involved in different working tasks; and (ii) filter-based air sampling, used for the determination of size-resolved particle mass concentrations. A further estimation was performed to obtain the mean 8-h TWA exposure values expressed as mass concentrations (µg nano-TiO{sub 2}/m{sup 3}). The multi-metric characterization of occupational exposure to nano-TiO{sub 2} was significantly different both for different work environments and for each work task. Generally, workers were exposed to engineered nanoparticles (ENPs; <100 nm) mean levels lower than the recommended reference values and proposed occupational exposure limits (40,000 particle/cm{sup 3}; 300 µg/m{sup 3}) and relevant exposures to peak concentration were not likely to be expected. The estimated 8-h TWA exposure showed differences between the unexposed and exposed subjects. For these last, further differences were defined between operators involved in different work tasks. This study provides information on nano-TiO{sub 2} number and mass concentration, size distribution, particles diameter and surface area concentrations, which were used to obtain work shift-averaged exposures.

Clinical and histomorphometrical study on titanium dioxide-coated external fixation pins.

Science.gov (United States)

Koseki, Hironobu; Asahara, Tomohiko; Shida, Takayuki; Yoda, Itaru; Horiuchi, Hidehiko; Baba, Koumei; Osaki, Makoto

2013-01-01

Pin site infection is the most common and significant complication of external fixation. In this work, the efficacy of pins coated with titanium dioxide (TiO(2)) for inhibition of infection was compared with that of stainless steel control pins in an in vivo study. Pins contaminated with an identifiable Staphylococcus aureus strain were inserted into femoral bone in a rat model and exposed to ultraviolet A light for 30 minutes. On day 14, the animals were sacrificed and the bone and soft tissue around the pin were retrieved. The clinical findings and histological findings were evaluated in 60 samples. Clinical signs of infection were present in 76.7% of untreated pins, but in only 36.7% of TiO(2)-coated pins. The histological bone infection score and planimetric rate of occupation for bacterial colonies and neutrophils in the TiO(2)-coated pin group were lower than those in the control group. The bone-implant contact ratio of the TiO(2)-coated pin group was significantly higher (71.4%) than in the control pin group (58.2%). The TiO(2) was successful in decreasing infection both clinically and histomorphometrically. The photocatalytic bactericidal effect of TiO(2) is thought to be useful for inhibiting pin site infection after external fixation.

X-ray photoelectron spectroscopy characterization of composite TiO{sub 2}-poly(vinylidenefluoride) films synthesised for applications in pesticide photocatalytic degradation

Energy Technology Data Exchange (ETDEWEB)

Losito, I.; Amorisco, A.; Palmisano, F.; Zambonin, P.G

2005-02-15

X-ray photoelectron spectroscopy (XPS) was adopted for the analytical characterization of composite titanium dioxide-poly(vinylidenefluoride) (TiO{sub 2}-PVDF) films developed for applications in the photocatalytic degradation of pollutants. The composites were deposited on glass substrates by casting or spin coating from TiO{sub 2}-PVDF suspensions in dimethylformamide (DMF). XPS data on the TiO{sub 2}-PVDF surface composition were used to optimize preparation conditions (composition of the TiO{sub 2}/PVDF suspension, deposition technique) in terms of titanium dioxide surface amount and film stability. The use of spin-coating deposition and the increase of TiO{sub 2} amount in the DMF suspensions were found to improve the titanium surface content, although high TiO{sub 2}/PVDF ratios led to film instability. PVDF-TiO{sub 2} films were also used in preliminary photocatalytic degradation tests on isoproturon, a phenylurea herbicide, under solar UV irradiation; the results were compared to direct photolysis to evaluate the catalytic efficiency of immobilized TiO{sub 2} and the role played by the PVDF film during the degradation process.

Solar photocatalytic cleaning of polluted water

International Nuclear Information System (INIS)

Bockelmann, D.

1994-01-01

Alternatively to biological, physical and chemical methods of waste water cleaning, photocatalysis can be employed. In this residue-free method, titanium dioxide particles are brought into contact with polluted water as photocatalysts. Under UV irradiation at wave-lengths below 400 nm, change carriers are generated in the semiconductor particles that act so intensely oxidizing as to completely degrade almost all organic pollutants in waste water. In this process, the ultra-violet part of the solar spectrum can be harnessed to generate oxidation equivalents. Thus, solar photocatalytic waste water cleaning is excellently suited for developing countries. (BWI) [de

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

DEFF Research Database (Denmark)

Raie, Diana S; Mhatre, Eisha; El-Desouki, Doaa S

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...

Selective recovery of titanium dioxide from low grade sources

CSIR Research Space (South Africa)

Van Vuuren, DS

2006-09-01

Full Text Available that is too fine for use in the chloride process  Perovskite (CaTiO3) resources in Colorado3. The main problem with utilizing a low-grade resource is the amount of chemical wastes produced per unit of pigment of produced. If a TiO2 bearing feedstock... The mineralogical form of the titanium oxide species affects the thermodynamic equilibrium of the reaction. Calcium titanate, CaTiO3 (Perovskite) is more stable than magnesium titanate MgTiO3, (Geikilite) which is more stable than titanium dioxide or ilmenite (Fe...

Solar photocatalytic mineralization of isoproturon over TiO{sub 2}/HY composite systems

Energy Technology Data Exchange (ETDEWEB)

Sharma, Mangalampalli V. Phanikrishna; Lalitha, Kannekanti; Durgakumari, Valluri; Subrahmanyam, Machiraju [Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad 500007 (India)

2008-03-15

The present investigation covers immobilization of titanium dioxide over HY support for the treatment of isoproturon pesticide. Catalysts are characterized by XRD, SEM-EDAX, TEM, BET surface area and UV-vis DRS. A detailed photocatalytic degradation study under solar light in aqueous suspensions with parameters like loading of TiO{sub 2} over HY, amount of the catalyst, concentration of substrate, pH effect, durability of the catalyst and comparison between suspended TiO{sub 2} and supported systems are reported. Mineralization of isoproturon is monitored by total organic carbon, chemical oxygen demand and a plausible mechanism is proposed for photocatalytic degradation based on degradation products. (author)

Nano-scale analysis of titanium dioxide fingerprint-development powders

International Nuclear Information System (INIS)

Reynolds, A J; Jones, B J; Sears, V; Bowman, V

2008-01-01

Titanium dioxide based powders are regularly used in the development of latent fingerprints on dark surfaces. For analysis of prints on adhesive tapes, the titanium dioxide is suspended in a surfactant and used in the form of a small particle reagent (SPR). Analysis of commercially available products shows varying levels of effectiveness of print development, with some powders adhering to the background as well as the print. Scanning electron microscopy (SEM) images of prints developed with different powders show a range of levels of aggregation of particles. Analytical transmission electron microscopy (TEM) of the fingerprint powder shows TiO 2 particles with a surrounding coating, tens of nanometres thick, consisting of Al and Si rich material. X ray photoelectron spectroscopy (XPS) is used to determine the composition and chemical state of the surface of the powders; with a penetration depth of approximately 10nm, this technique demonstrates differing Ti: Al: Si ratios and oxidation states between the surfaces of different powders. Levels of titanium detected with this technique demonstrate variation in the integrity of the surface coating. The thickness, integrity and composition of the Al/Si-based coating is related to the level of aggregation of TiO 2 particles and efficacy of print development.

Nano-scale analysis of titanium dioxide fingerprint-development powders

Energy Technology Data Exchange (ETDEWEB)

Reynolds, A J; Jones, B J [Experimental Techniques Centre, Brunei University, Kingston Lane, Uxbridge, Middlesex, UB8 3PH (United Kingdom); Sears, V; Bowman, V [Fingerprint and Footwear Forensics, Home Office Scientific Development Branch, Sandridge, St Albans, Hertfordshire, AL4 9HQ (United Kingdom)], E-mail: b.j.jones@physics.org

2008-08-15

Titanium dioxide based powders are regularly used in the development of latent fingerprints on dark surfaces. For analysis of prints on adhesive tapes, the titanium dioxide is suspended in a surfactant and used in the form of a small particle reagent (SPR). Analysis of commercially available products shows varying levels of effectiveness of print development, with some powders adhering to the background as well as the print. Scanning electron microscopy (SEM) images of prints developed with different powders show a range of levels of aggregation of particles. Analytical transmission electron microscopy (TEM) of the fingerprint powder shows TiO{sub 2} particles with a surrounding coating, tens of nanometres thick, consisting of Al and Si rich material. X ray photoelectron spectroscopy (XPS) is used to determine the composition and chemical state of the surface of the powders; with a penetration depth of approximately 10nm, this technique demonstrates differing Ti: Al: Si ratios and oxidation states between the surfaces of different powders. Levels of titanium detected with this technique demonstrate variation in the integrity of the surface coating. The thickness, integrity and composition of the Al/Si-based coating is related to the level of aggregation of TiO{sub 2} particles and efficacy of print development.

Photocatalytic Membrane Reactor for the Removal of C.I. Disperse Red 73

Directory of Open Access Journals (Sweden)

Valentina Buscio

2015-06-01

Full Text Available After the dyeing process, part of the dyes used to color textile materials are not fixed into the substrate and are discharged into wastewater as residual dyes. In this study, a heterogeneous photocatalytic process combined with microfiltration has been investigated for the removal of C.I. Disperse Red 73 from synthetic textile effluents. The titanium dioxide (TiO2 Aeroxide P25 was selected as photocatalyst. The photocatalytic treatment achieved between 60% and 90% of dye degradation and up to 98% chemical oxygen demand (COD removal. The influence of different parameters on photocatalytic degradation was studied: pH, initial photocatalyst loading, and dye concentration. The best conditions for dye degradation were pH 4, an initial dye concentration of 50 mg·L−1, and a TiO2 loading of 2 g·L−1. The photocatalytic membrane treatment provided a high quality permeate, which can be reused.

Nanomaterial Case Studies: Nanoscale Titanium Dioxide in ...

Science.gov (United States)

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.

Molecular and physiological responses to titanium dioxide ...

Science.gov (United States)

- 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

Enhanced photocatalytic activity of nano titanium dioxide coated on ethanol-soluble carbon nanotubes

International Nuclear Information System (INIS)

Fu, Xiaofei; Yang, Hanpei; He, Kuanyan; Zhang, Yingchao; Wu, Junming

2013-01-01

Graphical abstract: Homogenous and dense spreading of TiO 2 on surface modified CNTs and improved photocatalytic performance of TiO 2 was achieved by coupling TiO 2 with ethanol-soluble CNTs. Display Omitted Highlights: ► Ethanol-soluble CNTs were acquired by surface modification. ► Enhanced photoactivity of TiO 2 coated on modified CNTs was obtained. ► Improved activity of TiO 2 is attributed to the intimate contact between TiO 2 and CNTs. ► Dense heterojunctions through Ti–O–CNTs at the interface is proposed. -- Abstract: Surface functionalized carbon nanotubes (CNTs) with ethanol solubility were synthesized and the CNTs–TiO 2 nanocomposites were prepared by coupling of TiO 2 with modified CNTs through a sol–gel method. The as-prepared CNTs and composites were characterized and the composite samples were evaluated for their photocatalytic activity toward the degradation of aqueous methyl orange. It is showed that the acid oxidation of CNTs leads to the embedding of oxygenated functional groups, and as a result, the acid-treated CNTs in turn may serve as chemical reactors for subsequent covalent grafting of octadecylamine. Improved photocatalytic performance of CNTs–TiO 2 composites was obtained, which is mainly attributed to the high dispersion of TiO 2 on ethanol-soluble CNTs and the intimate contact between TiO 2 and CNTs resulted from the dense heterojunctions through the Ti-O-C structure at the interface between TiO 2 and CNTs.

Diffuse Urticarial Reaction Associated with Titanium Dioxide Following Laser Tattoo Removal Treatments.

Science.gov (United States)

Willardson, Hal Bret; Kobayashi, Todd T; Arnold, Jason G; Hivnor, Chad M; Bowen, Casey D

2017-03-01

Local and generalized allergic reactions following laser tattoo removal have been documented, but are rare. To our knowledge, this is the fourth documented case of widespread urticarial eruptions following laser tattoo removal treatment. Unlike previously documented cases, this patient's reaction was found to be associated with titanium dioxide within the tattoo and her symptoms were recalcitrant to medical therapy. A 46-year-old female experienced diffuse urticarial plaques, erythema, and pruritis following multiple laser tattoo removal treatments with an Nd:YAG laser. The systemic allergic reaction was recalcitrant to increasing doses of antihistamines and corticosteroids. The tattoo was finally surgically excised. The excised tissue was analyzed by scanning electron microscopy and energy-dispersive X-ray analysis and contained high levels of titanium dioxide. Two weeks following the excision, and without the use of medical therapy, the patient had complete resolution of her generalized urticaria. Ours is the first documented case of a diffuse urticarial reaction following laser tattoo removal treatments that shows a strong association to titanium dioxide within the tattoo pigment. Herein, we describe a novel surgical approach to treat recalcitrant generalized allergic reaction to tattoo pigment.

The stress caused by nitrite with titanium dioxide nanoparticles under UVA irradiation in human keratinocyte cell

International Nuclear Information System (INIS)

Tu, Min; Huang, Yi; Li, Hai-Ling; Gao, Zhong-Hong

2012-01-01

Highlights: ► Nitrite increased photo-toxicity of nano-TiO 2 on human keratinocyte cells in a dose-dependant manner. ► Morphological study suggested the cell death may be mediated by apoptosis inducing factor. ► Protein nitration was generated in the cells, and the most abundant nitrated protein was identified as cystatin-A. ► Tyr35 was the most likely site to be nitrated in cystatin-A. -- Abstract: Our previous work found that in the presence of nitrite, titanium dioxide nanoparticles can cause protein tyrosine nitration under UVA irradiation in vivo. In this paper, the human keratinocyte cells was used as a skin cell model to further study the photo-toxicity of titanium dioxide nanoparticles when nitrite was present. The results showed that nitrite increased the photo-toxicity of titanium dioxide in a dose-dependant manner, and generated protein tyrosine nitration in keratinocyte cells. Morphological study of keratinocyte cells suggested a specific apoptosis mediated by apoptosis inducing factor. It was also found the main target nitrated in cells was cystatin-A, which expressed abundantly in cytoplasm and functioned as a cysteine protease inhibitor. The stress induced by titanium dioxide with nitrite under UVA irradiation in human keratinocyte cells appeared to trigger the apoptosis inducing factor mediated cell death and lose the inhibition of active caspase by cystatin-A. We conclude that nitrite can bring new damage and stress to human keratinocyte cells with titanium dioxide nanoparticles under UVA irradiation.

Visible light-driven photocatalytic degradation of the organic pollutant methylene blue with hybrid palladium–fluorine-doped titanium oxide nanoparticles

International Nuclear Information System (INIS)

Lázaro-Navas, Sonia; Prashar, Sanjiv; Fajardo, Mariano; Gómez-Ruiz, Santiago

2015-01-01

The synthesis of mesoporous aggregates of titanium oxide nanoparticles (F0) is described using a very cheap and simple synthetic protocol. This consists of the reaction of titanium tetraisopropoxide and a solution of HNO 3 in water (pH 2.0) and subsequent filtration. In addition, fluorine-doped titanium oxides (F1, F2, F5 and F10) were synthesized using the same method, adding increasing amounts of NaF to the reaction mixture (avoiding the use of expensive reagents such as NH 4 F or trifluoroacetic acid). The resulting materials were calcined at different temperatures (500, 600 and 650 °C) giving particles sized between 10 and 20 nm. Furthermore, a hybrid F-doped TiO 2 with supported palladium nanoparticles of ca. 20 nm (F5-500-Pd1) was synthesized by grafting an organometallic palladium(II) salt namely [Pd(cod)Cl 2 ] (cod = 1,5-cyclooctadiene). Photocatalytic studies of the degradation of methylene blue (MB) were carried out under UV light using all the synthesized material (non-doped an F-doped TiO 2 ), observing that the increase in the quantity of fluorine has a positive effect on the photocatalytic activity. F5-500 is apparently the material which has the most convenient structural properties (in terms of surface area and anatase/rutile ratio) and thus a higher photocatalytic activity. The hybrid material F-doped TiO 2 –Pd nanoparticles (F5-500-Pd1) has a lower band gap value than F5-500, and thus photocatalytic degradation of MB under LED visible light was achieved using F5-500-Pd1 as photocatalyst

Ion exchange centres of sorption of alkaline and alkaline-earth cations on hydrated titanium and tin dioxides

International Nuclear Information System (INIS)

Denisova, T.A.; Perekhozheva, T.N.; Sharigin, L.M.; Pletnev, R.N.

1986-01-01

The nature of exchange centres of one- and two-charged cations on hydrated titanium and tin dioxides by means of paramagnetic resonance method is studied. The sorption of cations of Na + , Cs + , Ca 2+ was carried out at 25 and 90 deg C at ph=5.0-10.4 on samples of hydrated titanium dioxide and hydrated tin dioxide, obtained by sol gel method and calcined at 150 deg C and 300 deg C accordingly.

Development of Titanium Dioxide (TiO2 ) Nanocoatings on Food Contact Surfaces and Method to Evaluate Their Durability and Photocatalytic Bactericidal Property.

Science.gov (United States)

Yemmireddy, Veerachandra K; Farrell, Glenn D; Hung, Yen-Con

2015-08-01

Titanium dioxide (TiO2 ) is a well-known photocatalyst for its excellent bactericidal property under UVA light. The purpose of this study was to develop physically stable TiO2 coatings on food contact surfaces using different binding agents and develop methods to evaluate their durability and microbicidal property. Several types of organic and inorganic binders such as polyvinyl alcohol, polyethylene glycol, polyurethane, polycrylic, sodium and potassium silicates, shellac resin, and other commercial binders were used at 1:1 to 1:16 nanoparticle to binder weight ratios to develop a formulation for TiO2 coating on stainless steel surfaces. Among the tested binders, polyurethane, polycrylic, and shellac resin were found to be physically more stable when used in TiO2 coating at 1:4 to 1:16 weight ratio. The physical stability of TiO2 coatings was determined using adhesion strength and scratch hardness tests by following standard ASTM procedures. Further, wear resistance of the coatings was evaluated based on a simulated cleaning procedure used in food processing environments. TiO2 coating with polyurethane at a 1:8 nanoparticle to binder weight ratio showed the highest scratch hardness (1.08 GPa) followed by coating with polycrylic (0.68 GPa) and shellac (0.14 GPa) binders. Three different techniques, namely direct spreading, glass cover-slip, and indented coupon were compared to determine the photocatalytic bactericidal property of TiO2 coatings against Escherichia coli 0157:H7 at 2 mW/cm(2) UVA light intensity. Under the tested conditions, the indented coupon technique was found to be the most appropriate method to determine the bactericidal property of TiO2 coatings and showed a reduction of 3.5 log CFU/cm(2) in 2 h. © 2015 Institute of Food Technologists®

Effect of Titanium dioxide nanoparticles on the flexural strength of polymethylmethacrylate: an in vitro study.

Science.gov (United States)

Harini, P; Mohamed, Kasim; Padmanabhan, T V

2014-01-01

To improve the flexural strength of polymethylmethacrylate (PMMA). To evaluate whether the incorporation of titanium dioxide nanoparticles in polymethylmethacrylate (PMMA) increases the flexural strength and to compare the different concentrations of titanium dioxide nanoparticles and its relation to flexural strength. Study was conducted in Sri Ramachandra University utilizing 40 specimens manufactured from clear heat polymerizing acrylic resin. Forty specimens of clear heat polymerizing acrylic resin of dimensions 65 Χ 10 Χ 3 mm as per ISO 1,567 standardization were fabricated and were grouped into A (CONTROL) with no titanium dioxide (TiO2) nanoparticles, B with 0.5 gms of TiO 2 nanoparticles, C with 1 gm of TiO 2 nanoparticles and D with 2.5 gms of TiO 2 nanoparticles added.The concentrations of titanium dioxide in each group were 1 wt%, 2 wt% and 5 wt%. Universal testing machine INSTRON was used to load at the center of the specimen with a cross head speed of 1.50 mm/min and a span length of 40.00 mm. ANOVA and multiple comparisons are carried out using the independent t-test. The ANOVA result shows that there is a significant difference between the groups with respect to the mean flexural strength. Highest mean flexural strength is observed in Group D, while the lowest is seen in Group A. Independent t-test revealed that there was a statistical significance between Group A and Group D (0.041) and between Group B and Group D (0.028). The results concluded that polymethylmethacrylate reinforced with different concentrations of titanium dioxide nanoparticles showed superior flexural strength than those of normal PMMA.

Titanium dioxide nanoparticles cause genotoxicity in human lung epithelial cells

Science.gov (United States)

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...

Preparation and Characterization of Surface Photocatalytic Activity with NiO/TiO₂ Nanocomposite Structure.

Science.gov (United States)

Chen, Jian-Zhi; Chen, Tai-Hong; Lai, Li-Wen; Li, Pei-Yu; Liu, Hua-Wen; Hong, Yi-You; Liu, Day-Shan

2015-07-13

This study achieved a nanocomposite structure of nickel oxide (NiO)/titanium dioxide (TiO₂) heterojunction on a TiO₂ film surface. The photocatalytic activity of this structure evaluated by decomposing methylene blue (MB) solution was strongly correlated to the conductive behavior of the NiO film. A p -type NiO film of high concentration in contact with the native n -type TiO₂ film, which resulted in a strong inner electrical field to effectively separate the photogenerated electron-hole pairs, exhibited a much better photocatalytic activity than the controlled TiO₂ film. In addition, the photocatalytic activity of the NiO/TiO₂ nanocomposite structure was enhanced as the thickness of the p -NiO film decreased, which was beneficial for the migration of the photogenerated carriers to the structural surface.

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

Science.gov (United States)

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.

Study of the physicochemical properties of the interface between titanium dioxide and various aqueous solutions

International Nuclear Information System (INIS)

Mazilier, C.

1988-01-01

The aim of this work is the study of ion exchange capacity of titanium dioxide in view of high temperature water purification and radioactive effluent processing because of its resistance to heat and radiations. Titanium dioxide is obtained by alkaline hydrolysis of an aqueous solution of Ti (IV) and is characterized by analytical physical chemistry methods. Interface between Ti0 2 and simple aqueous solutions (electrolytes) is more particularly studied by potentiometry [fr

An enhanced photocatalytic response of nanometric TiO2 wrapping of Au nanoparticles for eco-friendly water applications.

Science.gov (United States)

Scuderi, Viviana; Impellizzeri, Giuliana; Romano, Lucia; Scuderi, Mario; Brundo, Maria V; Bergum, Kristin; Zimbone, Massimo; Sanz, Ruy; Buccheri, Maria A; Simone, Francesca; Nicotra, Giuseppe; Svensson, Bengt G; Grimaldi, Maria G; Privitera, Vittorio

2014-10-07

We propose a ground-breaking approach by an upside-down vision of the Au/TiO2 nano-system in order to obtain an enhanced photocatalytic response. The system was synthesized by wrapping Au nanoparticles (∼8 nm mean diameter) with a thin layer of TiO2 (∼4 nm thick). The novel idea of embedding Au nanoparticles with titanium dioxide takes advantage of the presence of metal nanoparticles, in terms of electron trapping, without losing any of the TiO2 exposed surface, so as to favor the photocatalytic performance of titanium dioxide. A complete structural characterization was made by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The remarkable photocatalytic performance together with the stability of the nano-system was demonstrated by degradation of the methylene blue dye in water. The non-toxicity of the nano-system was established by testing the effect of the material on the reproductive cycle of Mytilus galloprovincialis in an aquatic environment. The originally synthesized material was also compared to conventional TiO2 with Au nanoparticles on top. The latter system showed a dispersion of Au nanoparticles in the liquid environment, due to their instability in the aqueous solution that clearly represents an environmental contamination issue. Thus, the results show that nanometric TiO2 wrapping of Au nanoparticles has great potential in eco-friendly water/wastewater purification.

Titanium dioxide, single-walled carbon nanotube composites

Science.gov (United States)

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.

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

Science.gov (United States)

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).

RHEED study of titanium dioxide with pulsed laser deposition

DEFF Research Database (Denmark)

Rasmussen, Inge Lise; Pryds, Nini; Schou, Jørgen

2009-01-01

Reflection high-energy electron diffraction (RHEED) operated at high pressure has been used to monitor the growth of thin films of titanium dioxide (TiO2) on (1 0 0) magnesium oxide (MgO) substrates by pulsed laser deposition (PLD). The deposition is performed with a synthetic rutile TiO2 target...

Antibacterial photocatalytic activity of different crystalline TiO2 phases in oral multispecies biofilm.

Science.gov (United States)

Pantaroto, Heloisa N; Ricomini-Filho, Antonio P; Bertolini, Martinna M; Dias da Silva, José Humberto; Azevedo Neto, Nilton F; Sukotjo, Cortino; Rangel, Elidiane C; Barão, Valentim A R

2018-07-01

Titanium dioxide (TiO 2 ) incorporation in biomaterials is a promising technology due to its photocatalytic and antibacterial activities. However, the antibacterial potential of different TiO 2 crystalline structures on a multispecies oral biofilm remains unknown. We hypothesized that the different crystalline TiO 2 phases present different photocatalytic and antibacterial activities. Three crystalline TiO 2 films were deposited by magnetron sputtering on commercially pure titanium (cpTi), in order to obtain four groups: (1) machined cpTi (control); (2) A-TiO 2 (anatase); (3) M-TiO 2 (mixture of anatase and rutile); (4) R-TiO 2 (rutile). The morphology, crystalline phase, chemical composition, hardness, elastic modulus and surface free energy of the surfaces were evaluated. The photocatalytic potential was assessed by methylene blue degradation assay. The antibacterial activity was evaluated on relevant oral bacteria, by using a multispecies biofilm (Streptococcus sanguinis, Actinomyces naeslundii and Fusobacterium nucleatum) formed on the treated titanium surfaces (16.5h) followed by UV-A light exposure (1h) to generate reactive oxygen species production. All TiO 2 films presented around 300nm thickness and improved the hardness and elastic modulus of cpTi surfaces (p0.05 vs. control). This study brings new insights on the development of extra oral protocols for the photocatalytic activity of TiO 2 in oral biofilm-associated disease. Anatase and mixture-TiO 2 showed antibacterial activity on this oral bacterial biofilm, being promising surface coatings for dental implant components. Copyright © 2018 The Academy of Dental Materials. All rights reserved.

Precipitated nanosized titanium dioxide for electrochemical applications

Energy Technology Data Exchange (ETDEWEB)

Kirillov, S.A. [Joint Department of Electrochemical Energy Systems, 38A Vernadsky Ave., 03142 Kyiv (Ukraine); Institute for Sorption and Problems of Endoecology, 13 Gen. Naumov St., 03164 Kyiv (Ukraine); Lisnycha, T.V. [Institute for Sorption and Problems of Endoecology, 13 Gen. Naumov St., 03164 Kyiv (Ukraine); Chernukhin, S.I. [Joint Department of Electrochemical Energy Systems, 38A Vernadsky Ave., 03142 Kyiv (Ukraine)

2011-02-15

Two types of titanium dioxide samples precipitated from aqueous solutions of titanium tetrachloride are investigated. Crystalline materials are obtained by means of neutralization of TiCl{sub 4} with the solution of an alkali metal hydroxide. The change of the order of mixing leads to amorphous materials. The evolution of the samples upon the thermal treatment is characterized using XRD, SEM, TEM and porosity studies. The application of crystalline TiO{sub 2} as an electrode material in lithium-ion 2016 sample cells enable one to yield specific currents up to 3350 mA g{sup -1}. On the other hand, the thermal treatment of initially amorphous materials does not lead to complete crystallization, and the presence of amorphous TiO{sub 2} is well seen as the so-called capacity behavior of cyclic voltammetry curves. (author)

Visible light-driven photocatalytic degradation of the organic pollutant methylene blue with hybrid palladium–fluorine-doped titanium oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Lázaro-Navas, Sonia; Prashar, Sanjiv; Fajardo, Mariano; Gómez-Ruiz, Santiago, E-mail: santiago.gomez@urjc.es [Universidad Rey Juan Carlos, Departamento de Biología y Geología, Física y Química Inorgánica, ESCET (Spain)

2015-02-15

The synthesis of mesoporous aggregates of titanium oxide nanoparticles (F0) is described using a very cheap and simple synthetic protocol. This consists of the reaction of titanium tetraisopropoxide and a solution of HNO{sub 3} in water (pH 2.0) and subsequent filtration. In addition, fluorine-doped titanium oxides (F1, F2, F5 and F10) were synthesized using the same method, adding increasing amounts of NaF to the reaction mixture (avoiding the use of expensive reagents such as NH{sub 4}F or trifluoroacetic acid). The resulting materials were calcined at different temperatures (500, 600 and 650 °C) giving particles sized between 10 and 20 nm. Furthermore, a hybrid F-doped TiO{sub 2} with supported palladium nanoparticles of ca. 20 nm (F5-500-Pd1) was synthesized by grafting an organometallic palladium(II) salt namely [Pd(cod)Cl{sub 2}] (cod = 1,5-cyclooctadiene). Photocatalytic studies of the degradation of methylene blue (MB) were carried out under UV light using all the synthesized material (non-doped an F-doped TiO{sub 2}), observing that the increase in the quantity of fluorine has a positive effect on the photocatalytic activity. F5-500 is apparently the material which has the most convenient structural properties (in terms of surface area and anatase/rutile ratio) and thus a higher photocatalytic activity. The hybrid material F-doped TiO{sub 2}–Pd nanoparticles (F5-500-Pd1) has a lower band gap value than F5-500, and thus photocatalytic degradation of MB under LED visible light was achieved using F5-500-Pd1 as photocatalyst.

Suppressing the Photocatalytic Activity of TiO2 Nanoparticles by Extremely Thin Al2O3 Films Grown by Gas-Phase Deposition at Ambient Conditions

NARCIS (Netherlands)

Guo, J.; Bui, H.V.; Valdesueiro Gonzalez, D.; Yuan, Shaojun; Liang, Bin; van Ommen, J.R.

2018-01-01

This work investigated the suppression of photocatalytic activity of titanium dioxide (TiO2) pigment powders by extremely thin aluminum oxide (Al2O3) films deposited via an atomic-layer-deposition-type process using trimethylaluminum (TMA) and H2O as precursors. The deposition was performed on

Hydrothermal Synthesis of Nitrogen-Doped Titanium Dioxide and Evaluation of Its Visible Light Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Junjie Qian

2012-01-01

Full Text Available Nitrogen-doped titanium dioxide (N-doped TiO2 photocatalyst was synthesized from nanotube titanic acid (denoted as NTA; molecular formula H2Ti2O5·H2O precursor via a hydrothermal route in ammonia solution. As-synthesized N-doped TiO2 catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffuse reflectance spectrometry, X-ray photoelectron spectroscopy, electron spin resonance spectrometry and Fourier transform infrared spectrometry. It was found that nanotube ammonium titanate (NAT was produced as an intermediate during the preparation of N-doped TiO2 from NTA, as evidenced by the N1s X-ray photoelectron spectroscopic peak of NH4 + at 401.7 eV. The catalyst showed much higher activities to the degradation of methylene blue and p-chlorophenol under visible light irradiation than Degussa P25. This could be attributed to the enhanced absorption of N-doped TiO2 in visible light region associated with the formation of single-electron-trapped oxygen vacancies and the inhibition of recombination of photo-generated electron-hole pair by doped nitrogen.

Development of a Fabrication Process Using Suspension Plasma Spray for Titanium Oxide Photovoltaic Device

Directory of Open Access Journals (Sweden)

Hsian Sagr Hadi A

2017-03-01

Full Text Available In order to reduce the high costs of conventional materials, and to reduce the power necessary for the deposition of titanium dioxide, titanium tetrabutoxide has been developed in the form of a suspension of TiO2 using water instead of expensive ethanol. To avoid sedimentation of hydroxide particles in the suspension, mechanical milling of the suspension was conducted in order to create diffusion in colloidal suspension before using it as feedstock. Consequently, through the creation of a colloidal suspension, coating deposition was able to be conducted without sedimentation of the hydroxide particles in the suspension during the deposition process. Though an amorphous as-deposited coating was able to be deposited, through post heat treatment at 630 °C for 60 min, the chemical structure became anatase rich. In addition, it was confirmed that the post heat treated anatase rich coating had enough photo-catalytic activity to decolor methylene-blue droplets. From these results, this technique was found to have high potential in the low cost photo-catalytic titanium coating production process.

In-Flight Formation of Nano-Crystalline Titanium Dioxide Powder in a Plasma Jet and Its Characterization

International Nuclear Information System (INIS)

Ananthapadmanabhan, P. V.; Thiyagarajan, T. K.; Sreekumar, K. P.; Vijay, M.; Selvarajan, V.; Yu, Jiaguo; Liu, Shengwei

2010-01-01

Nanocrystalline titanium dioxide powder was synthesized by in-flight oxidation of titanium dihydride (TiH 2 ) powder in a thermal plasma jet. TiH 2 powder was injected into the thermal plasma jet and allowed to react with oxygen injected downstream the jet. Characterization of the powder by various analytical tools indicated that the powder consisted of nano-sized titanium dioxide particles consisting predominantly of the anatase phase. It is suggested that the thermo-chemistry of the oxidation process contributes significantly to the formation of nano-sized titania. The large energy released during the oxidation process dissociates the TiO 2 particles into TiO (g) and titanium vapour, which recombine downstream with oxygen and form nano particles of TiO 2 .

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

Science.gov (United States)

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).

Growth mechanism of titanium dioxide nanowires for dye-sensitized solar cells

International Nuclear Information System (INIS)

Boercker, J E; Enache-Pommer, E; Aydil, E S

2008-01-01

Mesoporous films made of titanium dioxide nanowires are desirable for dye-sensitized solar cells because nanowires provide direct conduction pathways for photogenerated electrons. Anatase titanium dioxide nanowires with polycrystalline microstructure were synthesized on titanium foil using a three-step process. First, the top surface of the titanium foil was transformed to Na 2 Ti 2 O 4 (OH) 2 nanotubes through hydrothermal oxidation in NaOH. Next, the Na 2 Ti 2 O 4 (OH) 2 nanotubes were converted to H 2 Ti 2 O 4 (OH) 2 nanotubes by ion exchange. Finally, the H 2 Ti 2 O 4 (OH) 2 nanotubes were converted to polycrystalline anatase nanowires through a topotactic transformation. The film morphology evolution, crystal structure transformations and growth mechanism are described in detail. Titanium foil reacts with NaOH to form Na 2 Ti 2 O 4 (OH) 2 sheets, which exfoliate and spiral into nanotubes. The Na 2 Ti 2 O 4 (OH) 2 nanotubes are immersed in HCl solution to replace the Na + ions with H + ions. During the topotactic transformation of H 2 Ti 2 O 4 (OH) 2 nanotubes to anatase TiO 2 nanowires, the sheets made of edge bonded TiO 6 octahedra in the H 2 Ti 2 O 4 (OH) 2 nanotubes dehydrate and move towards each other to form anatase crystals oriented along the nanotube axis which creates a polycrystalline nanowire. These mesoporous TiO 2 nanowire films were suitable for use as dye-sensitized solar cell photoanodes

Titanium dioxide (TIO2) thin film and plasma properties in RF magnetron sputtering

International Nuclear Information System (INIS)

Ali, Riyaz Ahmad Mohamed; Nayan, Nafarizal

2013-01-01

Lately, titanium dioxide (TiO 2 ) films with anatase crystalline property received numerous attentions as unique material properties. There are wide applications of TiO 2 thin film such as for photocatalytic application in solar cell. In the present study, radio frequency (RF) magnetron sputtering technique has been used to produce high dense, homogeneously controllable film layer at low deposition temperature using titanium (Ti) target. The diameter of the Ti target is 3 inch with fixed discharge power of 400W. Magnetron sputtering plasma has been produced in high purity 99.99% Argon (Ar) and 99.99% Oxygen (O 2 ) environment pressure ranging from 5 to 20 mTorr. The TiO2 were growth on silicon and glass substrates. Substrate temperature during deposition was kept constant at 400°C. The distance between target and substrate holder was maintain at 14 cm with rotation of 10 rotation-per-minutes. Our X-ray diffraction result, shows anatase crystalline successfully formed with characterization peaks of plane (101) at 2θ = 25.28°, plane (202) at 2θ = 48.05° and plane (211) at 2θ = 55.06°. In addition, it is our interest to study the plasma properties and optical spectrum of Ti, Ti+ , O- , ArM and Ar+ in the chamber during the deposition process. Result of emission line intensities, electron density and temperature from optical spectroscope and Langmuir probe will be discuss further during the workshop. This works were supported by Graduate Incentive Scheme of Universiti Tun Hussein Onn Malaysia (UTHM) and Fundamental Research Grant Scheme of Ministry of Higher Education, Malaysia. (author)

TiO{sub 2} Processed by pressurized hot solvents as a novel photocatalyst for photocatalytic reduction of carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Reli, Martin, E-mail: martin.reli@vsb.cz [Institute of Environmental Technology, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava (Czech Republic); Kobielusz, Marcin [Faculty of Chemistry, Jagiellonian University in Kraków, ul. Ingardena 3, 30-060 Kraków (Poland); Matějová, Lenka [Institute of Environmental Technology, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava (Czech Republic); Daniš, Stanislav [Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Macyk, Wojciech [Centre ENET, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava (Czech Republic); Obalová, Lucie [Institute of Environmental Technology, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava (Czech Republic); Kuśtrowski, Piotr; Rokicińska, Anna [Faculty of Chemistry, Jagiellonian University in Kraków, ul. Ingardena 3, 30-060 Kraków (Poland); Kočí, Kamila [Institute of Environmental Technology, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava (Czech Republic); Centre ENET, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava (Czech Republic)

2017-01-01

Highlights: • Synthesis of anatase-brookite TiO{sub 2} photocatalysts has been described. • The materials photocatalyze carbon dioxide reduction to methane. • The photoactivity of the synthesized composites has been compared with the activity of anatase-rutile material (P25). • The influence of electronic structure on photocatalytic activity has been discussed. - Abstract: Anatase-brookite TiO{sub 2} photocatalysts were prepared by the sol-gel process controlled within reverse micelles and processing by pressurized hot solvents–water/methanol/water (TiO{sub 2}(M)) and water/ethanol/water (TiO{sub 2}(E)), as an unconventional alternative to common calcination. The main goal of this work was to prepare anatase-brookite mixtures by processing by two different alcohols (methanol and ethanol) and evaluate the influence of the alcohol on the photocatalytic activity. Prepared photocatalysts were characterized by organic elemental analysis, nitrogen physisorption, XRD, UV–vis, photoelectrochemical and spectroelectrochemical measurements and XPS. The prepared photocatalysts efficiency was tested on the photocatalytic reduction of carbon dioxide and compared with commercial TiO{sub 2} Evonik P25. Both prepared nanocomposites were more efficient towards methane production but Evonik P25 was the most efficient towards hydrogen generated through water splitting. The higher performance of anatase-brookite mixture towards methane production can be explained by (i) a higher photocatalytic activity of brookite than rutile; (ii) a large surface area of anatase-brookite composites enabling better carbon dioxide adsorption; (iii) the photoinduced electron transfer from the brookite conduction band to the anatase conduction band. On the other hand, a higher production of hydrogen in the presence of Evonik P25 is caused by a better charge separation in anatase-rutile than anatase-brookite phase compositions. TiO{sub 2}(M) appeared more active than TiO{sub 2}(E) in the

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

Science.gov (United States)

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.

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

Science.gov (United States)

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 ...

Erbium diffusion in titanium dioxide

Directory of Open Access Journals (Sweden)

Louise Basse

2017-04-01

Full Text Available The diffusivity of erbium in the anatase phase of titanium dioxide (TiO2 has been studied for various temperatures ranging from 800 °C to 1, 000 °C. Samples of TiO2, with a 10 nm thick buried layer containing 0.5 at% erbium, were fabricated by radio-frequency magnetron sputtering and subsequently heat treated. The erbium concentration profiles were measured by secondary ion mass spectrometry, allowing for determination of the temperature-dependent diffusion coefficients. These were found to follow an Arrhenius law with an activation energy of ( 2.1 ± 0.2 eV. X-ray diffraction revealed that the TiO2 films consisted of polycrystalline grains of size ≈ 100 nm.

PHOTOCATALYTIC REMOVAL OF TR I- AND HEXA-VALENT CHROMIUM IONS FROM CHROME-ELECTROPL ATING WASTEWATER

OpenAIRE

Puangrat Kajitvichyanukul; Chulaluck Changul

2017-01-01

A novel technique based on photocatalysis was applied to eliminate chromium ions, a toxic hazardous environmental pollutant. The photoreduction of each species of chromium (total, hexavalent, and trivalent chromiums) from chrome-electroplating wastewater was investigated using a titanium dioxide suspension under irradiation by a low-pressure mercury lamp. The initial concentration of total chromium was 300 mg/l. The applied conditions were the direct photocatalytic reduction process at pH 3.6...

Characterization of nanoparticles released during construction of photocatalytic pavements using engineered nanoparticles

International Nuclear Information System (INIS)

Dylla, Heather; Hassan, Marwa M.

2012-01-01

With the increasing use of titanium dioxide (TiO 2 ) nanoparticles in self-cleaning materials such as photocatalytic concrete pavements, the release of nanoparticles into the environment is inevitable. Nanoparticle concentration, particle size, surface area, elemental composition, and surface morphology are pertinent to determine the associated risks. In this study, the potential of exposure to synthetic nanoparticles released during construction activities for application of photocatalytic pavements was measured during laboratory-simulated construction activities of photocatalytic mortar overlays and in an actual field application of photocatalytic spray coat. A scanning mobility particle sizer system measured the size distribution of nanoparticles released during laboratory and field activities. Since incidental nanoparticles are released during construction activities, nanoparticle emissions were compared to those from similar activities without nano-TiO 2 . Nanoparticle counts and size distribution suggest that synthetic nanoparticles are released during application of photocatalytic pavements. In order to identify the nanoparticle source, nanoparticles were also collected for offline characterization using transmission electron microscopy. However, positive identification of synthetic nanoparticles was not possible due to difficulties in obtaining high-resolution images. As a result, further research is recommended to identify nanoparticle composition and sources.

Preparation and photocatalytic activity of chemically-bonded phosphate ceramics containing TiO2

Science.gov (United States)

Martins, Monize Aparecida; de Lima, Bruna de Oliveira; Ferreira, Leticia Patrício; Colonetti, Emerson; Feltrin, Jucilene; De Noni, Agenor

2017-05-01

Titanium dioxide was incorporated into chemically-bonded phosphate ceramic for use as photocatalytic inorganic coating. The coatings obtained were applied to unglazed ceramic tiles and cured at 350 °C. The surfaces were characterized by photocatalytic activity, determined in aqueous medium, based on the degradation of methylene blue dye. The effects of the percentage of TiO2 and the thickness of the layer on the photocatalytic efficiency were evaluated. The influence of the incorporation of TiO2 on the consolidation of the phosphate matrix coating was investigated using the wear resistance test. The crystalline phases of the coatings obtained were determined by XRD. The microstructure of the surfaces was analyzed by SEM. The thermal curing treatment did not cause a phase transition from anatase to rutile. An increase in the photocatalytic activity of the coating was observed with an increase in the TiO2 content. The dye degradation indices ranged from 14.9 to 44.0%. The photocatalytic efficiency was not correlated with the thickness of the coating layer deposited. The resistance to wear decreased with an increase in the TiO2 content. Comparison with a commercial photocatalytic ceramic coating indicated that there is a range of values for the TiO2 contents which offer potential for photocatalytic applications.

Characterization of biodegradable polycaprolactone containing titanium dioxide micro and nanoparticles

Czech Academy of Sciences Publication Activity Database

Govorčin Bajsić, E.; Ocelić Bulatović, V.; Šlouf, Miroslav; Šitum, Ana

2014-01-01

Roč. 8, č. 7 (2014), s. 536-540 ISSN 2010-376X R&D Projects: GA TA ČR TE01020118 Institutional support: RVO:61389013 Keywords : morphology * polycaprolactone * thermal properties Subject RIV: EA - Cell Biology http://waset.org/Publication/characterization-of-biodegradable-polycaprolactone-containing-titanium-dioxide-micro-and-nanoparticles/9998694

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

Science.gov (United States)

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.

Turkevich method for silver/titanium dioxide nanoparticles with antimicrobial application in polymers systems

International Nuclear Information System (INIS)

Olyveira, Gabriel Molina de; Pessan, Luiz Antonio

2009-01-01

Titanium dioxide nanoparticles were covered with silver nanoparticles using Turkevich Method or citrate reduction method. Silver and titanium dioxide has proved antimicrobial properties then the nanocomposite can be successful incorporated in polymer systems. Silver nitrate was reduced by sodium citrate in the presence of poly(vinyl pyrrolidone)(PVP) resulting in nano-Ag/TiO 2 stabilized suspension. It was tested ammonia hydroxide in the synthesis to avoid the nanoparticles growth. The Ag/TiO 2 nanoparticles were characterized with X-ray diffraction (XRD), Scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS). The best system of coloidal nanoparticles was that one with Poly(vinyl pyrrolidone) and ammonia in the synthesis. (author)

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

Science.gov (United States)

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...

PHOTOCATALYTIC REMOVAL OF TR I- AND HEXA-VALENT CHROMIUM IONS FROM CHROME-ELECTROPL ATING WASTEWATER

Directory of Open Access Journals (Sweden)

Puangrat Kajitvichyanukul

2017-11-01

Full Text Available A novel technique based on photocatalysis was applied to eliminate chromium ions, a toxic hazardous environmental pollutant. The photoreduction of each species of chromium (total, hexavalent, and trivalent chromiums from chrome-electroplating wastewater was investigated using a titanium dioxide suspension under irradiation by a low-pressure mercury lamp. The initial concentration of total chromium was 300 mg/l. The applied conditions were the direct photocatalytic reduction process at pH 3.65 and the indirect photocatalytic reduction with added hole scavengers at the same solution pH. Results from both processes were comparatively discussed. Result show that chromium was not efficiently removed by direct photoreduction. In contrast, with the adding of hole scavengers, which were formate ions, the photoreduction of chromium was very favorable. Both hexavalent and trivalent chromiums were efficiently removed. The photocatalytic mechanism is purposed in this study.

Preparation and Characterization of Surface Photocatalytic Activity with NiO/TiO2 Nanocomposite Structure

Directory of Open Access Journals (Sweden)

Jian-Zhi Chen

2015-07-01

Full Text Available This study achieved a nanocomposite structure of nickel oxide (NiO/titanium dioxide (TiO2 heterojunction on a TiO2 film surface. The photocatalytic activity of this structure evaluated by decomposing methylene blue (MB solution was strongly correlated to the conductive behavior of the NiO film. A p-type NiO film of high concentration in contact with the native n-type TiO2 film, which resulted in a strong inner electrical field to effectively separate the photogenerated electron-hole pairs, exhibited a much better photocatalytic activity than the controlled TiO2 film. In addition, the photocatalytic activity of the NiO/TiO2 nanocomposite structure was enhanced as the thickness of the p-NiO film decreased, which was beneficial for the migration of the photogenerated carriers to the structural surface.

Nanostructured titanium dioxide: a control of crystallite size and content of polymorphic phases; Nanoestrutura de dioxido de titanio: controle do tamanho de cristalitos e teor das fases polimorficas

Energy Technology Data Exchange (ETDEWEB)

Boery, Mirella N. de O.; Ono, Eduardo; Manfrim, Tarcio P.; Santos, Juliana S.; Suzuki, Carlos K., E-mail: miboery@fem.unicamp.b [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

2010-07-01

TiO{sub 2} (titanium dioxide) powders and nanoparticles have been largely used in toners and cosmetics. Nowadays, they are mainly focused in photocatalysis, antibacterial coatings, dye-sensitized solar cells, etc. The efficiency is related to photocatalytic properties of TiO{sub 2} nanoparticles, such as crystallite size and phase (anatasio/rutile). In this research, flame aerosol method was used to synthesize TiO{sub 2} nanoparticles by hydrolysis and oxidation of TiCl{sub 4} (titanium tetrachloride). The oxy-hydrogen flame was provided by a five concentric nozzle silica burner. X-ray diffraction was used to identify each TiO{sub 2} nanoparticles phase and scanning electron microscopy was used to observe the size and morphology of nanoparticles. Pure anatase was obtained with H{sub 2}/O{sub 2} ratio {<=} 1.0, and up to 52 wt% of rutile was obtained with H{sub 2}/O{sub 2} ratio > 2.0. Anatase crystal grain size varied from 25 to 38 nm, estimated by Scherrer formula.(author)

Microwave synthesis of Titanium Dioxide nanotubes for use in water treatment

CSIR Research Space (South Africa)

Sikhwivhilu, L

2010-09-01

Full Text Available various methods have been used to synthesise Titanium Dioxide (TiO2) (also known as Titania) nanoparticles hydrothermal synthesis in the presence of a base solution, has proved to be an effective approach to prepare 1D nanostructures of TiO2...

Synthesis and electrochemical evaluation of an amorphous titanium dioxide derived from a solid state precursor

Science.gov (United States)

Joyce, Christopher D.; McIntyre, Toni; Simmons, Sade; LaDuca, Holly; Breitzer, Jonathan G.; Lopez, Carmen M.; Jansen, Andrew N.; Vaughey, J. T.

Titanium oxides are an important class of lithium-ion battery electrodes owing to their good capacity and stability within the cell environment. Although most Ti(IV) oxides are poor electronic conductors, new methods developed to synthesize nanometer scale primary particles have achieved the higher rate capability needed for modern commercial applications. In this report, the anionic water stable titanium oxalate anion [TiO(C 2O 4) 2] 2- was isolated in high yield as the insoluble DABCO (1,4-diazabicyclo[2.2.2]octane) salt. Powder X-ray diffraction studies show that the titanium dioxide material isolated after annealing in air is initially amorphous, converts to N-doped anatase above 400 °C, then to rutile above 600 °C. Electrochemical studies indicate that the amorphous titanium dioxide phase within a carbon matrix has a stable cycling capacity of ∼350 mAh g -1. On crystallizing at 400 °C to a carbon-coated anatase the capacity drops to 210 mAh g -1, and finally upon carbon burn-off to 50 mAh g -1. Mixtures of the amorphous titanium dioxide and Li 4Ti 5O 12 showed a similar electrochemical profile and capacity to Li 4Ti 5O 12 but with the addition of a sloping region to the end of the discharge curve that could be advantageous for determining state-of-charge in systems using Li 4Ti 5O 12.

Enhanced photocatalytic degradation of Safranin-O by heterogeneous nanoparticles for environmental applications

International Nuclear Information System (INIS)

El-Kemary, Maged; Abdel-Moneam, Yasser; Madkour, Metwally; El-Mehasseb, Ibrahim

2011-01-01

Nanostructure titanium dioxide (TiO 2 ) has been synthesized by hydrolysis of titanium tetrachloride in aqueous solution and Ag-TiO 2 nanoparticles were synthesized by photoreduction method. The resulting materials were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier-transform infrared (FT-IR) and UV-vis absorption spectroscopy. The experimental results showed that the sizes of the synthesized TiO 2 and Ag-TiO 2 particles are in the range of 1.9-3.2 nm and 2-10 nm, respectively. Moreover, Ag-TiO 2 nanoparticles exhibit enhanced photocatalytic activity on photodegradation of Safranin-O (SO) dye as compared to pure TiO 2 . The positive effect of silver on the photocatalytic activity of TiO 2 may be explained by its ability to trap electrons. This process reduces the recombination of light generated electron-hole pairs at TiO 2 surface and therefore enhances the photocatalytic activity of the synthesized TiO 2 nanoparticles. The effects of initial dye and nanoparticle concentrations on the photocatalytic activity have been studied and the results demonstrate that the dye photodegradation follows pseudo-first-order kinetics. The observed maximum degradation efficiency of SO is about 60% for TiO 2 and 96% for Ag-TiO 2 . - Research highlights: → Ag-TiO 2 nanoparticles exhibit enhanced photocatalytic activity on photodegradation of Safranin-O (SO) dye as compared to pure TiO 2 . → Dye photodegradation follows pseudo-first-order kinetics. → Observed maximum degradation efficiency of SO is about 60% for TiO 2 and 96% for Ag-TiO 2 .

Defective TiO2 with oxygen vacancies: synthesis, properties and photocatalytic applications

Science.gov (United States)

Pan, Xiaoyang; Yang, Min-Quan; Fu, Xianzhi; Zhang, Nan; Xu, Yi-Jun

2013-04-01

Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications.Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the

Microwave-assisted ionothermal synthesis of nanostructured anatase titanium dioxide/activated carbon composite as electrode material for capacitive deionization

International Nuclear Information System (INIS)

Liu, Po-I; Chung, Li-Ching; Shao, Hsin; Liang, Teh-Ming; Horng, Ren-Yang; Ma, Chen-Chi M.; Chang, Min-Chao

2013-01-01

The nanostructured anatase titanium dioxide/activated carbon composite material for capacitive deionization electrode was prepared in a short time by a lower temperature two-step microwave-assisted ionothermal (sol–gel method in the presence of ionic liquid) synthesis method. This method includes a reaction and a crystallization step. In the crystallization step, the ionic liquid plays a hydrothermal analogy role in driving the surface anatase crystallization of amorphous titanium dioxide nanoparticles formed in the reaction step. The energy dispersive spectroscopic study of the composite indicates that the anatase titanium dioxide nanoparticles are evenly deposited in the matrix of activated carbon. The electrochemical property of the composite electrode was investigated. In comparison to the pristine activated carbon electrode, higher specific capacitance was observed for the nanostructured anatase titanium dioxide/activated carbon composite electrode, especially when the composite was prepared with a molar ratio of titanium tetraisopropoxide/H 2 O equal to 1:15. Its X-ray photoelectron spectroscopic result indicates that it has the highest amount of Ti-OH. The Ti-OH group can enhance the wetting ability and the specific capacitance of the composite electrode. The accompanying capacitive deionization result indicates that the decay of electrosorption capacity of this composite electrode is insignificant after five cycle tests. It means that the ion electrosorption–desorption becomes a reversible process

Toxicity Assessment of Six Titanium Dioxide Nanoparticles in Human Epidermal Keratinocytes

Science.gov (United States)

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...

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

Science.gov (United States)

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 ...

Photocatalytic, Antimicrobial and Biocompatibility Features of Cotton Knit Coated with Fe-N-Doped Titanium Dioxide Nanoparticles

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Miruna Silvia Stan

2016-09-01

Full Text Available Our research was focused on the evaluation of the photocatalytic and antimicrobial properties, as well as biocompatibility of cotton fabrics coated with fresh and reused dispersions of nanoscaled TiO2-1% Fe-N particles prepared by the hydrothermal method and post-annealed at 400 °C. The powders were characterized by X-ray diffraction (XRD, Mössbauer spectroscopy and X-ray photoelectron spectroscopy. The textiles coated with doped TiO2 were characterized by scanning electron microscopy and energy dispersive X-ray analyses, and their photocatalytic effect by trichromatic coordinates of the materials stained with methylene blue and coffee and exposed to UV, visible and solar light. The resulting doped TiO2 consists of a mixture of prevailing anatase phase and a small amount (~15%–20% of brookite, containing Fe3+ and nitrogen. By reusing dispersions of TiO2-1% Fe-N, high amounts of photocatalysts were deposited on the fabrics, and the photocatalytic activity was improved, especially under visible light. The treated fabrics exhibited specific antimicrobial features, which were dependent on their composition, microbial strain and incubation time. The in vitro biocompatibility evaluation on CCD-1070Sk dermal fibroblasts confirmed the absence of cytotoxicity after short-term exposure. These results highlight the potential of TiO2-1% Fe-N nanoparticles for further use in the development of innovative self-cleaning and antimicrobial photocatalytic cotton textiles. However, further studies are required in order to assess the long-term skin exposure effects and the possible particle release due to wearing.

Biopolymer Doped with Titanium Dioxide Superhydrophobic Photocatalysis as Self-Clean Coating for Lightweight Composite

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Anika Zafiah M. Rus

2013-01-01

Full Text Available The development of a lightweight composite (LC based on Portland cement concrete with waste lightweight aggregate (WLA additive was carried out to improve the sustainability and environmental impact and to offer potential cost savings without sacrificing strength. Treatment of the surface of the LC exposed to environmental attack by coating with biopolymer based on waste cooking oil doped with titanium dioxide photocatalysis (TOP with superhydrophilic property was found to affect the mechanical properties of the LC in a systematic way. The results of compressive strength showed that the composite achieved the minimum required strength for lightweight construction materials of 17.2 MPa. Scratch resistance measurements showed that the highest percentages loading of superhydrophilic particles (up to 2.5% of biomonomer weight for LC's surface coating gave the highest scratch resistance while the uncoated sample showed the least resistances. Scanning electron microscope (SEM pictures revealed the difference between the surface roughness for LC with and without TOP coating. TOP is also formulated to provide self-cleaning LC surfaces based on two principal ways: (1 the development by coating the LC with a photocatalytic superhydrophilic, (2 if such a superhydrophilic is illuminated by light, the grease, dirt, and organic contaminants will be decomposed and can easily be swept away by rain.

Growth mechanism of titanium dioxide nanowires for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Boercker, J E; Enache-Pommer, E; Aydil, E S [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455 (United States)], E-mail: aydil@umn.edu

2008-03-05

Mesoporous films made of titanium dioxide nanowires are desirable for dye-sensitized solar cells because nanowires provide direct conduction pathways for photogenerated electrons. Anatase titanium dioxide nanowires with polycrystalline microstructure were synthesized on titanium foil using a three-step process. First, the top surface of the titanium foil was transformed to Na{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2} nanotubes through hydrothermal oxidation in NaOH. Next, the Na{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2} nanotubes were converted to H{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2} nanotubes by ion exchange. Finally, the H{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2} nanotubes were converted to polycrystalline anatase nanowires through a topotactic transformation. The film morphology evolution, crystal structure transformations and growth mechanism are described in detail. Titanium foil reacts with NaOH to form Na{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2} sheets, which exfoliate and spiral into nanotubes. The Na{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2} nanotubes are immersed in HCl solution to replace the Na{sup +} ions with H{sup +} ions. During the topotactic transformation of H{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2} nanotubes to anatase TiO{sub 2} nanowires, the sheets made of edge bonded TiO{sub 6} octahedra in the H{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2} nanotubes dehydrate and move towards each other to form anatase crystals oriented along the nanotube axis which creates a polycrystalline nanowire. These mesoporous TiO{sub 2} nanowire films were suitable for use as dye-sensitized solar cell photoanodes.

Photocatalytic degradation of selected herbicides in aqueous suspensions of doped titania under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Sojic, Daniela V., E-mail: daniela.sojic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Despotovic, Vesna N., E-mail: vesna.despotovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Abazovic, Nadica D., E-mail: kiki@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Comor, Mirjana I., E-mail: mirjanac@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Abramovic, Biljana F., E-mail: biljana.abramovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia)

2010-07-15

The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light ({lambda} {>=} 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO{sub 2} (rutile/anatase) and of the most frequently used TiO{sub 2} Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.

Photocatalytic Degradation of Aniline Using TiO2 Nanoparticles in a Vertical Circulating Photocatalytic Reactor

Directory of Open Access Journals (Sweden)

F. Shahrezaei

2012-01-01

Full Text Available Photocatalytic degradation of aniline in the presence of titanium dioxide (TiO2 and ultraviolet (UV illumination was performed in a vertical circulating photocatalytic reactor. The effects of catalyst concentration (0–80 mg/L, initial pH (2–12, temperature (293–323 K, and irradiation time (0–120 min on aniline photodegradation were investigated in order to obtain the optimum operational conditions. The results reveal that the aniline degradation efficiency can be effectively improved by increasing pH from 2 to 12 and temperature from 313 to 323 K. Besides, the effect of temperature on aniline photo degradation was found to be unremarkable in the range of 293–313 K. The optimum catalyst concentration was about 60 mg/L. The Langmuir Hinshelwood kinetic model could successfully elucidate the effects of the catalyst concentration, pH, and temperature on the rate of heterogeneous photooxidation of aniline. The data obtained by applying the Langmuir Hinshelwood treatment are consistent with the available kinetic parameters. The activated energy for the photocatalytic degradation of aniline is 20.337 kj/mol. The possibility of the reactor use in the treatment of a real petroleum refinery wastewater was also investigated. The results of the experiments indicated that it can therefore be potentially applied for the treatment of wastewater contaminated by different organic pollutants.

Photocatalytic degradation of organic contaminants under solar light using carbon dot/titanium dioxide nanohybrid, obtained through a facile approach

International Nuclear Information System (INIS)

Hazarika, Deepshikha; Karak, Niranjan

2016-01-01

Highlights: • Nitrogen containing carbon dot and carbon dot/TiO 2 nanohybrid (CD@TiO 2 ) are synthesized without any additional doping of passivating agent. • The photocatalytic efficacy of CD@TiO 2 is found to be the best as compared to the bare TiO 2 , CD and nanohybrid of TiO 2 in presence of carbon dot. • Up-conversion luminescence of CD promotes the degradation activity of synthesized CD@TiO 2 under visible light. • The hazardous contaminants like phenol, benzene and pesticide are efficiently degraded by CD@TiO 2 under normal sunlight. - Abstract: In the present study, a novel, simple and green method was developed to synthesize highly luminescent nitrogen containing carbon dot (CD) using carbon resources like bio-based citric acid and glycerol in the presence of cost free cow urine. The as-synthesized CD showed exciting wavelength dependent down- and up-conversion flourescence properties. To utilize the advantage of up-conversion flourescence, a nanohybrid (CD@TiO 2 ) was synthesized from the above carbon resources and titanium butoxide through a facile one pot single step hydrothermal protocol. Nanomaterials like bare TiO 2 and nanohybrid of TiO 2 in presence of CD (CD/TiO 2 ) were also synthesized for comparison purpose. The optical properties and structural characteristics of the prepared CD, bare TiO 2 , CD@TiO 2 and CD/TiO 2 were examined by Fourier transform infrared (FTIR), UV–vis and fluorescence spectroscopic, scanning electron microscopic (SEM), transmission electron microscopic (TEM) and X-ray diffraction (XRD) studies. The elemental compositions of bare CD and CD@TiO 2 nanohybrid were obtained from EDX analyses. The poor crystalline nature and narrow distribution of spherical CD and anatase form of TiO 2 were confirmed from XRD and TEM studies. Amongst the studied nanomaterials, CD@TiO 2 exhibited the most promising photocatalytic degradation of organic pollutants like benzene and phenol as well as an anthrogenic pesticide under sunlight.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Study of effect of chromium on titanium dioxide phase transformation ...

Indian Academy of Sciences (India)

Administrator

Study of effect of chromium on titanium dioxide phase transformation by A Bellifa (pp 669–677). Figure S1. Structural ... 4 × 1⋅9486; 2 × 1⋅9799. Octahedral packing. 2 × 2 shared edges. 8 free edges. 3 shared edges. 4 corners. 5 free edges. 2 parallel shared edges. 2 corners. 10 free edges. O. O. Coordination scheme.

Highly photocatalytic TiO_2 interconnected porous powder fabricated by sponge-templated atomic layer deposition

International Nuclear Information System (INIS)

Pan, Shengqiang; Zhao, Yuting; Huang, Gaoshan; Li, Menglin; Mei, Yongfeng; Wang, Jiao; Zheng, Lirong; Baunack, Stefan; Schmidt, Oliver G; Gemming, Thomas

2015-01-01

A titanium dioxide (TiO_2) interconnected porous structure has been fabricated by means of atomic layer deposition of TiO_2 onto a reticular sponge template. The obtained freestanding TiO_2 with large surface area can be easily taken out of the water to solve a complex separation procedure. A compact and conformal nanocoating was evidenced by morphologic characterization. A phase transition, as well as production of oxygen vacancies with increasing annealing temperature, was detected by x-ray diffraction and x-ray photoelectron spectroscopy, respectively. The photocatalytic experimental results demonstrated that the powder with appropriate annealing treatment possessed excellent photocatalytic ability due to the co-action of high surface area, oxygen vacancies and the optimal crystal structure. (paper)

Use of hydrous titanium dioxide as potential sorbent for the removal of manganese from water

Directory of Open Access Journals (Sweden)

Ramakrishnan Kamaraj

2014-12-01

Full Text Available This research article deals with an electrosynthesis of hydrous titanium dioxide by anodic dissolution of titanium sacrificial anodes and their application for the adsorption of manganese from aqueous solution. Titanium sheet was used as the sacrificial anode and galvanized iron sheet was used as the cathode. The optimization of different experimental parameters like initial ion concentration, current density, pH, temperature, etc., on the removal efficiency of manganese was carried out. The maximum removal efficiency of 97.55 % was achieved at a current density of 0.08 A dm-2 and pH of 7.0. The Langmuir, Freundlich and Redlich Peterson isotherm models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The adsorption of manganese preferably followed the Langmuir adsorption isotherm. The adsorption kinetics was modelled by first- and second- order rate models and the adsorption kinetic studies showed that the adsorption of manganese was best described using the second-order kinetic model. Thermodynamic parameters indicate that the adsorption of manganese on hydrous titanium dioxide was feasible, spontaneous and exothermic.

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

Science.gov (United States)

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.

Silicon-Doped Titanium Dioxide Nanotubes Promoted Bone Formation on Titanium Implants.

Science.gov (United States)

Zhao, Xijiang; Wang, Tao; Qian, Shi; Liu, Xuanyong; Sun, Junying; Li, Bin

2016-02-26

While titanium (Ti) implants have been extensively used in orthopaedic and dental applications, the intrinsic bioinertness of untreated Ti surface usually results in insufficient osseointegration irrespective of the excellent biocompatibility and mechanical properties of it. In this study, we prepared surface modified Ti substrates in which silicon (Si) was doped into the titanium dioxide (TiO₂) nanotubes on Ti surface using plasma immersion ion implantation (PIII) technology. Compared to TiO₂ nanotubes and Ti alone, Si-doped TiO₂ nanotubes significantly enhanced the expression of genes related to osteogenic differentiation, including Col-I, ALP, Runx2, OCN, and OPN, in mouse pre-osteoblastic MC3T3-E1 cells and deposition of mineral matrix. In vivo, the pull-out mechanical tests after two weeks of implantation in rat femur showed that Si-doped TiO₂ nanotubes improved implant fixation strength by 18% and 54% compared to TiO₂-NT and Ti implants, respectively. Together, findings from this study indicate that Si-doped TiO₂ nanotubes promoted the osteogenic differentiation of osteoblastic cells and improved bone-Ti integration. Therefore, they may have considerable potential for the bioactive surface modification of Ti implants.

NOx photocatalytic degradation on gypsum plates modified by TiO2-N,C photocatalysts

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Janus Magdalena

2015-09-01

Full Text Available In presented studies the photocatalytic decomposition of NOx on gypsum plates modified by TiO2-N,Cphotocatalysts were presented. The gypsum plates were obtained by addition of 10 or 20 wt.% of different types of titanium dioxide, such as: pure TiO2 and carbon and nitrogen co-modified TiO2 (TiO2-N,C to gypsum. TiO2-N,C photocatalysts were obtained by heating up the starting TiO2 (Grupa Azoty Zakłady Chemiczne Police S.A in the atmosphere of ammonia and carbon at the temperature: 100, 300 i 600ºC. Photocatalyst were characterized by FTIR/DRS, UVVis/DR, BET and XRD methods. Moreover the compressive strength tests of modified gypsum were also done. Photocatalytic activity of gypsum plates was done during NOx decomposition. The highest photocatalytic activity has gypsum with 20 wt.% addition of TiO2-N,C obtained at 300ºC.

Synthesis and Characterization of CNT/TiO2/ZnO Composites with High Photocatalytic Performance

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Yanzhen Huang

2018-04-01

Full Text Available Novel carbon nanotubes (CNTs/titanium dioxide (TiO2/zinc oxide (ZnO composites have been successfully synthesized via a two-step solution method using titanyl sulfate as the titanium precursor. Its structural performances were researched by various characterization methods, such as X-ray powder diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM and UV-vis diffuse reflectance spectroscopy (UV-vis DRS. The performance of the composites was tested by degrading rhodamine B (RhB under UV-vis illumination and found to strongly rely on the content of ZnO. The experimental results showed that the CNT/TiO2/ZnO-90 wt % expressed more outstanding photocatalytic performance compared to the corresponding binary composites and the CNT/TiO2/ZnO-85 wt %, CNT/TiO2/ZnO-95 wt % materials. The improved photocatalytic activity was attributed to synergistic effect of CNT, TiO2 and ZnO, in which ZnO can absorb photons to produce electrons and holes, whereas TiO2 and CNT can reduce the electron-hole recombination.

Photocytotoxicity in human dermal fibroblasts elicited by permanent makeup inks containing titanium dioxide.

Science.gov (United States)

Wamer, Wayne G; Yin, Jun-Jie

2011-01-01

Titanium dioxide (TiO2) is a pigment widely used in decorative tattoo and permanent makeup inks. However, little is known about the risks associated with its presence in these products. We have developed an in vitro assay to identify inks containing TiO2 that are cytotoxic and/or photocytotoxic. The presence of TiO2 in ten permanent makeup inks was established by X-ray fluorescence. Using X-ray diffraction, we found that seven inks contained predominately TiO2 (anatase), the more photocatalytically active crystalline form of TiO2. The remaining inks contained predominately TiO2 (rutile). To identify cytotoxic and/or photocytotoxic inks, human dermal fibroblasts were incubated for 18 h in media containing inks or pigments isolated from inks. Fibroblasts were then irradiated with 10 J/cm2 UVA radiation combined with 45 J/cm2 visible light for determining photocytotoxicity, or kept in the dark for determining cytotoxicity. Toxicity was assessed as inhibition of colony formation. No inks were cytotoxic. However eight inks, and the pigments isolated from these inks, were photocytotoxic. Using ESR, we found that most pigments from photocytotoxic inks generated hydroxyl radicals when photoexcited with UV radiation. Therefore, the possibility of photocytotoxicity should be considered when evaluating the safety of permanent makeup inks containing TiO2.

Electrochemical Properties of Transparent Conducting Films of Tantalum-Doped Titanium Dioxide

Czech Academy of Sciences Publication Activity Database

Krýsová, Hana; Mazzolini, P.; Casari, C. S.; Russo, V.; Li Bassi, A.; Kavan, Ladislav

2017-01-01

Roč. 232, APR 2017 (2017), s. 44-53 ISSN 0013-4686 R&D Projects: GA ČR GA13-07724S Institutional support: RVO:61388955 Keywords : titanium dioxide * tantalum doping * electrochemistry Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 4.798, year: 2016

Electrospray deposition of titanium dioxide (TiO{sub 2}) nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Halimi, Siti Umairah, E-mail: fitrah@salam.uitm.edu.my; Bakar, Noor Fitrah Abu, E-mail: fitrah@salam.uitm.edu.my; Ismail, Siti Norazian, E-mail: fitrah@salam.uitm.edu.my; Hashib, Syafiza Abd, E-mail: fitrah@salam.uitm.edu.my [Faculty of Chemical Engineering, UniversitiTeknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Naim, M. Nazli [Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia (UPM), 43400 Serdang, Selangor (Malaysia)

2014-02-24

Deposition of titanium dioxide (TiO{sub 2}) nanoparticles was conducted by using eletrospray method. 0.05wt% of titanium dioxide suspension was prepared and characterized by using Malvern Zetasizer prior to the experiment. From Zetasizer results, stable suspension condition was obtained which is at pH 2 with zeta potential value of ±29.0 mV. In this electrospraying, the suspension was pumped at flowrate of 5 ml/hr by using syringe pump. The input voltage of 2.1 kV was applied at the nozzle tip and counter electrode. Electrosprayed particles were collected on the grounded aluminium plate substrate which was placed at 10–20 cm from counter electrode. Particles were then characterized using FESEM and average size of electrosprayed particles obtained. Initial droplet size was calculated by scaling law and compared with FE-SEM results in order to prove droplet fission occur during electrospray. Due to the results obtained, as the working distance increase from 10–20 cm the deposited TiO{sub 2} droplet size decrease from 247–116 nm to show droplet fission occur during the experiment.

Effects of titanium dioxide nanoparticles on soil microbial communities and wheat biomass

NARCIS (Netherlands)

Moll, Janine; Klingenfuss, Florian; Widmer, Franco; Gogos, Alexander; Bucheli, Thomas D.; Hartmann, Martin; van der Heijden, Marcel G.A.

2017-01-01

Titanium dioxide nanoparticles (TiO2 NPs) are the most produced NPs worldwide and have great potential to be utilized in agriculture as additives for plant protection products. However, concerns have been raised that some NPs may negatively affect crops and soil microbial communities, including

Removal of the hazardous dye-Tartrazine by photodegradation on titanium dioxide surface

International Nuclear Information System (INIS)

Gupta, Vinod K.; Jain, Rajeev; Nayak, Arunima; Agarwal, Shilpi; Shrivastava, Meenakshi

2011-01-01

The removal of the dye-tartrazine by photodegradation has been investigated using titanium dioxide surface as photocatalyst under UV light. The process was carried out at different pH, catalyst dose, dye concentration and effects of the electron acceptor H 2 O 2 . It was found that under the influence of TiO 2 as catalyst, the colored solution of the dye became colorless and the process followed a pseudo first order kinetics. The optimum conditions for the degradation of dye were 6 x 10 -5 M dye concentration, pH of 11, and 0.18 mg/L of catalyst dose. In order to evaluate the effect of electron acceptor, the effect of H 2 O 2 on the degradation process was also monitored and it was found that the hydroxyl radical formation and retardation of electron-hole recombination took place simultaneously. The adsorption studies of tartrazine at various dose of TiO 2 followed the Langmuir isotherm trend. In order to determine the quality of waste water, Chemical Oxygen Demand (COD) measurements were carried out both before and after the treatment and a significant decrease in the values was observed, implying good potential of this technique to remove tartrazine dye from aqueous solutions. Research highlights: →Degradation efficiency increases with increase in catalyst concentration. →Adsorption of tartrazine on TiO 2 followed the Langmuir isotherm. →The photocatalytic kinetics follows first order.

Removal of the hazardous dye-Tartrazine by photodegradation on titanium dioxide surface

Energy Technology Data Exchange (ETDEWEB)

Gupta, Vinod K., E-mail: vinodfcy@gmail.com [Indian Institute of Technology Roorkee, Department of Chemistry, Roorkee, 247667 (India); King Fahd University of Petroleum and Minerals, Chemistry Department, Dhahran (Saudi Arabia); Jain, Rajeev [Jiwaji University, Department of Environmental Chemistry, Gwalior-474011 (India); Nayak, Arunima [Indian Institute of Technology Roorkee, Department of Chemistry, Roorkee, 247667 (India); Agarwal, Shilpi; Shrivastava, Meenakshi [Jiwaji University, Department of Environmental Chemistry, Gwalior-474011 (India)

2011-07-20

The removal of the dye-tartrazine by photodegradation has been investigated using titanium dioxide surface as photocatalyst under UV light. The process was carried out at different pH, catalyst dose, dye concentration and effects of the electron acceptor H{sub 2}O{sub 2}. It was found that under the influence of TiO{sub 2} as catalyst, the colored solution of the dye became colorless and the process followed a pseudo first order kinetics. The optimum conditions for the degradation of dye were 6 x 10{sup -5} M dye concentration, pH of 11, and 0.18 mg/L of catalyst dose. In order to evaluate the effect of electron acceptor, the effect of H{sub 2}O{sub 2} on the degradation process was also monitored and it was found that the hydroxyl radical formation and retardation of electron-hole recombination took place simultaneously. The adsorption studies of tartrazine at various dose of TiO{sub 2} followed the Langmuir isotherm trend. In order to determine the quality of waste water, Chemical Oxygen Demand (COD) measurements were carried out both before and after the treatment and a significant decrease in the values was observed, implying good potential of this technique to remove tartrazine dye from aqueous solutions. Research highlights: {yields}Degradation efficiency increases with increase in catalyst concentration. {yields}Adsorption of tartrazine on TiO{sub 2} followed the Langmuir isotherm. {yields}The photocatalytic kinetics follows first order.

HIGH-QUALITY ORNAMENTAL FINE CONCRETES MODIFIED BY NANOPARTICLES OF TITANIUM DIOXIDE

Directory of Open Access Journals (Sweden)

Bazhenov Yuriy Mikhaylovich

2012-10-01

Full Text Available Ultrasonic method of generation of a stable suspension of nano-particles of titanium dioxide and the strengthening properties of the ornamental fine concrete that contains cement binders with a nano-dispersed additive constitute the subject of the research covered by the authors. Nanoparticles react with the basic chemical elements that compose the concrete and act as crystallization centres. Therefore, the concrete porosity is reduced, while physical and technology-related properties of the ornamental fine concrete are improved. The authors have proven that the application of the nano-dispersed additive that contains titanium dioxide influences the processes of the structure formation in respect of fine ornamental concretes and improves the strength, as well as the water and cold resistance of fine concretes. The improvement is attributed to the dense concrete structure and strong adhesion between cement grains and between the cement and the aggregate. This conclusion is based on the data obtained through the employment of an electronic microscope used to identify the porosity of fine concretes.

Influence of zirconium doping on the activities of zirconium and iodine co-doped titanium dioxide in the decolorization of methyl orange under visible light irradiation

International Nuclear Information System (INIS)

Song Shuang; Hong Fangyue; He Zhiqiao; Wang Hongyu; Xu Xianghong; Chen Jianmeng

2011-01-01

Zirconium and iodine co-doped titanium dioxide (Zr-I-TiO 2 ) was prepared by the hydrolysis of tetrabutyl titanate, premixed with zirconium nitrate in an iodic acid aqueous solution, followed by calcination in air. The structure and properties of the resultant catalyst powders were characterized by X-ray diffraction, the Brunauer-Emmett-Teller method, X-ray photoelectron spectroscopy, transmission electron microscopy, and UV-vis absorption spectroscopy. The catalytic activity of the catalyst was evaluated by monitoring the photocatalytic decolorization of methyl orange under visible light irradiation. The results showed that the activities of Zr-I-TiO 2 catalysts were higher than that of TiO 2 doped with iodine alone (I-TiO 2 ), and the optimal doping concentration in the Zr-I-TiO 2 calcined at 400 deg. C was determined to be about 0.05 (molar ratio of Zr:Ti). In addition, the photocatalytic activity of Zr-I-TiO 2 calcined at 400 deg. C was found to be significantly higher than that calcined at 500 or 600 deg. C. Based on the physico-chemical characterization, we concluded that the role of zirconium on the I-TiO 2 surface is to increase the number of reactive sites by generating a small crystal size and large surface area. The inhibition of electron-hole pair recombination, by trapping photo-generated electrons with Zr 4+ , did not contribute markedly to the improved photocatalytic activity of Zr-I-TiO 2 .

Stable Photocatalytic Paints Prepared from Hybrid Core-Shell Fluorinated/Acrylic/TiO2 Waterborne Dispersions

Directory of Open Access Journals (Sweden)

Audrey Bonnefond

2016-10-01

Full Text Available The contamination of air and water is one of the major concerns towards the development of a sustainable world in the 21st century. In this context many efforts are devoted to the design of photocatalytic paints able to degrade chemical and biological impurities present in air and water. In this work, the photocatalytic activity of hybrid films formed from the blends of pure acrylic or core/shell fluorinated/acrylic waterborne dispersions and photocatalytic titanium dioxide (TiO2 nanoparticle dispersions was first assessed. The films show photocatalytic activity (inactivation of the Escherichia coli bacteria under UV irradiation at the substrate-film interface, but very reduced activity in the air-film interface due to the substantially lower amount of the TiO2 nanoparticles in the vicinity of this interface. In a second step, the fluorinated/(methacrylic core-shell hybrid dispersions were used as binders in the formulation of waterborne photocatalytic paints and the stability of the paints, in terms of gloss retain and color change, was assessed during 5000 hours of accelerated weathering tests (QUV-B. Although a decrease in gloss retention and increased color change occurs during the first 1000 hours of exposure, no further change of these properties takes place, which is an excellent indication of stable photocatalytic paints.

Photocatalytic Oxidation of NO over Composites of Titanium Dioxide and Zeolite ZSM-5

Directory of Open Access Journals (Sweden)

Akram Tawari

2016-02-01

Full Text Available Composites of TiO2 (Hombikat, P25, sol-gel synthesis and zeolite ZSM-5 (nSi/nAl = 55 with mass fractions from 25/75 to 75/25 were prepared by mechanical mixing, solid-state dispersion and sol-gel synthesis. Characterization of the composites by X-ray diffraction (XRD, N2-sorption, scanning electron microscopy (SEM, and UV-Vis spectroscopy show that mechanical mixing and solid-state dispersion lead to comparable textural properties of the composites. A homogeneous distribution and intimate contact of small TiO2 particles on the crystal surface of zeolite ZSM-5 were achieved by sol-gel synthesis. The composites were studied in the photocatalytic oxidation (PCO of NO in a flatbed reactor under continuous flow according to ISO 22197-1. The highest NO conversion of 41% at an NO2 selectivity as low as 19% stable for 24 h on-stream was reached over the TiO2/ZSM-5 composite from sol-gel synthesis with equal amounts of the two components after calcination at 523 K. The higher activity and stability for complete NO oxidation than for pure TiO2 from sol-gel synthesis, Hombikat, or P25 is attributed to the adsorptive properties of the zeolite ZSM-5 in the composite catalyst. Increasing the calcination temperature up to 823 K leads to larger TiO2 particles and a lower photocatalytic activity.

Chances and limitations of nanosized titanium dioxide practical application in view of its physicochemical properties

Science.gov (United States)

Bogdan, Janusz; Jackowska-Tracz, Agnieszka; Zarzyńska, Joanna; Pławińska-Czarnak, Joanna

2015-02-01

Nanotechnology is a field of science that is nowadays developing in a dynamic way. It seems to offer almost endless opportunities of contribution to many areas of economy and human activity, in general. Thanks to nanotechnology, the so-called nanomaterials can be designed. They present structurally altered materials, with their physical, chemical and biological properties entirely differing from properties of the same materials manufactured in microtechnology. Nanotechnology creates a unique opportunity to modify the matter at the level of atoms and particles. Therefore, it has become possible to obtain items displaying new, useful properties, i.e. self-disinfecting and self-cleaning surfaces. Those surfaces are usually covered by a thin layer of a photocatalyst. The role of the photocatalyst is most of the time performed by the nanosized titanium dioxide (nano-TiO2). Excitation of nano-TiO2 by ultraviolet radiation initiates advanced oxidation processes and reactions leading to the creation of oxygen vacancies that bind water particles. As a result, photocatalytic surfaces are given new properties. Those properties can then be applied in a variety of disciplines, such as medicine, food hygiene, environmental protection or building industry. Practically, the applications include inactivation of microorganisms, degradation of toxins, removing pollutants from buildings and manufacturing of fog-free windows or mirrors.

Preparation and Characterization of Surface Photocatalytic Activity with NiO/TiO2 Nanocomposite Structure

OpenAIRE

Chen, Jian-Zhi; Chen, Tai-Hong; Lai, Li-Wen; Li, Pei-Yu; Liu, Hua-Wen; Hong, Yi-You; Liu, Day-Shan

2015-01-01

This study achieved a nanocomposite structure of nickel oxide (NiO)/titanium dioxide (TiO2) heterojunction on a TiO2 film surface. The photocatalytic activity of this structure evaluated by decomposing methylene blue (MB) solution was strongly correlated to the conductive behavior of the NiO film. A p-type NiO film of high concentration in contact with the native n-type TiO2 film, which resulted in a strong inner electrical field to effectively separate the photogenerated electron-hole pairs,...

A simple UV-ozone surface treatment to enhance photocatalytic performance of TiO 2 loaded polymer nanofiber membranes

KAUST Repository

Dilpazir, S.

2016-01-29

Homogeneously dispersed titanium dioxide loaded polyacrylonitrile nanofiber membranes with increased active mass loading, Ti3+ surface defects and hydrophilicity were fabricated by combining electrospinning and UV-ozone surface treatment. The photocatalytic activity improved by a factor of ∼2 and the kinetics of photodegradation switched from pseudo-first order to pseudo-second order with increasing TiO2 content with a maximum rate constant of 20.7 h-1. © The Royal Society of Chemistry 2016.

Effects of titanium dioxide nanoparticles on red clover and its rhizobial symbiont

NARCIS (Netherlands)

Moll, Janine; Okupnik, Annette; Gogos, Alexander; Knauer, Katja; Bucheli, Thomas D.; Van Der Heijden, Marcel G A; Widmer, Franco

2016-01-01

Titanium dioxide nanoparticles (TiO2 NPs) are in consideration to be used in plant protection products. Before these products can be placed on the market, ecotoxicological tests have to be performed. In this study, the nitrogen fixing bacterium Rhizobium trifolii and red clover were exposed to two

The decisive effect of interface states on the photocatalytic activity of the silver(I) oxide/titanium dioxide heterojunction.

Science.gov (United States)

Lei, Yanqiang; Lu, Xiaoqing

2017-04-15

A one-step hydrothermal method was adopted to synthesize the Ag 2 O/TiO 2 nanoheterojunction. Its photocatalytic activity was evaluated by degrading methylene blue (MB) aqueous solution under UV and visible light. The MB degradation results showed that the Ag 2 O/TiO 2 nanoheterojunction enhances the photocatalytic activity under UV irradiation rather than visible light. X-ray photoelectron spectroscopy (XPS) was performed to detect the electronic structure at the interface of Ag 2 O and TiO 2 . The XPS results confirmed that the electronic band structure of the nanoheterojunction was determined by the interface states between the Ag 2 O and TiO 2 interface. Thus, the photocatalytic enhancement mechanism can be ascribed to the creation of an additional potential barrier in the conduction band between Ag 2 O and TiO 2 , which facilitates the transport of holes from TiO 2 to Ag 2 O but inhibits the flow of electrons in the reverse direction unless sufficient potential energy is provided to overcome the additional barrier. Our results have provided a new insight on the role of interface states between the p-n nanojunction in the photocatalytic activity. Copyright © 2017 Elsevier Inc. All rights reserved.

FY1995 studies on surface structures and mechanism of photocatalytic action of semiconductor oxides; 1995 nendo handotai hikari shokubai no hyomen kozo seigyo to sayo kiko kaimei ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

Development of the semiconductor photocatalyst such as titanium dioxide is important for photo-energy conversion and purification of the environment. We make clear that the mechanism of the photocatalysis using a spectroscopic or physico-chemical methods, and we developed the new photocatalyst with the control of the surface area, porosity, infinitesimal content, and surface modification of the catalyst surface. Titanium dioxide thin film photocatalysts were prepared by the dip coating method. Surface structure of the thin film was formed by the aggregated TiO{sub 2} anatase particle, its size was around 5 nm. This thin films effectively oxidazed NO, its photocatalytic activity is higher than that of commercial photocatalyst. Metal oxide anchored TiO{sub 2} photocatalysts (RuO{sub 2}/TiO{sub 2}) were prepared by the co-precipitation method. Effective charge separation of the RuO{sub 2}/TiO{sub 2} were confirmed by the measurement of ESR. The RuO{sub 2}/TiO{sub 2} photocatalyst successfully reduced CO{sub 2} and preserved its activity for much longer period than metal loaded catalyst. Hybrid photofunctionalized material was prepared by anchoring porphyrin moieties on the titanium dioxide surface. The relative quantum yield of electron transfer from porphyrin to the titanium dioxide conduction band has been markedly increased by water treatment of quanternized porphyrin-titanium dioxide covalently linked systems owing to removal of adsorbed porphyrin domains. (NEDO)

Solar photocatalytic cleaning of polluted water. Solare Reinigung verschmutzter Waesser mittels Photokatalyse

Energy Technology Data Exchange (ETDEWEB)

Bockelmann, D

1994-01-01

Alternatively to biological, physical and chemical methods of waste water cleaning, photocatalysis can be employed. In this residue-free method, titanium dioxide particles are brought into contact with polluted water as photocatalysts. Under UV irradiation at wave-lengths below 400 nm, change carriers are generated in the semiconductor particles that act so intensely oxidizing as to completely degrade almost all organic pollutants in waste water. In this process, the ultra-violet part of the solar spectrum can be harnessed to generate oxidation equivalents. Thus, solar photocatalytic waste water cleaning is excellently suited for developing countries. (BWI)

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

Science.gov (United States)

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.

Effects of Nano-Titanium Dioxide on Freshwater Algal Population Dynamics

Science.gov (United States)

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

Photocatalytic degradation of organic contaminants under solar light using carbon dot/titanium dioxide nanohybrid, obtained through a facile approach

Energy Technology Data Exchange (ETDEWEB)

Hazarika, Deepshikha; Karak, Niranjan, E-mail: karakniranjan@gmail.com

2016-07-15

Highlights: • Nitrogen containing carbon dot and carbon dot/TiO{sub 2} nanohybrid (CD@TiO{sub 2}) are synthesized without any additional doping of passivating agent. • The photocatalytic efficacy of CD@TiO{sub 2} is found to be the best as compared to the bare TiO{sub 2}, CD and nanohybrid of TiO{sub 2} in presence of carbon dot. • Up-conversion luminescence of CD promotes the degradation activity of synthesized CD@TiO{sub 2} under visible light. • The hazardous contaminants like phenol, benzene and pesticide are efficiently degraded by CD@TiO{sub 2} under normal sunlight. - Abstract: In the present study, a novel, simple and green method was developed to synthesize highly luminescent nitrogen containing carbon dot (CD) using carbon resources like bio-based citric acid and glycerol in the presence of cost free cow urine. The as-synthesized CD showed exciting wavelength dependent down- and up-conversion flourescence properties. To utilize the advantage of up-conversion flourescence, a nanohybrid (CD@TiO{sub 2}) was synthesized from the above carbon resources and titanium butoxide through a facile one pot single step hydrothermal protocol. Nanomaterials like bare TiO{sub 2} and nanohybrid of TiO{sub 2} in presence of CD (CD/TiO{sub 2}) were also synthesized for comparison purpose. The optical properties and structural characteristics of the prepared CD, bare TiO{sub 2}, CD@TiO{sub 2} and CD/TiO{sub 2} were examined by Fourier transform infrared (FTIR), UV–vis and fluorescence spectroscopic, scanning electron microscopic (SEM), transmission electron microscopic (TEM) and X-ray diffraction (XRD) studies. The elemental compositions of bare CD and CD@TiO{sub 2} nanohybrid were obtained from EDX analyses. The poor crystalline nature and narrow distribution of spherical CD and anatase form of TiO{sub 2} were confirmed from XRD and TEM studies. Amongst the studied nanomaterials, CD@TiO{sub 2} exhibited the most promising photocatalytic degradation of organic

Preparation and integration of nanostructured titanium dioxide

KAUST Repository

Zeng, Hua Chun

2011-10-01

Titanium dioxide (TiO2) is a chemically stable nontoxic transition-metal oxide associated with a wide range of existing chemical engineering processes. In this short review, recent research endeavors in preparation and integration of nanostructured TiO2 materials system will be featured and discussed for their potential new applications. Because material development always plays pivotal roles in the progress of a particular engineering discipline, the reviewed subjects will provide useful information to stimulate nanoscale research of chemical engineering, linking established fundamentals with practical applications. Some critical issues and challenges regarding further development of this important functional material for nanotechnology will also be addressed. © 2011 Elsevier Ltd. All rights reserved.

Titanium di-oxide films using a less hygroscopic colloidal precursor

Energy Technology Data Exchange (ETDEWEB)

Vandana,, E-mail: vandana1@nplindia.org; Batra, Neha; Kumar, Praveen; Sharma, Pooja; Singh, P.K., E-mail: pksingh@nplindia.org

2014-04-01

We report the study of titanium dioxide films (TiO{sub 2}) using titanium di-isopropoxyl di-2ethyl hexanoate Ti(OC{sub 3}H{sub 7}){sub 2} (C{sub 7}H{sub 15}COO){sub 2} colloidal precursor. This compound is less hygroscopic in nature and easy to use with processes like spin or dip coating. Thin films of TiO{sub 2} are made on silicon substrates and their structural and optical properties are studied. The effect of Ti content in the precursor, sintering temperature and its duration on film thickness and refractive index are investigated. Refractive index shows an increasing trend with the rise in the sintering temperature but remains unchanged with the time. The film thickness decreases with both sintering temperature and time and increases with Ti content in the precursor. Reflectivity measurements show marked reduction in the reflection losses compared to bare silicon surface wherein the film thickness is altered by spin speed. XRD results show anatase phase in the samples sintered at lower temperature (<680 °C), however, a mix of anatase, brookite and rutile phases is seen above this temperature. In the samples sintered above 1100 °C, rutile phase is dominant. These results are supported by the X-ray photoelectron spectroscopy. Atomic force microscopy reveals larger grain size at higher sintering temperature. The titanium dioxide films of desirable thickness and refractive index could be used as an antireflection coating on solar cells. - Highlights: • TiO{sub 2} films are made using titanium di-isopropoxyl di-2ethyl hexanoate precursor. • Effect of Ti content in the precursor, sintering temperature and time is studied. • Refractive index (μ) increases with sintering temperature but is independent of time. • Films of desired thickness and μ could be used as an antireflection coating. • XRD results show that rutile phase dominates in samples sintered above 1100 °C.

Opportunities in the electrowinning of molten titanium from titanium dioxide

CSIR Research Space (South Africa)

Van Vuuren, DS

2005-10-01

Full Text Available used, the following forms of titanium are produced: titanium sponge, sintered electrode sponge, powder, molten titanium, electroplated titanium, hydride powder, and vapor-phase depos- ited titanium. Comparing the economics of alter- native...-up for producing titanium via the Kroll process is approximately as follows: ilmenite ($0.27/kg titanium sponge); titanium slag ($0.75/kg titanium sponge); TiCl4 ($3.09/kg titanium sponge); titanium sponge raw materials costs ($5.50/kg titanium sponge); total...

Multiple-diffusion flame synthesis of pure anatase and carbon-coated titanium dioxide nanoparticles

KAUST Repository

Memon, Nasir; Anjum, Dalaver H.; Chung, Suk-Ho

2013-01-01

A multi-element diffusion flame burner (MEDB) is useful in the study of flame synthesis of nanomaterials. Here, the growth of pure anatase and carbon-coated titanium dioxide (TiO2) using an MEDB is demonstrated. Hydrogen (H2), oxygen (O2), and argon

Food contact surfaces coated with nitrogen-doped titanium dioxide: effect on Listeria monocytogenes survival under different light sources

International Nuclear Information System (INIS)

Rodrigues, D.; Teixeira, P.; Tavares, C.J.; Azeredo, J.

2013-01-01

Improvement of food safety is a very important issue, and is on the basis of production and application of new/modified food contact surfaces. Titanium dioxide (TiO 2 ) and, more recently, nitrogen-doped titanium dioxide (N-TiO 2 ) coatings are among the possible forms to enhance food contact surfaces performance in terms of higher hygiene and easier sanitation. In this context, the present work aimed at evaluating the bactericidal activity of an N-TiO 2 coating on glass and stainless steel under two different sources of visible light – fluorescent and incandescent – and ultraviolet (UV) irradiation. Listeria monocytogenes was chosen as representative of major foodborne pathogens and its survival was tested on N-TiO 2 coated coupons. In terms of survival percentage, good results were obtained after exposure of coated surfaces to all light types since, apart from the value obtained after exposing glass to fluorescent light (56.3%), survival rates were always below 50%. However, no effective disinfection was obtained, given that for a disinfectant or sanitizing agent to be claimed as effective it needs to be able to promote at least a 3-log reduction of the microbial load, which was not observed for any of the experimental conditions assessed. Even so, UV irradiation was the most successful on eliminating cells on coated surfaces, since the amount of bacteria was reduced to 1.49 × 10 6 CFU/ml on glass and 2.37 × 10 7 on stainless steel. In contrast, both visible light sources had only slightly decreased the amount of viable cells, which remained in the range of 8 log CFU/ml. Hence, although some bactericidal effect was accomplished under visible light, UV was the most effective light source on promoting photocatalytic reactions on N-TiO 2 coated coupons and none of the experimental conditions have reached a satisfactory disinfection level. Thus, this surface coating needs further research and improvement in order to become truly effective against foodborne

Food contact surfaces coated with nitrogen-doped titanium dioxide: effect on Listeria monocytogenes survival under different light sources

Science.gov (United States)

Rodrigues, D.; Teixeira, P.; Tavares, C. J.; Azeredo, J.

2013-04-01

Improvement of food safety is a very important issue, and is on the basis of production and application of new/modified food contact surfaces. Titanium dioxide (TiO2) and, more recently, nitrogen-doped titanium dioxide (N-TiO2) coatings are among the possible forms to enhance food contact surfaces performance in terms of higher hygiene and easier sanitation. In this context, the present work aimed at evaluating the bactericidal activity of an N-TiO2 coating on glass and stainless steel under two different sources of visible light - fluorescent and incandescent - and ultraviolet (UV) irradiation. Listeria monocytogenes was chosen as representative of major foodborne pathogens and its survival was tested on N-TiO2 coated coupons. In terms of survival percentage, good results were obtained after exposure of coated surfaces to all light types since, apart from the value obtained after exposing glass to fluorescent light (56.3%), survival rates were always below 50%. However, no effective disinfection was obtained, given that for a disinfectant or sanitizing agent to be claimed as effective it needs to be able to promote at least a 3-log reduction of the microbial load, which was not observed for any of the experimental conditions assessed. Even so, UV irradiation was the most successful on eliminating cells on coated surfaces, since the amount of bacteria was reduced to 1.49 × 106 CFU/ml on glass and 2.37 × 107 on stainless steel. In contrast, both visible light sources had only slightly decreased the amount of viable cells, which remained in the range of 8 log CFU/ml. Hence, although some bactericidal effect was accomplished under visible light, UV was the most effective light source on promoting photocatalytic reactions on N-TiO2 coated coupons and none of the experimental conditions have reached a satisfactory disinfection level. Thus, this surface coating needs further research and improvement in order to become truly effective against foodborne pathogens and

Nanocomposites based on titanium dioxide and polythiophene: structure and properties

Czech Academy of Sciences Publication Activity Database

Vu, Q. T.; Pavlík, Martin; Hebestreit, N.; Rammelt, U.; Plieth, W.; Pfleger, Jiří

2005-01-01

Roč. 65, 1-2 (2005), s. 69-77 ISSN 1381-5148. [International Conference on Polymers and Organic Chemistry /11./. Prague, 18.06.2004-23.06.2004] R&D Projects: GA AV ČR IAA4050406 Grant - others:European Graduate School: Advanced Polymeric Materials(XE) IGK720 Institutional research plan: CEZ:AV0Z40500505 Keywords : polythiophene * titanium dioxide * nanocomposites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.565, year: 2005

Photocatalytic, antifogging mirror

International Nuclear Information System (INIS)

Takagi, K.; Makimoto, T.; Hiraiwa, H.; Negishi, T.

2001-01-01

This article is about the coating of thin titanium dioxide film by sputter deposition. When irradiated with solar light, thin titanium dioxide film exhibits high oxidizing power and provides sterilizing, cleaning, decomposing, and hydrophylic effects. This technique has already been used for coating building walls by the sol-gel method and by others and has been partly commercialized to make automotive sideview mirrors. There have been no practical applications of the sputter deposition method so far, but establishment of the coating method is expected because of its excellent properties of film production techniques such as film thickness uniformity, film quality durability, and freedom from environmental pollution. In this article we discuss the establishment of the method of evaluating the quality of thin titanium dioxide film, establishment of sputter-deposition conditions, and the results of observation by x-ray diffraction and atomic force microscopy of the thin film. It was found that titanium dioxide films, 200 nm or more in thickness, have the above mentioned performance and that sputter deposition allows the film to form without heating

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

Science.gov (United States)

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...

Photocatalytic activity of ferric oxide/titanium dioxide nanocomposite films on stainless steel fabricated by anodization and ion implantation

Science.gov (United States)

Zhan, Wei-ting; Ni, Hong-wei; Chen, Rong-sheng; Yue, Gao; Tai, Jun-kai; Wang, Zi-yang

2013-08-01

A simple surface treatment was used to develop photocatalytic activity for stainless steel. AISI 304 stainless steel specimens after anodization were implanted by Ti ions at an extracting voltage of 50 kV with an implantation dose of 3 × 1015 atoms·cm-2 and then annealed in air at 450°C for 2 h. The morphology was observed by scanning electron microscopy. The microstructure was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The photocatalytic degradation of methylene blue solution was carried out under ultraviolet light. The corrosion resistance of the stainless steel was evaluated in NaCl solution (3.5 wt%) by electrochemical polarization curves. It is found that the Ti ions depth profile resembles a Gaussian distribution in the implanted layer. The nanostructured Fe2O3/TiO2 composite film exhibits a remarkable enhancement in photocatalytic activity referenced to the mechanically polished specimen and anodized specimen. Meanwhile, the annealed Ti-implanted specimen remains good corrosion resistance.

Preparation and performance of photocatalytic TiO2 immobilized on palladium-doped carbon fibers

International Nuclear Information System (INIS)

Zhu Yaofeng; Fu Yaqin; Ni Qingqing

2011-01-01

Pd-modified carbon fibers (CFs) are obtained by a facile oxidation-reduction method and then dip-coated in a sol-gel of titanium dioxide (TiO 2 ) to form supported TiO 2 /Pd-CF photocatalysts. The morphology of the Pd-modified CFs and the amount Pd deposited are characterized by field emission scanning electron microscopy and atomic absorption spectrometry, respectively. X-ray diffraction is used to investigate the crystal structures of the TiO 2 photocatalyst. Acid orange II is used as a model contaminant to evaluate the photocatalytic properties of the photocatalyst under UV irradiation. TiO 2 /Pd-CF exhibits higher catalytic activity than TiO 2 /CF towards the degradation of acid orange II. Optimum photocatalytic performance and support properties are achieved when the Pd particle loading is about 10.8 mg/g.

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

Science.gov (United States)

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...

Relationship between wheat characteristics and nutrient digestibility in broilers: comparison between total collection and marker (titanium dioxide) technique.

Science.gov (United States)

Smeets, N; Nuyens, F; Van Campenhout, L; Delezie, E; Pannecoucque, J; Niewold, T

2015-07-01

Three wheat cultivars (Orpheus, Rustic, and Viscount) were used to formulate 3 test feeds (62.4% wheat) in a broiler digestibility trial. The diets were fed to male Ross 308 broiler chickens. The wheat cultivars mainly differed in their amount of non-starch polysaccharides ( NSP: ). The cultivar Orpheus was chosen to represent a high amount of NSP (102 g/kg DM), whereas the cultivars Rustic and Viscount represented low amounts of NSP (83.4 g/kg DM and 73.9 g/kg DM, respectively). Furthermore, the cultivars Orpheus and Viscount were feed quality wheat, whereas Rustic was a milling quality wheat. Nutrient digestibilities and AMEn contents of the diets were measured from 18 to 22-days-old by total excreta collection, or with the use of the indigestible marker titanium dioxide. In addition, the ileal viscosity was measured when the broilers were 25-days-old. Wheat cultivar affected N retention, DM digestibility, and AMEn. In general, the feed formulated with the high NSP wheat cultivar Orpheus resulted in the least favorable nutrient digestibilities and AMEn, whereas the results were better when the feed was formulated with the low NSP cultivars Viscount and Rustic. Feeding the Rustic cultivar caused the highest intestinal viscosity, although this was not reflected in the animal responses. Nutrient digestibilities and AMEn content of the diets were lower when calculated with the titanium dioxide marker than with the total excreta collection procedure. Moreover, the P-values of the effect of wheat cultivar on DM digestibility, N retention, crude fat digestibility and AMEn were lower with the use of the titanium dioxide marker. It can be concluded that wheat cultivar affected nutrient digestibility and AMEn, and that the observed differences were related to the amount of NSP. Furthermore, both the titanium dioxide marker and the total excreta collection methods showed the same trends despite the different values obtained. The titanium dioxide marker method was the

Electron microscopic investigation and elemental analysis of titanium dioxide in sun lotion.

Science.gov (United States)

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.

Production and Characterization of TiO2 Nanofilms for Hemocompatible and Photocatalytic Applications

Science.gov (United States)

Schvezov, C. E.; Vera, M. L.; Schuster, J. M.; Rosenberger, M. R.

2017-10-01

Titanium dioxide (TiO2) coatings are currently produced for hemocompatible and photocatalytic applications by using two techniques: sol-gel and anodic oxidation. In this review, the research advances on TiO2 nanofilms produced with these techniques are presented, with a focus on different aspects such as process parameters, morphology, roughness, crystal structure, adhesion, wear and erosion resistance, corrosion resistance, hemocompatibility, toxicity, plaque and bacterial adhesion, and heterogeneous photocatalysis of immobilized porous material. This review was presented at the 3rd Pan American Materials Congress at the 2017 TMS Annual Meeting and Exhibition in San Diego, California, USA.

Improvement in electrical characteristics of eco-friendly indium zinc oxide thin-film transistors by photocatalytic reaction.

Science.gov (United States)

Kang, Jun Ki; Park, Sung Pyo; Na, Jae Won; Lee, Jin Hyeok; Kim, Dongwoo; Kim, Hyun Jae

2018-05-11

Eco-friendly solution-processed oxide thin-film transistors (TFTs) were fabricated through photocatalytic reaction of titanium dioxide (PRT). The titanium dioxide (TiO 2 ) surface reacts with H 2 O under ultraviolet (UV) light irradiation and generates hydroxyl radicals (OH∙). These hydroxyl radicals accelerate the decomposition of large organic compounds such as 2-methoxyethanol (2ME; one of the representative solvents for solution-processed metal oxides), creating smaller organic molecular structures compared with 2ME. The decomposed small organic materials have low molar masses and low boiling points, which help improving electrical properties via diminishing defect sites in oxide channel layers and fabricating low temperature solution-processed oxide TFTs. As a result, the field-effect mobility improved from 4.29 to 10.24 cm 2 /V·s for IGZO TFTs and from 2.78 to 7.82 cm 2 /V·s for IZO TFTs, and the V th shift caused by positive bias stress (PBS) and negative bias illumination stress (NBIS) over 1,000 s under 5,700 lux decreased from 6.2 to 2.9 V and from 15.3 to 2.8 V, respectively. In theory, TiO 2 has a permanent photocatalytic reaction; as such, hydroxyl radicals are generated continuously under UV irradiation, improving the electrical characteristics of solution-processed IZO TFTs even after four iterations of TiO 2 recycling in this study. Thus, the PRT method provides an eco-friendly approach for high-performance solution-processed oxide TFTs.

Enhancing the photoresponse and photocatalytic properties of TiO2 by controllably tuning defects across {101} facets

Science.gov (United States)

Wan, Piaopiao; Hood, Zachary D.; Adhikari, Shiba P.; Xu, Yunfan; Yang, Shize; Wu, Sujuan

2018-03-01

Introducing defects into semiconductors with well-controlled exposed facets offers an effective route for the development of photocatalytic materials with greatly improved properties. Here, we report a facile ethylene glycol reduction procedure to make anatase titanium dioxide (TiO2) with different concentrations of exposed {001} and {101} facets, leading to different surficial defects. TiO2 with increased concentrations of {101} facets shows a 5-fold improvement in photocurrent generation as well as improved photocatalytic activity towards water splitting under visible light irradiation. The improved activity is ascribed to the oxygen vacancies as well as the variable surface chemical states, which collectively induce a slower recombination rate of photo-induced electron-hole pairs. This work also highlights a feasible strategy to obtain the defective TiO2 and explore the synergistic effect of surface defects and different concentrations of exposed {001} and {101} facets for photocurrent and photocatalytic properties under visible light irradiation.

Laboratory Study on the Fatigue Resistance of Asphaltic Concrete Containing Titanium Dioxide

Directory of Open Access Journals (Sweden)

Buhari Rosnawati

2018-01-01

Full Text Available 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.

Laboratory Study on the Fatigue Resistance of Asphaltic Concrete Containing Titanium Dioxide

Science.gov (United States)

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.

Effect of different processes and Ti/Zn molar ratios on the structure, morphology, and enhanced photoelectrochemical and photocatalytic performance of Ti3+ self-doped titanium-zinc hybrid oxides

Science.gov (United States)

Fu, Rongrong; Wang, Qingyao; Gao, Shanmin; Wang, Zeyan; Huang, Baibiao; Dai, Ying; Lu, Jun

2015-07-01

Ti3+ self-doped titanium-zinc hybrid oxides with different phase compositions and morphologies were successfully synthesized using Zn powder as the reductant and Zn source by a chemical-reduction precipitation method with subsequent thermal treatment. The fabricated Ti3+ self-doped TiO2(A)/TiO2(R), TiO2(A)/TiO2(R)/ZnTiO3, and TiO2(A)/ZnO heterojunctions were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The effects of various Ti/Zn molar ratios and preparation processes on the structural, morphological, optical, photocurrent and photocatalytic properties of the resultant samples were investigated systematically. Results reveal that Ti3+ self-doping enhances the photoabsorption capability of titanium-zinc hybrid oxides in the visible-light region. Moreover, different processes and Ti/Zn molar ratios play great influences on the structure, morphology, optical, photocurrent and photocatalytic properties of the final products. Ti3+ self-doped titanium-zinc hybrid oxides exhibit excellent photocurrent and photocatalytic activity than pure TiO2 and ZnTiO3 under visible-light irradiation (λ ≥ 400 nm). The most active Ti3+ self-doped titanium-zinc hybrid oxides photoanode presents significantly improved water splitting performance. The synergistic effect between the Ti3+ self-doped and heterojunctions is responsible for the enhanced performance of these materials.

Photoluminescence and hydrogen gas-sensing properties of titanium dioxide nanostructures synthesized by hydrothermal treatments

CSIR Research Space (South Africa)

Sikhwivhilu, LM

2012-03-01

Full Text Available Titanium dioxide (TiO2) nanostructures were synthesized by microwave-assisted and conventionally heated hydrothermal treatment of TiO2 powder. The tubular structures were converted to a rodlike shape by sintering the samples at various temperatures...

Acute Toxicity of Intravenously Administered Titanium Dioxide Nanoparticles in Mice

OpenAIRE

Xu, Jiaying; Shi, Hongbo; Ruth, Magaye; Yu, Hongsheng; Lazar, Lissy; Zou, Baobo; Yang, Cui; Wu, Aiguo; Zhao, Jinshun

2013-01-01

BACKGROUND: With a wide range of applications, titanium dioxide (TiO₂) nanoparticles (NPs) are manufactured worldwide in large quantities. Recently, in the field of nanomedicine, intravenous injection of TiO₂ nanoparticulate carriers directly into the bloodstream has raised public concerns on their toxicity to humans. METHODS: In this study, mice were injected intravenously with a single dose of TiO₂ NPs at varying dose levels (0, 140, 300, 645, or 1387 mg/kg). Animal mortality, blood biochem...

Titanium dioxide thin films for high temperature gas sensors

Energy Technology Data Exchange (ETDEWEB)

Seeley, Zachary Mark; Bandyopadhyay, Amit; Bose, Susmita, E-mail: sbose@wsu.ed

2010-10-29

Titanium dioxide (TiO{sub 2}) thin film gas sensors were fabricated via the sol-gel method from a starting solution of titanium isopropoxide dissolved in methoxyethanol. Spin coating was used to deposit the sol on electroded aluminum oxide (Al{sub 2}O{sub 3}) substrates forming a film 1 {mu}m thick. The influence of crystallization temperature and operating temperature on crystalline phase, grain size, electronic conduction activation energy, and gas sensing response toward carbon monoxide (CO) and methane (CH{sub 4}) was studied. Pure anatase phase was found with crystallization temperatures up to 800 {sup o}C, however, rutile began to form by 900 {sup o}C. Grain size increased with increasing calcination temperature. Activation energy was dependent on crystallite size and phase. Sensing response toward CO and CH{sub 4} was dependent on both calcination and operating temperatures. Films crystallized at 650 {sup o}C and operated at 450 {sup o}C showed the best selectivity toward CO.

Relationship between Photocatalytic Activity and Ti{sup 3+} Defects in Acid-Leached Titanium Dioxide / Hydroxyapatite Composite

Energy Technology Data Exchange (ETDEWEB)

Ono, Y; Rachi, T; Okuda, T; Yokouchi, M; Kamimoto, Y [Mechanical and Material Engineering Division, Kanagawa Industrial Technology Center, 705-1 Shimo-imaizumi, Ebina, Kanagawa 243-0435 (Japan); Nakajima, A [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Okada, K, E-mail: ono-y@kanagawa-iri.go.jp [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuda, Midori-ku, Yokohama 226-8503 (Japan)

2011-10-29

Effect of Ti{sup 3+} defect density on the photocatalytic activity was investigated using electron spin resonance (ESR) spectroscopy under UV irradiation at 103K. The Ti{sup 3+} signal intensity decreased with increasing heating temperature for the TiO{sub 2} powders prepared by hydroxyapatite (HAp) precipitation, heating and acid leaching process. The Ti{sup 3+} defect density of the TiO{sub 2} powder heat-treated at 700 deg. C was found to be about half that of the starting material, P25, without anatase-to-rutile phase transformation based on the results of X-ray diffraction. The photocatalytic activity of the TiO{sub 2} powder determined from the change of methylene blue concentration under UV irradiation became higher with decreasing of the Ti{sup 3+} defects without a significant change in the anatase ratio and specific surface area during the heat treatment.

Reducing the pollutant load of olive mill wastewater by photocatalytic membranes and monitoring the process using both tyrosinase biosensor and COD test

Science.gov (United States)

Martini, Elisabetta; Tomassetti, Mauro; Campanella, Luigi; Fortuna, Antonio

2013-12-01

Photocatalytic technique had already been employed in the treatment of olive mill wastewater (OMW) using the photocatalysis in suspension. The coupling of photocatalytic and membrane techniques should result in a very powerful process bringing great innovation to OMW depollution. Despite the potential advantages using these hybrid photoreactors, research on the combined use of photocatalysis and membranes has so far not been sufficiently developed. The present paper describes a study to assess the photocatalytic efficacy of a new ceramic membrane containing titanium dioxide, irradiated by UV light, used to abate the pollutant load of olive mill wastewater. Good results were obtained (more than 90% of the phenol content was removed and the COD decrease was of the order of 46-51 % in 24 h) particularly using the ceramic membrane compared with those offered by analogous catalytic membranes made of metallic or polymeric materials.

Reducing the pollutant load of olive mill wastewater by photocatalytic membranes and monitoring the process using both tyrosinase biosensor and COD test

Science.gov (United States)

Martini, Elisabetta; Tomassetti, Mauro; Campanella, Luigi; Fortuna, Antonio

2013-01-01

Photocatalytic technique had already been employed in the treatment of olive mill wastewater (OMW) using the photocatalysis in suspension. The coupling of photocatalytic and membrane techniques should result in a very powerful process bringing great innovation to OMW depollution. Despite the potential advantages using these hybrid photoreactors, research on the combined use of photocatalysis and membranes has so far not been sufficiently developed. The present paper describes a study to assess the photocatalytic efficacy of a new ceramic membrane containing titanium dioxide, irradiated by UV light, used to abate the pollutant load of OMW. Good results were obtained (more than 90% of the phenol content was removed and the COD decrease was of the order of 46–51% in 24 h) particularly using the ceramic membrane compared with those offered by analogous catalytic membranes made of metallic or polymeric materials. PMID:24790964

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

Science.gov (United States)

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...

Comparison of Infectious Agents Susceptibility to Photocatalytic Effects of Nanosized Titanium and Zinc Oxides: A Practical Approach

Science.gov (United States)

Bogdan, Janusz; Zarzyńska, Joanna; Pławińska-Czarnak, Joanna

2015-08-01

Nanotechnology contributes towards a more effective eradication of pathogens that have emerged in hospitals, veterinary clinics, and food processing plants and that are resistant to traditional drugs or disinfectants. Since new methods of pathogens eradication must be invented and implemented, nanotechnology seems to have become the response to that acute need. A remarkable achievement in this field of science was the creation of self-disinfecting surfaces that base on advanced oxidation processes (AOPs). Thus, the phenomenon of photocatalysis was practically applied. Among the AOPs that have been most studied in respect of their ability to eradicate viruses, prions, bacteria, yeasts, and molds, there are the processes of TiO2/UV and ZnO/UV. Titanium dioxide (TiO2) and zinc oxide (ZnO) act as photocatalysts, after they have been powdered to nanoparticles. Ultraviolet (UV) radiation is an agent that determines their excitation. Methods using photocatalytic properties of nanosized TiO2 and ZnO prove to be highly efficient in inactivation of infectious agents. Therefore, they are being applied on a growing scale. AOP-based disinfection is regarded as a very promising tool that might help overcome problems in food hygiene and public health protection. The susceptibility of infectious agents to photocatalylic processes can be generally arranged in the following order: viruses > prions > Gram-negative bacteria > Gram-positive bacteria > yeasts > molds.

Photocatalytic surface reactions on indoor wall paint.

Science.gov (United States)

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.

Surface wettability control by titanium dioxide photo-induced reaction. Super-hydrophilic properties; Sanka chitan ni yoru hikari reiki shinsuika gijutsu. Hikari shokubai chosinsuisei

Energy Technology Data Exchange (ETDEWEB)

Watanabe, T. [The University of Tokyo, Tokyo (Japan). Research Center for Advanced Science and Technology

1999-05-01

Hydrophilicity results when the surface of titanium dioxide is reduced for the specified oxygen to be replaced by hydroxyl groups. The ease with which such a structural change occurs is subject to variation between titanium dioxide crystal surfaces, and is dependent greatly on the atmosphere. No hydrophilic trend is observed in an atmosphere of oxygen only without moisture and, in darkness without light, hydrophobicity occurs early. Although the contacta angle titanium dioxide with water with stability is not known, yet it is presumed, on the analogy of the case of strontium titanate, that it is in the range of 20-40 degrees. A hydrophilic trend below the range is attrributed to structural changes. The control of surface wettability is one of the basic tasks to fulfill in various kinds of mechanisms and manufacturing processes. The technology of wettability control using a titanium dioxide coating which is quite durable will be applied not only to functions involving defogging, dripproof, and self-cleaning, but also to the control of heat transmission in the mechanism and to the bonding process. (NEDO)

Surface wettability control by titanium dioxide photo-induced reaction. Super-hydrophilic properties. Sanka chitan ni yoru hikari reiki shinsuika gijutsu. Hikari shokubai chosinsuisei

Energy Technology Data Exchange (ETDEWEB)

Watanabe, T. (The University of Tokyo, Tokyo (Japan). Research Center for Advanced Science and Technology)

1999-05-01

Hydrophilicity results when the surface of titanium dioxide is reduced for the specified oxygen to be replaced by hydroxyl groups. The ease with which such a structural change occurs is subject to variation between titanium dioxide crystal surfaces, and is dependent greatly on the atmosphere. No hydrophilic trend is observed in an atmosphere of oxygen only without moisture and, in darkness without light, hydrophobicity occurs early. Although the contacta angle titanium dioxide with water with stability is not known, yet it is presumed, on the analogy of the case of strontium titanate, that it is in the range of 20-40 degrees. A hydrophilic trend below the range is attrributed to structural changes. The control of surface wettability is one of the basic tasks to fulfill in various kinds of mechanisms and manufacturing processes. The technology of wettability control using a titanium dioxide coating which is quite durable will be applied not only to functions involving defogging, dripproof, and self-cleaning, but also to the control of heat transmission in the mechanism and to the bonding process. (NEDO)

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

Science.gov (United States)

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.

Photocatalytic Conversion of Nitrogen to Ammonia with Water on Surface Oxygen Vacancies of Titanium Dioxide.

Science.gov (United States)

Hirakawa, Hiroaki; Hashimoto, Masaki; Shiraishi, Yasuhiro; Hirai, Takayuki

2017-08-09

Ammonia (NH 3 ) is an essential chemical in modern society. It is currently manufactured by the Haber-Bosch process using H 2 and N 2 under extremely high-pressure (>200 bar) and high-temperature (>673 K) conditions. Photocatalytic NH 3 production from water and N 2 at atmospheric pressure and room temperature is ideal. Several semiconductor photocatalysts have been proposed, but all suffer from low efficiency. Here we report that a commercially available TiO 2 with a large number of surface oxygen vacancies, when photoirradiated by UV light in pure water with N 2 , successfully produces NH 3 . The active sites for N 2 reduction are the Ti 3+ species on the oxygen vacancies. These species act as adsorption sites for N 2 and trapping sites for the photoformed conduction band electrons. These properties therefore promote efficient reduction of N 2 to NH 3 . The solar-to-chemical energy conversion efficiency is 0.02%, which is the highest efficiency among the early reported photocatalytic systems. This noble-metal-free TiO 2 system therefore shows a potential as a new artificial photosynthesis for green NH 3 production.

Synthesis, characterization and enhanced photocatalytic activity of iron oxide/carbon nanotube/Ag-doped TiO{sub 2} nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Marques Neto, José O.; Bellato, Carlos R.; Souza, Carlos H.F. de; Silva, Renê C. da; Rocha, Pablo A., E-mail: bellato@ufv.br [Universidade Federal de Viçosa (UFV), MG (Brazil)

2017-07-01

A novel magnetically recoverable catalyst (Fe/MWCNT/TiO{sub 2}-Ag) was prepared in this study by a process that involves few steps. Titanium dioxide doped with silver and iron oxide was deposited on support of multi-walled carbon nanotubes (MWCNT). The synthesized catalysts were characterized by inductively coupled plasma mass spectrometry (ICP-MS), N{sub 2} adsorption/desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), infrared spectroscopy (IR) and UV-Vis diffuse reflectance spectra (DRS). Phenol in aqueous solution (50 mg L{sup -1}) was used as a model compound for evaluation of UV-Vis (filter cut off for λ > 300 nm) photocatalytic activity. The composite catalyst has a high photocatalytic activity, destroying ca. 100% of phenol and removing 85% of total organic carbon in an aqueous solution after 180 min. The Fe/MWCNT/TiO{sub 2}-Ag catalyst remained stable, presenting an 8% decrease in phenol degradation efficiency after ten consecutive photocatalytic cycles. (author)

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

Science.gov (United States)

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)...

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

Science.gov (United States)

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...

Photocatalytic Activity of Nanotubular TiO2 Films Obtained by Anodic Oxidation: A Comparison in Gas and Liquid Phase

Directory of Open Access Journals (Sweden)

Beatriz Eugenia Sanabria Arenas

2018-03-01

Full Text Available The availability of immobilized nanostructured photocatalysts is of great importance in the purification of both polluted air and liquids (e.g., industrial wastewaters. Metal-supported titanium dioxide films with nanotubular morphology and good photocatalytic efficiency in both environments can be produced by anodic oxidation, which avoids release of nanoscale materials in the environment. Here we evaluate the effect of different anodizing procedures on the photocatalytic activity of TiO2 nanostructures in gas and liquid phases, in order to identify the most efficient and robust technique for the production of TiO2 layers with different morphologies and high photocatalytic activity in both phases. Rhodamine B and toluene were used as model pollutants in the two media, respectively. It was found that the role of the anodizing electrolyte is particularly crucial, as it provides substantial differences in the oxide specific surface area: nanotubular structures show remarkably different activities, especially in gas phase degradation reactions, and within nanotubular structures, those produced by organic electrolytes lead to better photocatalytic activity in both conditions tested.

Investigation of the thermal decomposition of a new titanium dioxide material

Czech Academy of Sciences Publication Activity Database

Palkovská, Monika; Slovák, V.; Šubrt, Jan; Boháček, Jaroslav; Barbieriková, Z.; Brezová, V.; Fajgar, Radek

2016-01-01

Roč. 125, č. 3 (2016), s. 1071-1078 ISSN 1388-6150 R&D Projects: GA ČR(CZ) GA14-20744S; GA MŠk(CZ) 7AMB14SK178 Institutional support: RVO:61388980 ; RVO:67985858 Keywords : Titanium dioxide * Rod-shaped structure * Thermal analysis * Evolved gas analysis * EPR spectroscopy Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UCHP-M) Impact factor: 1.953, year: 2016

Radioactive environmental impact assessment for a production project of titanium dioxide by chlorination process

International Nuclear Information System (INIS)

Qiu Guohua

2010-01-01

Based on the analysis of shifting direction of radionuclide in production process and the environmental investigation and monitoring, the radioactive environmental impact from a production project of titanium dioxide by chlorination process has been analyzed and assessed. The result of radioactive environmental investigation shows that values of assessment factors are in the range of environmental radioactive background. The radioactive environmental sensitive spot has been delineated. The results of radioactive environmental prediction show that the additional doses to workers and residents are 0.59 mSv/a and 9.28 × 10-4 mSv/a respectively which are less than the annual dose limits of administration. The radioactive environmental impact of the production project of the titanium dioxide by chlorination process will meet the needs of national regulations and standards if radiation protection and environmental protection measures are implemented and radioactive environmental monitoring are strengthened. (author)

Titanium dioxide as chemo-affinity chromatographic sorbent of biomolecular compounds - Applications in acidic modification-specific proteomics

DEFF Research Database (Denmark)

Engholm-Keller, Kasper; Larsen, Martin R

2011-01-01

biomolecules due to its unique ion and ligand exchange properties and high stability towards pH and temperature. Recently, titanium dioxide chromatography was introduced in proteomics as a highly specific method for enriching phosphorylated peptides - a method, which has been widely adapted by the field...... matrices for further characterization is affinity chromatography, which relies on the specific interaction between an analyte in solution and a solid adsorbent. Titanium dioxide-based affinity chromatography has proven to be a versatile tool in enrichment of various compounds such as phosphorylated....... The development of TiO(2)-based chromatographic strategies for separation of various biomolecules from its introduction for small molecules more than 20years ago until recent proteomics applications today will be reviewed here....

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

Science.gov (United States)

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,...

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

Science.gov (United States)

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...

In vitro assessment of photocatalytic titanium oxide surface modified stainless steel orthodontic brackets for antiadherent and antibacterial properties against Lactobacillus acidophilus.

Science.gov (United States)

Shah, Alok Girish; Shetty, Pradeep Chandra; Ramachandra, C S; Bhat, N Sham; Laxmikanth, S M

2011-11-01

To assess the antiadherent and antibacterial properties of surface modified stainless steel orthodontic brackets with photocatalytic titanium oxide (TiO(2)) against Lactobacillus acidophilus. This study was done on 120 specimens of stainless steel preadjusted edgewise appliance (PEA) orthodontic brackets. The specimens were divided into four test groups. Each group consisted of 30 specimens. Groups containing uncoated brackets acted as a control group for their respective experimental group containing coated brackets. Surface modification of brackets was carried out by the radiofrequency (RF) magnetron sputtering method with photocatalytic TiO(2). Brackets then were subjected to microbiological tests for assessment of the antiadherent and antibacterial properties of photocatalytic TiO(2) coating against L acidophilus. Orthodontic brackets coated with photocatalytic TiO(2) showed an antiadherent effect against L acidophilus compared with uncoated brackets. The bacterial mass that was bound to the TiO(2)-coated brackets was less when compared with the uncoated brackets. Furthermore, TiO(2)-coated brackets had a bactericidal effect on L acidophilus, which causes dental caries. Surface modification of orthodontic brackets with photocatalytic TiO(2) can be used to prevent the accumulation of dental plaque and the development of dental caries during orthodontic treatment.

Effect of TiO2 photocatalytic preservation on quality of kiwifruit during shelf life

Science.gov (United States)

Hou, Chengjie; Jiang, Yong; Qi, Shasha; Zhang, Changfeng; Guo, Fengjun

2018-04-01

In order to study the effect of titanium dioxide photocatalysis technology on the quality of kiwifruit during shelf life, the texture properties of kiwifruit during shelf life were measured by simulating the effect of cross-ripening among fruits and vegetables under the mixed environment of different fruits and vegetables. The results showed that the kiwifruit after photocatalytic preservation maintained a more mature state in the middle and preliminary stage of shelf life, chewiness is better than the control group and the blank group, compared with the over-ripen control group and low-maturity blank group, experimental group has the best commodity value. Therefore, using nanometer photocatalytic preservation can effectively reduce the ripening effect of kiwifruit in the mixed environment, control the after-ripening of kiwifruit, and meanwhile maintain the commodity value of the kiwifruit during the shelf life.iO2, Photocatalysis, Kiwifruit, Shelf-life.

Enhancing the photoresponse and photocatalytic properties of TiO₂ by controllably tuning defects across {101} facets

Energy Technology Data Exchange (ETDEWEB)

Wan, Piaopiao [Chongqing Univ. (China). College of Materials Science and Engineering and Electron Microscopy Center; Hood, Zachary D. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemistry and Biochemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Adhikari, Shiba P. [Wake Forest Univ., Winston-Salem, NC (United States). Dept. of Chemistry and Center for Energy, Environment, and Sustainability (CEES); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division, Carbon and Composites; Xu, Yunfan [Tsinghua Univ., Beijing (China). Lab. of Advanced Materials and Dept. of Materials Science and Engineering; Yang, Shize [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Wu, Sujuan [Chongqing Univ. (China). College of Materials Science and Engineering and Electron Microscopy Center

2018-03-15

Introducing defects into semiconductors with well-controlled exposed facets offers an effective route for the development of photocatalytic materials with greatly improved properties. Here, we report a facile ethylene glycol reduction procedure to make anatase titanium dioxide (TiO₂) with different concentrations of exposed {001} and {101} facets, leading to different surficial defects. TiO₂ with increased concentrations of {101} facets shows a 5-fold improvement in photocurrent generation as well as improved photocatalytic activity towards water splitting under visible light irradiation. Thus, the improved activity is ascribed to the oxygen vacancies as well as the variable surface chemical states, which collectively induce a slower recombination rate of photo-induced electron-hole pairs. This work also highlights a feasible strategy to obtain the defective TiO₂ and explore the synergistic effect of surface defects and different concentrations of exposed {001} and {101} facets for photocurrent and photocatalytic properties under visible light irradiation.

Titanium dioxide antireflection coating for silicon solar cells by spray deposition

Science.gov (United States)

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.

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

Science.gov (United States)

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.

The influence of adding modified zirconium oxide-titanium dioxide nano-particles on mechanical properties of orthodontic adhesive: an in vitro study

OpenAIRE

Felemban, Nayef H.; Ebrahim, Mohamed I.

2017-01-01

Background The purpose of this in-vitro study was to examine the effect of incorporating different concentrations of Zirconium oxide-Titanium dioxide (ZrO2-TiO2) nanoparticles, which can have antibacterial properties, on the mechanical properties of an orthodontic adhesive. Methods ZrO2-TiO2 (Zirconium oxide, HWNANO, Hongwu International Group Ltd, China) -Titanium dioxide, Nanoshell, USA) nanopowder were incorporated into orthodontic adhesive (Transbond XT, 3?M Unitek, Monrovia, USA) with di...

Size-mediated cytotoxicity of nanocrystalline titanium dioxide, pure and zinc-doped hydroxyapatite nanoparticles in human hepatoma cells

International Nuclear Information System (INIS)

Devanand Venkatasubbu, G.; Ramasamy, S.; Avadhani, G. S.; Palanikumar, L.; Kumar, J.

2012-01-01

Nanoparticles are highly used in biological applications including nanomedicine. In this present study, the interaction of HepG2 hepatocellular carcinoma cells (HCC) with hydroxyapatite (HAp), zinc-doped hydroxyapatite, and titanium dioxide (TiO 2 ) nanoparticles were investigated. Hydroxyapatite, zinc-doped hydroxyapatite and titanium dioxide nanoparticles were prepared by wet precipitation method. They were subjected to isochronal annealing at different temperatures. Particle morphology and size distribution were characterized by X-ray diffraction and transmission electron microscope. The nanoparticles were co-cultured with HepG2 cells. MTT assay was employed to evaluate the proliferation of tumor cells. The DNA damaging effect of HAp, Zn-doped HAp, and TiO 2 nanoparticles in human hepatoma cells (HepG2) were evaluated using DNA fragmentation studies. The results showed that in HepG2 cells, the anti-tumor activity strongly depend on the size of nanoparticles in HCC cells. Cell cycle arrest analysis for HAp, zinc-doped HAp, and TiO 2 nanoparticles revealed the influence of HAp, zinc-doped HAp, and titanium dioxide nanoparticles on the apoptosis of HepG2 cells. The results imply that the novel nano nature effect plays an important role in the biomedicinal application of nanoparticles.

Synthesis of dye-sensitized solar cells. Efficiency cells as a thickness of titanium dioxide

Directory of Open Access Journals (Sweden)

Szura Dominika

2017-01-01

Full Text Available Defying the influence of the thickness of TiO2 efficiency of dye-sensitized solar cell. It was confirmed that the compatibility of printed layers with the parameters closely related with the DSSC. It was found that the increase in thickness of the titanium dioxide layer, increases the distance between the electrodes, determined by the thickness of the Surlyn foil. With the rise of thickness of dyed layer of TiO2 established decrease in the value of its transmittance. Greatest transparency and aesthetic value obtained for photovoltaic modules with a single layer of titanium dioxide. The improved performance efficiency and preferred yields maximum power were noticed and exhibited by the cells covered with three layers of TiO2. It was established that the behaviour of economic efficiency in the production process, provides a range of cells with two layers of oxide, showing a similar performance and greater transparency.

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

Science.gov (United States)

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.

Supporting nanomaterial risk assessment by case studies of nano-titanium dioxide using comprehensive environmental assessment

Science.gov (United States)

Here we describe a comprehensive environmental assessment (CEA) approach for two case studies of nano-titanium dioxide (nano-TiO2) in real world applications: water treatment and sunscreen. CEA combines a product life cycle framework with the risk assessment paradigm.

Reducing the pollutant load of olive mill wastewater by photocatalytic membranes and monitoring the process using both tyrosinase biosensor and COD test

Directory of Open Access Journals (Sweden)

Elisabetta eMartini

2013-12-01

Full Text Available Photocatalytic technique had already been employed in the treatment of olive mill wastewater (OMW using the photocatalysis in suspension. The coupling of photocatalytic and membrane techniques should result in a very powerful process bringing great innovation to OMW depollution. Despite the potential advantages using these hybrid photoreactors, research on the combined use of photocatalysis and membranes has so far not been sufficiently developed. The present paper describes a study to assess the photocatalytic efficacy of a new ceramic membrane containing titanium dioxide, irradiated by UV light, used to abate the pollutant load of olive mill wastewater. Good results were obtained (more than 90% of the phenol content was removed and the COD decrease was of the order of 46-51 % in 24 h particularly using the ceramic membrane compared with those offered by analogous catalytic membranes made of metallic or polymeric materials.

Evaluation of synergy and bacterial regrowth in photocatalytic ozonation disinfection of municipal wastewater.

Science.gov (United States)

Mecha, Achisa C; Onyango, Maurice S; Ochieng, Aoyi; Momba, Maggy N B

2017-12-01

The use of solar and ultraviolet titanium dioxide photocatalytic ozonation processes to inactivate waterborne pathogens (Escherichia coli, Salmonella species, Shigella species and Vibrio cholerae) in synthetic water and secondary municipal wastewater effluent is presented. The performance indicators were bacterial inactivation efficiency, post-disinfection regrowth and synergy effects (collaboration) between ozonation and photocatalysis (photocatalytic ozonation). Photocatalytic ozonation effectively inactivated the target bacteria and positive synergistic interactions were observed, leading to synergy indices (SI) of up to 1.86 indicating a performance much higher than that of ozonation and photocatalysis individually (SI≤1, no synergy; SI>1 shows synergy between the two processes). Furthermore, there was a substantial reduction in contact time required for complete bacterial inactivation by 50-75% compared to the individual unit processes of ozonation and photocatalysis. Moreover, no post-treatment bacterial regrowth after 24 and 48h in the dark was observed. Therefore, the combined processes overcame the limitations of the individual unit processes in terms of the suppression of bacterial reactivation and regrowth owing to the fact that bacterial cells were irreparably damaged. The treated wastewater satisfied the bacteriological requirements in treated wastewater for South Africa. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

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.

Synthesis of Titanium Dioxide nanoparticles via sucrose ester micelle-mediated hydrothermal processing route

International Nuclear Information System (INIS)

Anwar, N.S.; Kassim, A.; Lim, H.N.; Zakarya, S.A.; Huang, N.M.

2010-01-01

Titanium dioxide nanoparticles were synthesized via low-temperature sucrose ester micelle-mediated hydrothermal processing route using titanium isopropoxide as the precursor. X-ray diffractometer revealed that the samples possessed a mixed crystalline phases consisting of anatase and brookite in which anatase was the main phase. Upon increasing the hydrothermal reaction temperature, the degree of crystallinity of the nanoparticles improved and their morphology transformed from bundles of needles to rods and to spheres. Photo catalytic behaviour of the as-synthesized nanoparticles was investigated by photodegradation of methylene blue solution in an ultraviolet A irradiating photo reactor. The as-synthesized nanoparticles exhibited higher photo catalytic performance as compared to the commercial counterpart. (author)

Characterization of titanium dioxide nanoparticles in food products: Analytical methods to define nanoparticles

NARCIS (Netherlands)

Peters, R.J.B.; Bemmel, G. van; Herrera-Rivera, Z.; Helsper, H.P.F.G.; Marvin, H.J.P.; Weigel, S.; Tromp, P.C.; Oomen, A.G.; Rietveld, A.G.; Bouwmeester, H.

2014-01-01

Titanium dioxide (TiO2) is a common food additive used to enhance the white color, brightness, and sometimes flavor of a variety of food products. In this study 7 food grade TiO2 materials (E171), 24 food products, and 3 personal care products were investigated for their TiO 2 content and the

Characterization of Titanium Dioxide Nanoparticles in Food Products: Analytical Methods To Define Nanoparticles

NARCIS (Netherlands)

Peters, R.J.B.; Bemmel, van M.E.M.; Herrera-Rivera, Z.; Helsper, J.P.F.G.; Marvin, H.J.P.; Weigel, S.; Tromp, P.C.; Oomen, A.G.; Rietveld, A.G.; Bouwmeester, H.

2014-01-01

Titanium dioxide (TiO2) is a common food additive used to enhance the white color, brightness, and sometimes flavor of a variety of food products. In this study 7 food grade TiO2 materials (E171), 24 food products, and 3 personal care products were investigated for their TiO2 content and the

Electron-Poor Thiophene 1,1-Dioxides: Synthesis, Characterization, and Application as Electron Relays in Photocatalytic Hydrogen Generation.

Science.gov (United States)

Tsai, Chia-Hua; Chirdon, Danielle N; Kagalwala, Husain N; Maurer, Andrew B; Kaur, Aman; Pintauer, Tomislav; Bernhard, Stefan; Noonan, Kevin J T

2015-08-03

The synthesis and characterization of electron-poor thiophene 1,1-dioxides bearing cyanated phenyl groups are reported. The electron-accepting nature of these compounds was evaluated by cyclic voltammetry, and highly reversible and facile reductions were observed for several derivatives. Moreover, some of the reduced thiophene dioxides form colorful anions, which were investigated spectroelectrochemically. Photoluminescence spectra of the electron-deficient sulfones were measured in CH2 Cl2, and they emit in the blue-green region with significant variation in the quantum yield depending on the aryl substituents. By expanding the degree of substitution on the phenyl rings, quantum yields up to 34 % were obtained. X-ray diffraction data are reported for two of the thiophene 1,1-dioxides, and the electronic structure was probed for all synthesized derivatives through DFT calculations. The dioxides were also examined as electron relays in a photocatalytic water reduction reaction, and they showed potential to boost the efficiency. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bactericidal effect of the photocatalystic reaction of titanium dioxide using visible wavelengths on Streptococcus mutans biofilm.

Science.gov (United States)

Kim, Chan-Hee; Lee, Eun-Song; Kang, Si-Mook; de Josselin de Jong, Elbert; Kim, Baek-Il

2017-06-01

The aim of this study was to determine the effect of titanium dioxide (TiO 2 ) photocatalysis induced by the application of clinically acceptable visible light at 405nm on the growth of Streptococcus mutans biofilms. S. mutans biofilms were grown on a hydroxyapatite (HA) disk and deposited in a rutile-type TiO 2 solution at a concentration of 0.1mg/mL. TiO 2 photocatalysis was measured for exposure to visible light (405nm) and ultraviolet (UV) light (254nm) produced by light-emitting diodes for 10, 20, 30, and 40min. After two treatments, the number of colonies formed in the final S. mutans biofilm on the HA disk were measured to confirm their viability, and the morphological changes of S. mutans were evaluated using scanning electronic microscopy. The bactericidal effects of 254- and 405-nm light resulted in > 5-log and 4-log reductions, respectively (p7-log reduction after 40min of treatment in both treatment groups relative to the control group. It was confirmed that the antibacterial effect could be shown by causing the photocatalytic reaction of TiO 2 in S. mutans biofilm even at the wavelength of visible light (405nm) as at the wavelength of ultraviolet light (254nm). Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of the human cerebrospinal fluid phosphoproteome by titanium dioxide affinity chromatography and mass spectrometry

DEFF Research Database (Denmark)

Bahl, Justyna Maria Czarna; Jensen, Søren Skov; Larsen, Martin R

2008-01-01

of phosphorylation aberrations in health and disease. Toward that goal we here describe a method for a comprehensive isolation and identification of phosphorylated tryptic peptides derived from CSF proteins using a simple sample preparation step and titanium dioxide-affinity chromatography followed by MALDI...

Surface modification of nanoporous anodic alumina photonic crystals for photocatalytic applications

Science.gov (United States)

Lim, Siew Yee; Law, Cheryl Suwen; Santos, Abel

2018-01-01

Herein, we report on the development of a rationally designed composite photocatalyst material by combining nanoporous anodic alumina-rugate filters (NAA-RFs) with photo-active layers of titanium dioxide (TiO2). NAA-RFs are synthesised by sinusoidal pulse anodisation and subsequently functionalised with TiO2 by sol-gel method to provide the photonic structures with photocatalytic properties. We demonstrate that the characteristic photonic stopband (PSB) of the surface-modified NAA-RFs can be precisely tuned across the UV-visible-NIR spectrum to enhance the photon-toelectron conversion of TiO2 by `slow photon effect'. We systematically investigate the effect of the anodisation parameters (i.e. anodisation period and pore widening time) on the position of the PSB of NAA-RFs as well as the photocatalytic performances displayed by these photonic crystal structures. When the edges of the PSB of surfacemodified NAA-RFs are positioned closely to the absorption peak of the model organic dye (i.e. methyl orange - MO), the photocatalytic performance of the system to degrade these molecules is enhanced under simulated solar light irradiation due to slow photon effect. Our investigation also reveals that the photocatalytic activity of surface-modified NAA-RFs is independent of slow photon effect and enhances with increasing period length (i.e. increasing anodisation period) of the photonic structures when there is no overlap between the PSB and the absorption peak of MO. This study therefore provides a rationale towards the photocatalytic enhancement of photonic crystals by a rational design of the PSB, creating new opportunities for the future development of high-performance photocatalysts.

Synthesis and photocatalytic activity of ytterbium-doped titania/diatomite composite photocatalysts

Science.gov (United States)

Tang, Wenjian; Qiu, Kehui; Zhang, Peicong; Yuan, Xiqiang

2016-01-01

Ytterbium-doped titanium dioxide (Yb-TiO2)/diatomite composite materials with different Yb concentrations were prepared by sol-gel method. The phase structure, morphology, and chemical composition of the as-prepared composites were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and ultraviolet-visible (UV-vis) diffuse reflection spectroscopy. The XRD and Raman spectroscopy analysis indicated that the TiO2 existed in the form of pure anatase in the composites. The SEM images exhibited the well deposition and dispersion of TiO2 nanoparticles with little agglomeration on the surfaces of diatoms. The UV-vis diffuse reflection spectra showed that the band gap of TiO2 could be narrowed by the introduction of Yb species, which was further affected by doping concentration of Yb. The photocatalytic activity of synthesized samples was investigated by the degradation of methylene blue (MB) under UV light irradiation. It was observed that the photocatalytic degradation followed a pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. Compared to TiO2 and TiO2/diatomite, the Yb-TiO2/diatomite composites exhibited higher photocatalytic activity toward degradation of MB using UV light irradiation.

Reactivity of Trapped and Accumulated Electrons in Titanium Dioxide Photocatalysis

Directory of Open Access Journals (Sweden)

Shigeru Kohtani

2017-10-01

Full Text Available Electrons, photogenerated in conduction bands (CB and trapped in electron trap defects (Tids in titanium dioxide (TiO2, play crucial roles in characteristic reductive reactions. This review summarizes the recent progress in the research on electron transfer in photo-excited TiO2. Particularly, the reactivity of electrons accumulated in CB and trapped at Tids on TiO2 is highlighted in the reduction of molecular oxygen and molecular nitrogen, and the hydrogenation and dehalogenation of organic substrates. Finally, the prospects for developing highly active TiO2 photocatalysts are discussed.

Electrowinning molten titanium from titanium dioxide

CSIR Research Space (South Africa)

Van Vuuren, DS

2005-10-01

Full Text Available the Manufacturing and Materials Industry in it quest for global competitiveness CSIR Manufacturing and Materials Technology 3 Rationale – Titanium Cost Build-up Material Cost Ilmenite $0.27/kg Ti sponge Titanium slag $0.75/kg Ti Sponge TiCl4 and TiO2 $3....10/kg Ti Sponge Ti Sponge raw materials costs $5.50/kg Ti Sponge Total Ti Sponge cost $9-$11/kg Ti Sponge Ti ingot $15-17/kg Ti Aluminium $1.7/kg Al Supporting the Manufacturing and Materials Industry in its quest for global competitivenessorting...

Colloidal Plasmonic Titanium Nitride Nanoparticles: Properties and Applications

Directory of Open Access Journals (Sweden)

Guler Urcan

2015-01-01

Full Text Available Optical properties of colloidal plasmonic titanium nitride nanoparticles are examined with an eye on their photothermal and photocatalytic applications via transmission electron microscopy and optical transmittance measurements. Single crystal titanium nitride cubic nanoparticles with an average size of 50 nm, which was found to be the optimum size for cellular uptake with gold nanoparticles [1], exhibit plasmon resonance in the biological transparency window and demonstrate a high absorption efficiency. A self-passivating native oxide at the surface of the nanoparticles provides an additional degree of freedom for surface functionalization. The titanium oxide shell surrounding the plasmonic core can create new opportunities for photocatalytic applications.

Photocatalytic antibacterial effects on TiO2-anatase upon UV-A and UV-A/VIS threshold irradiation.

Science.gov (United States)

Wu, Yanyun; Geis-Gerstorfer, Jürgen; Scheideler, Lutz; Rupp, Frank

2016-01-01

Photocatalysis mediated by the anatase modification of titanium dioxide (TiO2) has shown antibacterial effects in medical applications. The aim of this study was to investigate the possibility of expanding the excitation wavelengths for photocatalytic antibacterial effects from ultraviolet (UV) into the visible light range. After deposition of salivary pellicle and adhesion of Streptococcus gordonii on anatase, different irradiation protocols were applied to induce photocatalysis: ultraviolet A (UV-A) > 320 nm; ultraviolet/visible (UV-A/VIS) light > 380 nm and > 390 nm; and VIS light 400-410 nm. A quartz crystal microbalance with dissipation (QCM-D) tests and microscopic examination were used to observe the photoinduced antibacterial effects. Salivary pellicle could be photocatalytically decomposed under all irradiation protocols. In contrast, effective photocatalytic attack of bacteria could be observed by UV-A as well as by UV-A/VIS at 380 nm < λ < 390 nm only. Wavelengths above 380 nm show promise for in situ therapeutic antifouling applications.

Binding of plasma proteins to titanium dioxide nanotubes with different diameters

Science.gov (United States)

Kulkarni, Mukta; Flašker, Ajda; Lokar, Maruša; Mrak-Poljšak, Katjuša; Mazare, Anca; Artenjak, Andrej; Čučnik, Saša; Kralj, Slavko; Velikonja, Aljaž; Schmuki, Patrik; Kralj-Iglič, Veronika; Sodin-Semrl, Snezna; Iglič, Aleš

2015-01-01

Titanium and titanium alloys are considered to be one of the most applicable materials in medical devices because of their suitable properties, most importantly high corrosion resistance and the specific combination of strength with biocompatibility. In order to improve the biocompatibility of titanium surfaces, the current report initially focuses on specifying the topography of titanium dioxide (TiO2) nanotubes (NTs) by electrochemical anodization. The zeta potential (ζ-potential) of NTs showed a negative value and confirmed the agreement between the measured and theoretically predicted dependence of ζ-potential on salt concentration, whereby the absolute value of ζ-potential diminished with increasing salt concentrations. We investigated binding of various plasma proteins with different sizes and charges using the bicinchoninic acid assay and immunofluorescence microscopy. Results showed effective and comparatively higher protein binding to NTs with 100 nm diameters (compared to 50 or 15 nm). We also showed a dose-dependent effect of serum amyloid A protein binding to NTs. These results and theoretical calculations of total available surface area for binding of proteins indicate that the largest surface area (also considering the NT lengths) is available for 100 nm NTs, with decreasing surface area for 50 and 15 nm NTs. These current investigations will have an impact on increasing the binding ability of biomedical devices in the body leading to increased durability of biomedical devices. PMID:25733829

Food contact surfaces coated with nitrogen-doped titanium dioxide: effect on Listeria monocytogenes survival under different light sources

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, D.; Teixeira, P. [Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Tavares, C.J. [Center of Physics, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); Azeredo, J., E-mail: jazeredo@deb.uminho.pt [Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

2013-04-01

Improvement of food safety is a very important issue, and is on the basis of production and application of new/modified food contact surfaces. Titanium dioxide (TiO{sub 2}) and, more recently, nitrogen-doped titanium dioxide (N-TiO{sub 2}) coatings are among the possible forms to enhance food contact surfaces performance in terms of higher hygiene and easier sanitation. In this context, the present work aimed at evaluating the bactericidal activity of an N-TiO{sub 2} coating on glass and stainless steel under two different sources of visible light – fluorescent and incandescent – and ultraviolet (UV) irradiation. Listeria monocytogenes was chosen as representative of major foodborne pathogens and its survival was tested on N-TiO{sub 2} coated coupons. In terms of survival percentage, good results were obtained after exposure of coated surfaces to all light types since, apart from the value obtained after exposing glass to fluorescent light (56.3%), survival rates were always below 50%. However, no effective disinfection was obtained, given that for a disinfectant or sanitizing agent to be claimed as effective it needs to be able to promote at least a 3-log reduction of the microbial load, which was not observed for any of the experimental conditions assessed. Even so, UV irradiation was the most successful on eliminating cells on coated surfaces, since the amount of bacteria was reduced to 1.49 × 10{sup 6} CFU/ml on glass and 2.37 × 10{sup 7} on stainless steel. In contrast, both visible light sources had only slightly decreased the amount of viable cells, which remained in the range of 8 log CFU/ml. Hence, although some bactericidal effect was accomplished under visible light, UV was the most effective light source on promoting photocatalytic reactions on N-TiO{sub 2} coated coupons and none of the experimental conditions have reached a satisfactory disinfection level. Thus, this surface coating needs further research and improvement in order to become truly

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

Science.gov (United States)

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...

Point Defects in 3D and 1D Nanomaterials: The Model Case of Titanium Dioxide

International Nuclear Information System (INIS)

Knauth, Philippe

2010-01-01

Titanium dioxide is one of the most important oxides for applications in energy and environment, such as solar cells, photocatalysis, lithium-ion batteries. In recent years, new forms of titanium dioxide with unusual structure and/or morphology have been developed, including nanocrystals, nanotubes or nanowires. We have studied in detail the point defect chemistry in nanocrystalline TiO 2 powders and ceramics. There can be a change from predominant Frenkel to Schottky disorder, depending on the experimental conditions, e.g. temperature and oxygen partial pressure. We have also studied the local environment of various dopants with similar ion radius, but different ion charge (Zn 2+ , Y 3+ , Sn 4+ , Zr 4+ , Nb 5+ ) in TiO 2 nanopowders and nanoceramics by Extended X-Ray Absorption Fine Structure (EXAFS) Spectroscopy. Interfacial segregation of acceptors was demonstrated, but donors and isovalent ions do not segregate. An electrostatic 'space charge' segregation model is applied, which explains well the observed phenomena.

Low irradiance photocatalytic degradation of toluene in air by screen-printed titanium dioxide layers

International Nuclear Information System (INIS)

Strini, Alberto; Sanson, Alessandra; Mercadelli, Elisa; Sangiorgi, Alex; Schiavi, Luca

2013-01-01

Screen-printed titania photocatalytic layers made from Degussa P25 were studied in order to assess the potential of this deposition technology for the production of catalytic surfaces for airborne pollutant degradation. The deposited catalytic TiO 2 layers were characterized by a low density (about 25% of the titania bulk crystal) typical of very porous films. The study was carried out using toluene at low concentration (12 ppb) as model pollutant and with a low UV-A irradiance level on the sample surface (200 μW cm −2 ). The catalyst layers were deposited on alumina and quartz substrates demonstrating a good catalytic depollution activity. The relationship between the layer thickness and the catalytic activity was studied in the 1 to 6.8 μm range indicating an optimal 3–4 μm film thickness. Thicker layers do not show significant increases in the catalytic activity. The optical transmittance was studied using quartz substrate samples, showing a severely reduced photon flux for layers deeper than 5 μm. The effect of post-printing thermal treatment was studied in the 500–900 °C range, demonstrating good catalytic activity for processing temperatures ≤ 700 °C. These results indicate that the screen-printing process can be a promising technology for the realization of high efficiency photocatalytic materials for air depollution applications at low UV-A irradiance. - Highlights: • Screen-printed TiO 2 has a good catalytic activity in toluene air depollution. • The overall density of screen-printed TiO 2 layer is ∼ 25% of the bulk crystal density. • The catalytic activity is demonstrated at low UV-A irradiance (200 µW cm –2 ). • The catalytic activity is dependent on the layer thickness until ∼ 4 µm thickness. • The catalytic layer has good activity up to 700 °C post-printing thermal treatment

Gas-phase Crystallization of Titanium Dioxide Nanoparticles

International Nuclear Information System (INIS)

Ahonen, P.P.; Moisala, A.; Tapper, U.; Brown, D.P.; Jokiniemi, J.K.; Kauppinen, E.I.

2002-01-01

We have investigated the development of crystal morphology and phase in ultrafine titanium dioxide particles. The particles were produced by a droplet-to-particle method starting from propanolic titanium tetraisopropoxide solution, and calcined in a vertical aerosol reactor in air. Mobility size classified 40-nm diameter particles were conveyed to the aerosol reactor to investigate particle size changes at 20-1200 deg. C with 5-1-s residence time. In addition, polydisperse particles were used to study morphology and phase formation by electron microscopy. According to differential mobility analysis, the particle diameter was reduced to 21-23-nm at 600 deg. C and above. Precursor decomposition occurred between 20 deg. C and 500 deg. C. The increased mobility particle size at 700 deg. C and above was observed to coincide with irregular particles at 700 deg. C and 800 deg. C and faceted particles between 900 deg. C and 1200 deg. C, according to transmission electron microscopy. The faceted anatase particles were observed to approach a minimized surface energy by forming {101} and {001} crystallographic surfaces. Anatase phase was observed at 500-1200 deg. C and above 600 deg. C the particles were single crystals. Indications of minor rutile formation were observed at 1200 deg. C. The relatively stable anatase phase vs. temperature is attributed to the defect free structure of the observed particles and a lack of crystal-crystal attachment points

Colloidal Plasmonic Titanium Nitride Nanoparticles: Properties and Applications

DEFF Research Database (Denmark)

Guler, Urcan; Suslov, Sergey; Kildishev, Alexander V.

2015-01-01

Optical properties of colloidal plasmonic titanium nitride nanoparticles are examined with an eye on their photothermal and photocatalytic applications via transmission electron microscopy and optical transmittance measurements. Single crystal titanium nitride cubic nanoparticles with an average ...

Optical, Physical, and Chemical Properties of Surface Modified Titanium Dioxide Powders

Science.gov (United States)

2011-02-01

PROPERTIES OF SURFACE MODIFIED TITANIUM DIOXIDE POWDERS fwn Scivrxc fa SciWcrrs Brendan G. DeLacy RESEARCH AND TECHNOLOGY DIRECTORATE David R. Redding ...NUMBER 5c PROGRAM ELEMENT NUMBER 6. AUTHOR(S) DeLacy, Brendan G. (SAIC) Redding , David R. (ECBC); and Matthews. Joshua 5d. PROJECT NUMBER...X3,300?t>5flm* ** aJI ^-15 SEf Figure 7 - SEM Image #1 of CR-470 •i i .#1. • ^ iW i > hp ^•R^^^Ay *£ $ ^< W^# K HB8 %^ vj\\ X

Toxicity and Fate Comparison between Several Brass and Titanium Dioxide Powders

Science.gov (United States)

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

[Influence of titanium dioxide activated under visible light on survival of mold fungi].

Science.gov (United States)

Kądziołka, Daria; Rokicka, Paulina; Markowska-Szczupak, Agata; Morawski, Antoni W

2018-01-01

In public and residential buildings, fungi are usually found in the dust or growing on building materials medium such. It has been known that a number of their spores may contaminate the indoor environment and deteriorate air quality in accommodation spaces. Previously designed air cleaning systems do not guarantee a complete removal of agents harmful to humans and animals. Therefore, there is a great need to develop a new solution to remove molds from indoor air. In recent years, photocatalysis based on titanium dioxide (TiO2) has been proposed as an effective method for air pollutants removal. The aim of the study was to determine the effect of TiO2 activated under artificial sun light (UV-VIS - ultraviolet - visible spectroscopy) on survival of fungi Penicillium chrysogenum and Aspergillus niger. The commercial P 25 (Aeroxide P 25, Evonik, Germany) and nitrogen modified titanium dioxide (N-TiO2) were used. The microbiological study was performed using Penicillium chrysogenum and Aspergillus niger fungi. The survival of fungi was determined on the basis of changes in their concentration. It was found that N-TiO2 has a stronger antifungal activity against P. chrysogenum and A. niger than P 25. For N-TiO2, the complete elimination of molds was possible after 3 h under artificial solar light activation. The minimal concentration of photocatalyst was 0.01 g×dm-3 (P. chrysogenum) and 0.1 g×dm-3 (A. niger). The nitrogen modification of titanium dioxide produced expected results and N-TiO2 presented good antifungal activity. The findings of the presented investigation can lead to the development of air filter to be used for removal of harmful agents (including molds) from indoor environment. Med Pr 2018;69(1):59-65. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Photocatalytic degradation of p-phenylenediamine with TiO2-coated magnetic PMMA microspheres in an aqueous solution

International Nuclear Information System (INIS)

Chen, Y.-H.; Liu, Y.-Y.; Lin, R.-H.; Yen, F.-S.

2009-01-01

This study investigates the photocatalytic degradation of p-phenylenediamine (PPD) with titanium dioxide-coated magnetic poly(methyl methacrylate) (TiO 2 /mPMMA) microspheres. The TiO 2 /mPMMA microspheres are employed as novel photocatalysts with the advantages of high photocatalytic activity, magnetic separability, and good durability. The scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and transmission electron microscopy (TEM) images of the TiO 2 /mPMMA microspheres are used to characterize the morphology, element content, and distribution patterns of magnetite and TiO 2 nanoparticles. The BET-specific surface area and saturation magnetization of the TiO 2 /mPMMA microspheres are observed as 2.21 m 2 /g and 4.81 emu/g, respectively. The photocatalytic degradation of PPD are performed under various experimental conditions to examine the effects of initial PPD concentration, TiO 2 /mPMMA microsphere dosage, and illumination condition on the eliminations of PPD and chemical oxygen demand (COD) concentrations. Good repeatability of photocatalytic performance with the use of the TiO 2 /mPMMA microspheres has been demonstrated in the multi-run experiments. The photocatalytic kinetics for the reductions of PPD and COD associated with the initial PPD concentration, UV radiation intensity, and TiO 2 /mPMMA microsphere dosage are proposed. The relationships between the reduction percentages of COD and PPD are clearly presented

Basic research for nuclear energy : a study on photo-catalytic decomposition reactions of organics dissolved in water

Energy Technology Data Exchange (ETDEWEB)

Sung, K. W.; Na, J. W.; Cho, Y. H.; Kim, K. R

1999-01-01

In an experiment on TiO{sub 2} photo-catalysis of five nitrogen-containing organic compounds, the changes of pH and total carbon contents were measured, and the dependence of their photo-catalytic characteristic upon their chemical structures were investigated. -- calculation of the effect of ionic carbon species in an aqueous solution on thermodynamic equilibrium, pH and conductivity showed a small quantity of organics could lead conductivity increase and pH reduction. -- Based on the results of photo-catalytic experiment of ethylamine, phenylhydrazine, pyridine, urea or EDTA, irradiated for 180 minutes after adsorption onto titanium dioxide for 60 minutes, relationship between nitrogen atomic charge and the first-order rate constant was as the following: R (1st - order rate constant) = {delta} ({epsilon} - a ){sup 1/3} + b where, {epsilon} : atomic charge of nitrogen in a molecular, {delta}, a and b : corrective coefficients.

Catalytic Efficiency of Titanium Dioxide (TiO2) and Zeolite ZSM-5 Catalysts in the in-situ Epoxidation of Palm Olein

Science.gov (United States)

Yunus, M. Z. Mohd; Jamaludin, S. K.; Abd. Karim, S. F.; Gani, A. Abd; Sauki, A.

2018-05-01

Titanium dioxide and zeolite ZSM-5 are the commonly used heterogeneous catalysts in many chemical reactions. They have several advantages such as low cost and environmental friendly. In this study, titanium dioxide and zeolite ZSM-5 act as catalyst in the in-situ epoxidation of palm olein. Epoxidation of palm olein was carried out by using in-situ generated performic acid to produce epoxidized palm olein in a semi-batch reactor at different temperatures (45°C and 60°C) and agitation speed of 400 rpm. The effects of both catalysts are studied to compare their efficiency in catalyzing the in-situ epoxidation. Epoxidized palm olein was analyzed by using percent of relative conversion to oxirane (RCO%) and fourier transform infrared spectroscopy (FTIR). Surface area of the catalysts used were then characterized by using BET. The results indicated that titanium dioxide is a better catalyst in the in-situ epoxidation of palm olein since it provides higher RCO% compared to Zeolite ZSM-5 at 45°C.

High-rate deposition of photocatalytic TiO2 films by oxygen plasma assist reactive evaporation method

International Nuclear Information System (INIS)

Sakai, Tetsuya; Kuniyoshi, Yuji; Aoki, Wataru; Ezoe, Sho; Endo, Tatsuya; Hoshi, Yoichi

2008-01-01

High-rate deposition of titanium dioxide (TiO 2 ) film was attempted using oxygen plasma assisted reactive evaporation (OPARE) method. Photocatalytic properties of the film were investigated. During the deposition, the substrate temperature was fixed at 400 deg. C. The film deposition rate can be increased by increasing the supply of titanium atoms to the substrate, although oversupply of the titanium atoms causes oxygen deficiency in the films, which limits the deposition rate. The film structure depends strongly on the supply ratio of oxygen molecules to titanium atoms O 2 /Ti and changes from anatase to rutile structure as the O 2 /Ti supply ratio increased. Consequently, the maximum deposition rates of 77.0 nm min -1 and 145.0 nm min -1 were obtained, respectively, for the anatase and rutile film. Both films deposited at such high rates showed excellent hydrophilicity and organic decomposition performance. Even the film with rutile structure deposited at 145.0 nm min -1 had a contact angle of less than 2.5 deg. by UV irradiation for 5.0 h and an organics-decomposition performance index of 8.9 [μmol l -1 min -1 ] for methylene blue

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

Science.gov (United States)

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.

Heterogeneous photocatalytic degradation of toluene in static environment employing thin films of nitrogen-doped nano-titanium dioxide

Science.gov (United States)

Kannangara, Yasun Y.; Wijesena, Ruchira; Rajapakse, R. M. G.; de Silva, K. M. Nalin

2018-04-01

Photocatalytic semiconductor thin films have the ability to degrade volatile organic compounds (VOCs) causing numerous health problems. The group of VOCs called "BTEX" is abundant in houses and indoor of automobiles. Anatase phase of TiO2 has a band gap of 3.2 eV and UV radiation is required for photogeneration of electrons and holes in TiO2 particles. This band gap can be decreased significantly when TiO2 is doped with nitrogen (N-TiO2). Dopants like Pd, Cd, and Ag are hazardous to human health but N-doped TiO2 can be used in indoor pollutant remediation. In this research, N-doped TiO2 nano-powder was prepared and characterized using various analytical techniques. N-TiO2 was made in sol-gel method and triethylamine (N(CH2CH3)3) was used as the N-precursor. Modified quartz cell was used to measure the photocatalytic degradation of toluene. N-doped TiO2 nano-powder was illuminated with visible light (xenon lamp 200 W, λ = 330-800 nm, intensity = 1 Sun) to cause the degradation of VOCs present in static air. Photocatalyst was coated on a thin glass plate, using the doctor-blade method, was inserted into a quartz cell containing 2.00 µL of toluene and 35 min was allowed for evaporation/condensation equilibrium and then illuminated for 2 h. Remarkably, the highest value of efficiency 85% was observed in the 1 μm thick N-TiO2 thin film. The kinetics of photocatalytic degradation of toluene by N-TiO2 and P25-TiO2 has been compared. Surface topology was studied by varying the thickness of the N-TiO2 thin films. The surface nanostructures were analysed and studied with atomic force microscopy with various thin film thicknesses.

Studies on the Preparation of Magnetic Photocatalysts

International Nuclear Information System (INIS)

Watson, S.; Scott, J.; Beydoun, D.; Amal, R.

2005-01-01

A crystalline titanium dioxide coating was deposited onto silica insulated magnetite particles to prepare a stable magnetic photocatalyst. The direct deposition of crystalline titanium dioxide was conducted by aging dispersions of insulated magnetite particles in a titanium sol-gel precursor mixture at 60-90 deg. C. The coating process was found to be influenced by pH, alkoxide precursor concentration, aging time and reaction temperature. A mechanism for the formation of the titanium dioxide coating has been proposed. The photocatalytic performance of the prepared particles was found to be related to the preparation conditions

Antibacterial effect of hydrogen peroxide-titanium dioxide suspensions in the decontamination of rough titanium surfaces.

Science.gov (United States)

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.

Synthesis and photocatalytic activity for TiO2 nanoparticles as air purification

Directory of Open Access Journals (Sweden)

Haider Adawiya

2018-01-01

Full Text Available In the present work, titanium dioxide (TiO2 nanoparticles (NP’s were prepared using sol-gel process from Titanium Tetrachloride (TiCl4 as a precursor with calcinations at two temperatures (500 and 900 °C. The effect of calcinations temperatures on the structural, optical, morphological and Root Mean Square (roughness properties were investigated by means of Scanning Electron Microscopy, X-ray Diffraction (XRD, and Atomic Force Microscopy (AFM. Bacterial inactivation was evaluated using TiO2-coated Petri dishes. A thin layer of photocatalytic TiO2 powder was deposited on glass substrate in order to investigate the self-cleaning effect of TiO2 nanoparticles in indoor and outdoor applications. Ultra-hydrophilicity was assessed by measuring the contact angle and it evaluated photolysis properties through the degradation of potassium permanganate (KMnO4 under direct sunlight. XRD analysis indicated that the structure of TiO2 was anatase at 500 °C and rutile at 900 °C calcination temperatures. As the calcination temperature increases, the crystallinity is improved and the crystallite size becomes larger. Coated films of TiO2 made the has permeability, low water contact angle and good optical activity. These are properties essential for the application of the surface of the self-cleaning. The final results illustrate that titanium dioxide can be used in the build materials to produce coated surfaces in order to minimize air pollutants that are placed in microbiologically sensitive circumference like hospitals and the food factory.

Sealing glasses for titanium and titanium alloys

Science.gov (United States)

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).

The Photocatalytic Removal of Ortho Chlorophenol from Aqueous Solution Using Modified Fly Ash - Titanium Dioxide

Directory of Open Access Journals (Sweden)

Mohamad Malakootian

2016-05-01

Full Text Available The photocatalytic process is a useful method for the effective removal of phenolic compounds. Conducted in the spring‒summer 2013 at the Engineering Research Center for Environmental Health, Kerman University of Medical Sciences, this experimental study used a modified fly ash‒TiO2 mixture to enhance the photocatalytic removal efficiency of ortho-chlorophenol. Fly ash obatined from the Thermal Power Plant in Zarand, Kerman, was initially washed with sulfuric acid before being oxidized with potassium permanganate. The mixture of modified fly ash and TiO2 was then used for the removal of ortho-chlorophenol in the presence of UV light and the factors involved in the removal process were optimized. It was found that the ortho-chlorophenol removal efficiency recorded by the mixture of modified fly ash and TiO2 was higher than that by each of the modified fly ash or TiO2/UV alone. It was, further, observed that removal efficiency with a modified fly ash to TiO2 ratio of 3:1 rose to 98.8% under optimum conditions (i.e., pH: 2; contact time: 2 h; room temperature (29±2˚C, and a catalyst dose of 0.6 g. The ortho-chlorophenol removal efficiency in real wastewater from the Coal Wash Plant in Zarand was recorded at 88.4%. Based on the results obtained from simultaneous use of modified fly ash and TiO2, the proposed method may be recommended for industrial applications.

Absorption, Distribution and Excretion of Four Forms of Titanium Dioxide Pigment in the Rat.

Science.gov (United States)

Farrell, Thomas P; Magnuson, Berna

2017-08-01

Titanium dioxide (TiO 2 ) is a white color additive that has a long history of global approval and use in food. There is, however, considerable confusion regarding the applicability of the biological effects of novel, engineered, nano-sized forms of TiO 2 developed for nonpigmentary applications to the safety of oral exposure to food grade TiO 2 pigment. The objective of this study was to assess the absorption, distribution, and routes of excretion in rats after oral exposure to food grade TiO 2 . Four different grades of TiO 2 (200 ppm) or control (0 ppm) diets were fed to rats for 7 consecutive days, followed by control diet only for 1, 24, or 72 h. Concentrations of titanium in liver, kidney and muscle were mainly below the limit of detection (titanium above the LOD were in the range of 0.1 to 0.3 mg/kg wet weight for all groups. Whole blood concentrations of titanium were titanium was equivalent to titanium in tissues following consumption of diets containing 200 ppm food grade TiO 2 . No differences in systemic absorption of the 4 forms of TiO 2 were observed indicating that the bioavailability of TiO 2 is consistently low for the range of particle sizes and morphologies examined in this study. © 2017 Institute of Food Technologists®.

Effect of photocatalytic and hydrophobic coatings on brewery surface microorganisms.

Science.gov (United States)

Priha, O; Laakso, J; Tapani, K; Levänen, E; Kolari, M; Mäntylä, T; Storgårds, E

2011-11-01

The aim of this study was to determine whether process hygiene in the beverage industry could be improved by applying new coating techniques to process surfaces. Photocatalytic titanium dioxide (TiO(2)) and hydrophobic coatings applied to stainless steel with or without added antimicrobial compounds were studied in laboratory attachment tests and in a 15-month process study. No clear reductions in numbers of attached microbes were obtained with photocatalytic coatings, except for coatings to which silver had been added. These TiO(2)+Ag coatings reduced microbial coverage in laboratory studies and in some process samples. Hydrophobic coatings reduced the area coverage of microorganisms in 4-h laboratory studies but did not affect colony counts in laboratory or process studies. The surfaces had changed from hydrophobic into hydrophilic during the process study. The coatings did not mechanically fully withstand process conditions; part of the hydrophobic coatings had peeled off, most of the precipitated Ag had dissolved, and some of the TiO(2) coatings were damaged. In conclusion, functional coatings have potential for reducing microbial loads on beverage industry surfaces, but these coatings need further development.

Síntese, caracterização e atividade fotocatalítica de catalisadores nanoestruturados de TiO2 dopados com metais Synthesis, characterization and photocatalytic activity of nanostructured TiO2 catalysts doped with metals

Directory of Open Access Journals (Sweden)

William Leonardo da Silva

2013-01-01

Full Text Available Titanium dioxide nanostructured catalysts (nanotubes doped with different metals (silver, gold, copper, palladium and zinc were synthesized by the hydrothermal method in order to promote an increase in their photocatalytic activity under visible light. The catalysts were characterized by X-ray diffraction, diffuse reflectance spectroscopy, transmission electron microscopy and specific area and pore volume determination. The materials' photocatalytic activity was evaluated by rhodamine B decomposition in a glass batch reactor. Under UV radiation, only nanotubes doped with palladium were more active than the TiO2 P25, but the samples doped with silver, palladium and gold exhibited better results than the undoped samples under visible light.

Diphenylarsinic acid contaminated soil remediation by titanium dioxide (P25) photocatalysis: Degradation pathway, optimization of operating parameters and effects of soil properties

International Nuclear Information System (INIS)

Wang, A-nan; Teng, Ying; Hu, Xue-feng; Wu, Long-hua; Huang, Yu-juan; Luo, Yong-ming; Christie, Peter

2016-01-01

Diphenylarsinic acid (DPAA) is formed during the leakage of arsenic chemical weapons in sites and poses a high risk to biota. However, remediation methods for DPAA contaminated soils are rare. Here, the photocatalytic oxidation (PCO) process by nano-sized titanium dioxide (TiO_2) was applied to degrade DPAA in soil. The degradation pathway was firstly studied, and arsenate was identified as the final product. Then, an orthogonal array experimental design of L_9(3)"4, only 9 experiments were needed, instead of 81 experiments in a conventional one-factor-at-a-time, was used to optimize the operational parameters soil:water ratio, TiO_2 dosage, irradiation time and light intensity to increase DPAA removal efficiency. Soil:water ratio was found to have a more significant effect on DPAA removal efficiency than other properties. The optimum conditions to treat 4 g soil with a DPAA concentration of 20 mg kg"−"1 were found to be a 1:10 soil: water ratio, 40 mW cm"−"2 light intensity, 5% TiO_2 in soil, and a 3-hour irradiation time, with a removal efficiency of up to 82.7%. Furthermore, this method (except for a change in irradiation time from 3 to 1.5 h) was validated in nine different soils and the removal efficiencies ranged from 57.0 to 78.6%. Removal efficiencies were found to be negatively correlated with soil electrical conductivity, organic matter content, pH and total phosphorus content. Finally, coupled with electron spin resonance (ESR) measurement, these soil properties affected the generation of OH• by TiO_2 in soil slurry. This study suggests that TiO_2 photocatalytic oxidation is a promising treatment for removing DPAA from soil. - Highlights: • DPAA was degraded into arsenate through TiO_2 (P25) photocatalytic oxidation. • Soil/water ratio was more influential on the removal of DPAA in soil by TiO_2 (P25). • Soil properties affected the adsorption of DPAA and the generation of OH• by TiO_2.

Silica supported TiO{sub 2} nanostructures for highly efficient photocatalytic application under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Pal, A.; Jana, T.K.; Chatterjee, K., E-mail: kuntal2k@gmail.com

2016-04-15

Highlights: • Synthesis of silica–titania nanocomposite by simple and facile chemical route and characterization of the materials. • Excellent catalytic activity on organic pollutant methylene blue under the visible light irradiation. • Photocatalytic rate is much higher than commercial P25 TiO{sub 2} catalyst powder. • The higher activity is attributed to the special structure and synergistic effect of the materials which has immense application potential. - Abstract: Titanium dioxide decorated silica nanospheres have been synthesized by a simple wet chemical approach. X-ray diffraction, electron microscopy and energy dispersive X-ray analysis revealed that anatase phase of TiO{sub 2} nanostructures, with exposed {0 0 1} and {1 0 1} facets, are anchored onto the amorphous silica spheres of ∼60 nm diameter. The photocatalytic activity of the sample under visible light irradiation was examined. It is found that photocatalytic efficiency of the material is better than commercial P25 TiO{sub 2} photocatalyst and the result is attributed to the unique synergistic effect of SiO{sub 2}–TiO{sub 2} nanocomposite structure resulting enhanced charge separation and charge transfer.

Tunable top-down fabrication and functional surface coating of single-crystal titanium dioxide nanostructures and nanoparticles

NARCIS (Netherlands)

Dekker, N.H.; Ha, S.; Janissen, R.; Ussembayev, Y.; van Oene, M.M.; Solano Hermosilla, B.P.

2016-01-01

Titanium dioxide (TiO2) is a key component of diverse optical and electronic applications that exploit its exceptional material properties. In particular, the use of TiO2 in its single-crystalline phase can offer substantial advantages over its amorphous and polycrystalline phases for existing and

Effects of light irradiation on bleaching by a 3.5% hydrogen peroxide solution containing titanium dioxide

International Nuclear Information System (INIS)

Suemori, T; Kato, J; Nakazawa, T; Akashi, G; Igarashi, A; Hirai, Y; Kumagai, Y; Kurata, H

2008-01-01

A low-concentration hydrogen peroxide solution containing titanium dioxide as a photocatalyst has attracted attention as a safe office bleaching agent. In this study, the influence of different kinds of light on the bleaching effect of this agent was examined. The bleaching agent was applied to hematoporphyrin-stained paper strips that were then irradiated with a 405-nm diode laser (800 mW/cm 2 ), a halogen lamp (720 mW/cm 2 ), or an LED (835 mW/cm 2 ) for 5 minutes. The color was measured spectrophotometrically before treatment and every 30 seconds thereafter, and the effects of bleaching on the strip were assessed using the CIE 1976 L * a * b * color coordinate system. Of the three different irradiation conditions, 405-nm laser irradiation gave the strongest bleaching effect with 3.5% hydrogen peroxide containing titanium dioxide. The laser provides strong irradiance at 405 nm, which corresponds to the absorption range of the bleaching agent, and consequently the largest effect was obtained

Outstanding field emission properties of wet-processed titanium dioxide coated carbon nanotube based field emission devices

Energy Technology Data Exchange (ETDEWEB)

Xu, Jinzhuo; Ou-Yang, Wei, E-mail: ouyangwei@phy.ecnu.edu.cn; Chen, Xiaohong; Guo, Pingsheng; Piao, Xianqing; Sun, Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Xu, Peng; Wang, Miao [Department of Physics, Zhejiang University, 38 ZheDa Road, Hangzhou 310027 (China); Li, Jun [Department of Electronic Science and Technology, Tongji University, 4800 Caoan Road, Shanghai 201804 (China)

2015-02-16

Field emission devices using a wet-processed composite cathode of carbon nanotube films coated with titanium dioxide exhibit outstanding field emission characteristics, including ultralow turn on field of 0.383 V μm{sup −1} and threshold field of 0.657 V μm{sup −1} corresponding with a very high field enhancement factor of 20 000, exceptional current stability, and excellent emission uniformity. The improved field emission properties are attributed to the enhanced edge effect simultaneously with the reduced screening effect, and the lowered work function of the composite cathode. In addition, the highly stable electron emission is found due to the presence of titanium dioxide nanoparticles on the carbon nanotubes, which prohibits the cathode from the influence of ions and free radical created in the emission process as well as residual oxygen gas in the device. The high-performance solution-processed composite cathode demonstrates great potential application in vacuum electronic devices.

AC/TiO2/Rubber Composite Sheet Catalysts; Fabrication, Characterization and Photocatalytic Activities

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Sriwong Chaval

2015-01-01

Full Text Available The AC/TiO2/Rubber (ACTR composite sheets weresuccessfully fabricated by a simply mixing of fixed TiO2 suspension and natural rubber latex (60% HA contents withthe varyingamounts of activated carbon (AC suspension, followed by stirring, pouring into apetri dish mold, drying at room temperature (RT, after that taking out from a mold, reversing and drying again at RT. Then, the as-fabricated ACTR composite sheets were characterized by X-ray diffractometer (XRD, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR, energy dispersive X-ray spectroscopy (EDS and scanning electron microscopy (SEMtechniques. The photocatalytic efficiencies of all ACTR composite sheet samples were evaluated by photo degrading of methylene blue (MB dye solution under UV light irradiation. The results showed that the photocatalytic activity of ACTR sheet with10.0wt%AC loading has the highest efficiency for the photo degradation of MB dye than the other sheets. This is due to the fact that it is relatively with the synergistic effect of well-combined titanium dioxide catalyst and activated carbon adsorbent.

Ion exchange of some transition metal cations on hydrated titanium dioxide in aqueous ammonia solutions

International Nuclear Information System (INIS)

Bilewicz, A.; Narbutt, J.; Dybczynski, R.

1992-01-01

The adsorption of transition metal cations on hydrated titanium dioxide in complexing ammonia and amine solutions has been studied as a function of ammonia (amine) concentration. The relationships between the distribution coefficients and ammonia concentration as well as the effects of various amines on sorption of transition metals indicate that a coordinate bond is formed between the metal ions and the hydroxy groups of the sorbent. The distribution coefficients of silver(I) and cobalt(II), which form strong ammonia complexes in aqueous solutions, decrease with increasing concentration of ammonia already at concentrations exceeding 10 -3 *mol*dm -3 . Cations of zinc, manganese and mercury which form much weaker ammonia complexes do not exhibit any effect of ammonia concentration in the whole range investigated. In the case of sorption of macroamounts of ammonia or amine complexes of silver, the molecular sieve effect plays an important role. The differences in the affinity of hydrated titanium dioxide for ammonia solvates of various transition metal ions can serve as a tool for effective separation of these ions in ammonia solutions. (author) 10 refs.; 4 figs.; 1 tab

Titanium dioxide nanoparticles increase sensitivity in the next generation of the water flea Daphnia magna.

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Mirco Bundschuh

Full Text Available The nanoparticle industry is expected to become a trillion dollar business in the near future. Therefore, the unintentional introduction of nanoparticles into the environment is increasingly likely. However, currently applied risk-assessment practices require further adaptation to accommodate the intrinsic nature of engineered nanoparticles. Combining a chronic flow-through exposure system with subsequent acute toxicity tests for the standard test organism Daphnia magna, we found that juvenile offspring of adults that were previously exposed to titanium dioxide nanoparticles exhibit a significantly increased sensitivity to titanium dioxide nanoparticles compared with the offspring of unexposed adults, as displayed by lower 96 h-EC(50 values. This observation is particularly remarkable because adults exhibited no differences among treatments in terms of typically assessed endpoints, such as sensitivity, number of offspring, or energy reserves. Hence, the present study suggests that ecotoxicological research requires further development to include the assessment of the environmental risks of nanoparticles for the next and hence not directly exposed generation, which is currently not included in standard test protocols.

Synthesis and photocatalytic activity of ytterbium-doped titania/diatomite composite photocatalysts

International Nuclear Information System (INIS)

Tang, Wenjian; Qiu, Kehui; Zhang, Peicong; Yuan, Xiqiang

2016-01-01

Graphical abstract: - Highlights: • Yb-doped TiO_2/diatomite composite photocatalysts were prepared by a sol-gel method. • Yb-doped TiO_2/diatomite photocatalysts show much higher photocatalytic activity. • The higher photodegradation rate is due to the effect of diatomite and Yb doping. - Abstract: Ytterbium-doped titanium dioxide (Yb-TiO_2)/diatomite composite materials with different Yb concentrations were prepared by sol–gel method. The phase structure, morphology, and chemical composition of the as-prepared composites were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and ultraviolet–visible (UV–vis) diffuse reflection spectroscopy. The XRD and Raman spectroscopy analysis indicated that the TiO_2 existed in the form of pure anatase in the composites. The SEM images exhibited the well deposition and dispersion of TiO_2 nanoparticles with little agglomeration on the surfaces of diatoms. The UV–vis diffuse reflection spectra showed that the band gap of TiO_2 could be narrowed by the introduction of Yb species, which was further affected by doping concentration of Yb. The photocatalytic activity of synthesized samples was investigated by the degradation of methylene blue (MB) under UV light irradiation. It was observed that the photocatalytic degradation followed a pseudo-first-order kinetics according to the Langmuir–Hinshelwood model. Compared to TiO_2 and TiO_2/diatomite, the Yb-TiO_2/diatomite composites exhibited higher photocatalytic activity toward degradation of MB using UV light irradiation.

Synthesis and photocatalytic activity of ytterbium-doped titania/diatomite composite photocatalysts

Energy Technology Data Exchange (ETDEWEB)

Tang, Wenjian; Qiu, Kehui; Zhang, Peicong; Yuan, Xiqiang

2016-01-30

Graphical abstract: - Highlights: • Yb-doped TiO{sub 2}/diatomite composite photocatalysts were prepared by a sol-gel method. • Yb-doped TiO{sub 2}/diatomite photocatalysts show much higher photocatalytic activity. • The higher photodegradation rate is due to the effect of diatomite and Yb doping. - Abstract: Ytterbium-doped titanium dioxide (Yb-TiO{sub 2})/diatomite composite materials with different Yb concentrations were prepared by sol–gel method. The phase structure, morphology, and chemical composition of the as-prepared composites were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and ultraviolet–visible (UV–vis) diffuse reflection spectroscopy. The XRD and Raman spectroscopy analysis indicated that the TiO{sub 2} existed in the form of pure anatase in the composites. The SEM images exhibited the well deposition and dispersion of TiO{sub 2} nanoparticles with little agglomeration on the surfaces of diatoms. The UV–vis diffuse reflection spectra showed that the band gap of TiO{sub 2} could be narrowed by the introduction of Yb species, which was further affected by doping concentration of Yb. The photocatalytic activity of synthesized samples was investigated by the degradation of methylene blue (MB) under UV light irradiation. It was observed that the photocatalytic degradation followed a pseudo-first-order kinetics according to the Langmuir–Hinshelwood model. Compared to TiO{sub 2} and TiO{sub 2}/diatomite, the Yb-TiO{sub 2}/diatomite composites exhibited higher photocatalytic activity toward degradation of MB using UV light irradiation.

Ultrafine titanium dioxide particles in the absence of photoactivation can induce oxidative damage to human bronchial epithelial cells

International Nuclear Information System (INIS)

Gurr, J.-R.; Wang, Alexander S.S.; Chen, C.-H.; Jan, K.-Y.

2005-01-01

Ultrafine titanium dioxide (TiO 2 ) particles have been shown to exhibit strong cytotoxicity when exposed to UVA radiation, but are regarded as a biocompatible material in the absence of photoactivation. In contrast to this concept, the present results indicate that anatase-sized (10 and 20 nm) TiO 2 particles in the absence of photoactivation induced oxidative DNA damage, lipid peroxidation, and micronuclei formation, and increased hydrogen peroxide and nitric oxide production in BEAS-2B cells, a human bronchial epithelial cell line. However, the treatment with anatase-sized (200 and >200 nm) particles did not induce oxidative stress in the absence of light irradiation; it seems that the smaller the particle, the easier it is for the particle to induce oxidative damage. The photocatalytic activity of the anatase form of TiO 2 was reported to be higher than that of the rutile form. In contrast to this notion, the present results indicate that rutile-sized 200 nm particles induced hydrogen peroxide and oxidative DNA damage in the absence of light but the anatase-sized 200 nm particles did not. In total darkness, a slightly higher level of oxidative DNA damage was also detected with treatment using an anatase-rutile mixture than with treatment using either the anatase or rutile forms alone. These results suggest that intratracheal instillation of ultrafine TiO 2 particles may cause an inflammatory response

Growth and structure of titanium dioxide on the transition metal surfaces Re(10-10) and Ru(0001); Wachstum und Struktur von Titandioxid auf den Uebergangsmetalloberflaechen Re(10-10) und Ru(0001)

Energy Technology Data Exchange (ETDEWEB)

Rosenthal, D.

2007-03-15

In this work, we studied the growth and structure of titanium dioxide films on two morphologically different transition metal surfaces, namely the trench-like rhenium(10-10) and the hexagonal ruthenium(0001). The following methods were used: X-ray photoelectron and Auger-electron spectroscopy (XPS and AES), low energy electron diffraction (LEED), low energy Helium-ion scattering (LEIS), scanning tunneling microscopy (STM) and X-ray diffraction (XRD). Titanium dioxide films on rhenium(10-10) were synthesized by co-adsorption of titanium vapor in an oxygen atmosphere up to a thickness of 500 Aa and investigated by means of LEED, LEIS, XPS and XRD. In order to calibrate the titanium flux, the growth mode of titanium on the Re(10-10) surface was determined by means of LEIS, XPS and LEED. The growth of titanium dioxide on the hexagonal ruthenium(0001) surface was investigated by means of STM, XPS and AES. Due to the alloying affinity of Ti and Ru, a titanium oxide film pre-grown at low temperature was finally/fully oxidized at elevated temperature and pressure. First experiments concerning the growth of gold on these titanium dioxide films are presented. One important result of the ongoing work is the imaging of gold clusters with 2-5 atoms in the troughs of rutile(110) beside the typically observed clusters with 3 nm diameter by STM. (orig.)

Recent Photocatalytic Applications for Air Purification in Belgium

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Elia Boonen

2014-07-01

Full Text Available Photocatalytic concrete constitutes a promising technique to reduce a number of air contaminants such as NOx and VOC’s, especially at sites with a high level of pollution: highly trafficked canyon streets, road tunnels, the urban environment, etc. Ideally, the photocatalyst, titanium dioxide, is introduced in the top layer of the concrete pavement for best results. In addition, the combination of TiO2 with cement-based products offers some synergistic advantages, as the reaction products can be adsorbed at the surface and subsequently be washed away by rain. A first application has been studied by the Belgian Road Research Center (BRRC on the side roads of a main entrance axis in Antwerp with the installation of 10.000 m² of photocatalytic concrete paving blocks. For now however, the translation of laboratory testing towards results in situ remains critical of demonstrating the effectiveness in large scale applications. Moreover, the durability of the air cleaning characteristic with time remains challenging for application in concrete roads. From this perspective, several new trial applications have been initiated in Belgium in recent years to assess the “real life” behavior, including a field site set up in the Leopold II tunnel of Brussels and the construction of new photocatalytic pavements on industrial zones in the cities of Wijnegem and Lier (province of Antwerp. This paper first gives a short overview of the photocatalytic principle applied in concrete, to continue with some main results of the laboratory research recognizing the important parameters that come into play. In addition, some of the methods and results, obtained for the existing application in Antwerp (2005 and during the implementation of the new realizations in Wijnegem and Lier (2010–2012 and in Brussels (2011–2013, will be presented.

Adsorption and Photocatalytic Decomposition of the β-Blocker Metoprolol in Aqueous Titanium Dioxide Suspensions: Kinetics, Intermediates, and Degradation Pathways

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Violette Romero

2013-01-01

Full Text Available This study reports the photocatalytic degradation of the β-blocker metoprolol (MET using TiO2 suspended as catalyst. A series of photoexperiments were carried out by a UV lamp, emitting in the 250–400 nm range, providing information about the absorption of radiation in the photoreactor wall. The influence of the radiation wavelength on the MET photooxidation rate was investigated using a filter cutting out wavelengths shorter than 280 nm. Effects of photolysis and adsorption at different initial pH were studied to evaluate noncatalytic degradation for this pharmaceutical. MET adsorption onto titania was fitted to two-parameter Langmuir isotherm. From adsorption results it appears that the photocatalytic degradation can occur mainly on the surface of TiO2. MET removed by photocatalysis was 100% conditions within 300 min, while only 26% was achieved by photolysis at the same time. TiO2 photocatalysis degradation of MET in the first stage of the reaction followed approximately a pseudo-first-order model. The major reaction intermediates were identified by LC/MS analysis such as 3-(propan-2-ylaminopropane-1,2-diol or 3-aminoprop-1-en-2-ol. Based on the identified intermediates, a photocatalytic degradation pathway was proposed, including the cleavage of side chain and the hydroxylation addition to the parent compounds.

Titanium oxide fever

International Nuclear Information System (INIS)

De Jonge, D.; Visser, J.

2012-01-01

One measure to improve air quality is to apply photo-catalytic substances that capture NOx onto the road surface or onto baffle boards alongside the roads. The effect of titanium oxide containing clinkers with coating was discussed in the report 'Demonstration project of air-purifying pavement in Hengelo, The Netherlands' that was published in May 2011. This article examines the way in which the effectiveness of this study was determined. Can titanium oxide containing clinkers and coatings indeed capture NOx?. [nl

Disinfection of Spacecraft Potable Water Systems by Photocatalytic Oxidation Using UV-A Light Emitting Diodes

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Birmele, Michele N.; O'Neal, Jeremy A.; Roberts, Michael S.

2011-01-01

Ultraviolet (UV) light has long been used in terrestrial water treatment systems for photodisinfection and the removal of organic compounds by several processes including photoadsorption, photolysis, and photocatalytic oxidation/reduction. Despite its effectiveness for water treatment, UV has not been explored for spacecraft applications because of concerns about the safety and reliability of mercury-containing UV lamps. However, recent advances in ultraviolet light emitting diodes (UV LEDs) have enabled the utilization of nanomaterials that possess the appropriate optical properties for the manufacture of LEDs capable of producing monochromatic light at germicidal wavelengths. This report describes the testing of a commercial-off-the-shelf, high power Nichia UV-A LED (250mW A365nnJ for the excitation of titanium dioxide as a point-of-use (POD) disinfection device in a potable water system. The combination of an immobilized, high surface area photocatalyst with a UV-A LED is promising for potable water system disinfection since toxic chemicals and resupply requirements are reduced. No additional consumables like chemical biocides, absorption columns, or filters are required to disinfect and/or remove potentially toxic disinfectants from the potable water prior to use. Experiments were conducted in a static test stand consisting of a polypropylene microtiter plate containing 3mm glass balls coated with titanium dioxide. Wells filled with water were exposed to ultraviolet light from an actively-cooled UV-A LED positioned above each well and inoculated with six individual challenge microorganisms recovered from the International Space Station (ISS): Burkholderia cepacia, Cupriavidus metallidurans, Methylobacterium fujisawaense, Pseudomonas aeruginosa, Sphingomonas paucimobilis and Wautersia basilensis. Exposure to the Nichia UV-A LED with photocatalytic oxidation resulted in a complete (>7-log) reduction of each challenge bacteria population in UV-A LEDs and semi

Nanomaterial Case Studies: Nanoscale Titanium Dioxide ...

Science.gov (United States)

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 assessment approach that combines a product life cycle framework with the risk assessment paradigm. The document does not draw conclusions about potential risks. Rather, the case studies are intended to help identify what needs to be known in order to conduct a comprehensive environmental assessment of the potential risks related to nano-TiO2. This draft document is part of a process that will inform the development of EPA’s research strategy to support nanomaterial risk assessments. The complex properties of various nanomaterials make evaluating them in the abstract or with generalizations difficult if not impossible. Thus, this document focuses on two specific uses of nano-TiO2, as a drinking water treatment and as topical sunscreen. These case studies do not represent completed or even preliminary assessments; rather, they present the structure for identifying and prioritizing research needed to support future assessments.

Kinetics of photocatalytic removal of 2-amino-5-chloropyridine from water

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Abramović Biljana F.

2004-01-01

Full Text Available Titanium dioxide sensitized photocatalytic degradation of a pyridine pesticide analogue, 2-amino-5-chloropyridine, was investigated by monitoring the pyridine moiety degradation, as well as by monitoring the chloride generated in the process. Effect of the initial substrate concentration on the rate of its degradation is reported. Here we show that the kinetics of both reactions are of the zero-order in the entire investigated concentration range. The Langmuir-Hinshelwood kinetic model successfully described the influence of the initial substrate concentration on the rate of the pyridine moiety degradation. It was found that dechlorination of the substrate takes place by direct photolysis. The differences in the kinetics of pyridine moiety degradation and dechlorination were explained on the basis of the electrostatic potential for the investigated compound.

Aqueous Synthesis of Technetium-Doped Titanium Dioxide by Direct Oxidation of Titanium Powder, a Precursor for Ceramic Nuclear Waste Forms

Energy Technology Data Exchange (ETDEWEB)

Lukens, Wayne W. [Chemical; Saslow, Sarah A. [Earth

2017-11-17

Technetium-99 (Tc) is a problematic fission product that complicates the long-term disposal of nuclear waste due to its long half-life, high fission yield, and the environmental mobility of pertechnetate, its stable form in aerobic environments. One approach to preventing Tc contamination is through incorporation into durable waste forms based on weathering-resistant minerals such as rutile (titanium dioxide). Here, the incorporation of technetium into titanium dioxide by means of simple, aqueous chemistry is presented. X-ray absorption fine structure spectroscopy and diffuse reflectance spectroscopy indicate that Tc(IV) replaces Ti(IV) within the structure. Rather than being incorporated as isolated Tc(IV) ions, Tc is present as pairs of edge-sharing Tc(IV) octahedra similar to molecular Tc(IV) complexes such as [(H2EDTA)TcIV](u-O)2. Technetium-doped TiO2 was suspended in deionized water under aerobic conditions, and the Tc leached under these conditions was followed for 8 months. The normalized release rate of Tc (LRTc) from the TiO2 particles is low (3×10-6 g m-2 d-1), which illustrates the potential utility of TiO2 as waste form. However, the small size of the as-prepared TiO2 nanoparticles results in estimated retention of Tc for 104 years, which is only a fraction of the half-life of Tc (2×10-5 years).

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

Science.gov (United States)

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...

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

Science.gov (United States)

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.

Non-chapped, vertically well aligned titanium dioxide nanotubes fabricated by electrochemical etching

Science.gov (United States)

Loan Nguyen, Thu; Dieu Thuy Ung, Thi; Liem Nguyen, Quang

2014-06-01

This paper reports on the fabrication of non-chapped, vertically well aligned titanium dioxide nanotubes (TONTs) by using electrochemical etching method and further heat treatment. Very highly ordered metallic titanium nanotubes (TNTs) were formed by directly anodizing titanium foil at room temperature in an electrolyte composed of ammonium fluoride (NH4F), ethylene glycol (EG), and water. The morphology of as-formed TNTs is greatly dependent on the applied voltage, NH4F content and etching time. Particularly, we have found two interesting points related to the formation of TNTs: (i) the smooth surface without chaps of the largely etched area was dependent on the crystalline orientation of the titanium foil; and (ii) by increasing the anodizing potential from 15 V to 20 V, the internal diameter of TNT was increased from about 50 nm to 60 nm and the tube density decreased from 403 tubes μm-2 down to 339 tubes μm-2, respectively. For the anodizing duration from 1 h to 5 h, the internal diameter of each TNT was increased from ˜30 nm to 60 nm and the tube density decreased from 496 tubes μm-2 down to 403 tubes μm-2. After annealing at 400 °C in open air for 1 h, the TNTs were transformed into TONTs in anatase structure; further annealing at 600 °C showed the structural transformation from anatase to rutile as determined by Raman scattering spectroscopy.

In Vitro Cytotoxicity Assessment of an Orthodontic Composite Containing Titanium-dioxide Nano-particles

OpenAIRE

Farzin Heravi; Mohammad Ramezani; Maryam Poosti; Mohsen Hosseini; Arezoo Shajiei; Farzaneh Ahrari

2013-01-01

Background and aims. Incorporation of nano-particles to orthodontic bonding systems has been considered to prevent enamel demineralization around appliances. This study investigated cytotoxicity of Transbond XT adhesive containing 1 wt% titanium dioxide (TiO2) nano-particles. Materials and methods. Ten composite disks were prepared from each of the conventional and TiO2-containg composites and aged for 1, 3, 5, 7 and 14 days in Dulbecco’s Modified Eagle’s Medium (DMEM). The extrac...

The recovery of 99Mo from solutions of irradiated Uranium using a column with nanoparticles of Titanium Dioxide

International Nuclear Information System (INIS)

Androne, G. E.; Petre, M.; Lazar, C. G.

2016-01-01

Molyibdenum-99 (T½ = 66.02 h) decays by beta emission to 99 Tcm (T½ = 6.02 h). The latter nuclide is used in many nuclear medicine applications. The 99 Mo is produced from irradiated high (HEU) or low (LEU) enriched uranium. In this work a sensitive and selective method for recovering Mo from uranium solution, using a column with titanium dioxide nanoparticles, is developed. The titanium dioxide (TiO 2 ) nanoparticles were synthesized via sol-gel method using titanium tetra-chloride as starting material and urea as a reacting medium. A 40 ml uranium solution containing 450 g/L uranyl nitrate, 1 M HNO 3 , and 4 mg Mo was loaded on a column containing 6 g of TiO 2 sorbent at 75°C. After loading, the column was washed with 1 M HNO 3 and H 2 O. Mo was stripped from the column with 0.1 M NaOH at 25°C. The ICP-MS results indicate that 80-95% of the initial mass of Mo was loaded on the column, and 90-94% of this quantity was recovered in the strip fraction. (authors)

Risk assessment of titanium dioxide nanoparticles via oral exposure, including toxicokinetic considerations.

Science.gov (United States)

Heringa, Minne B; Geraets, Liesbeth; van Eijkeren, Jan C H; Vandebriel, Rob J; de Jong, Wim H; Oomen, Agnes G

2016-12-01

Titanium dioxide white pigment consists of particles of various sizes, from which a fraction is in the nano range (food as additive E 171 as well as in other products, such as food supplements and toothpaste. Here, we assessed whether a human health risk can be expected from oral ingestion of these titanium dioxide nanoparticles (TiO 2 NPs), based on currently available information. Human health risks were assessed using two different approaches: Approach 1, based on intake, i.e. external doses, and Approach 2, based on internal organ concentrations using a kinetic model in order to account for accumulation over time (the preferred approach). Results showed that with Approach 1, a human health risk is not expected for effects in liver and spleen, but a human health risk cannot be excluded for effects on the ovaries. When based on organ concentrations by including the toxicokinetics of TiO 2 NPs (Approach 2), a potential risk for liver, ovaries and testes is found. This difference between the two approaches shows the importance of including toxicokinetic information. The currently estimated risk can be influenced by factors such as absorption, form of TiO 2 , particle fraction, particle size and physico-chemical properties in relation to toxicity, among others. Analysis of actual particle concentrations in human organs, as well as organ concentrations and effects in liver and the reproductive system after chronic exposure to well-characterized TiO 2 (NPs) in animals are recommended to refine this assessment.

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

Science.gov (United States)

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.

Evaluation of photocatalytic treatment of industrial wastewater using solar energy

International Nuclear Information System (INIS)

Restrepo, Gloria Maria; Rios, Luis A; Marin, Juan Miguel; Montoya, Juan Felipe; Velasquez, Jorge Armando

2008-01-01

Wastewater of a chemical industry was treated in a photocatalytic process, using a solar photo-reactor made of glass corrugated flat plates that had been set in cascade and using Titanium Dioxide (Degussa p-25) as photocatalyst that is supported on each one of them in film form. the influence of three variables in the decontamination efficiency were studied: amount of H 2 O 2 , volume of water and amount of dispersed TiO 2 , by means of the accomplishment of fifteen experiments carried out in discontinuous operation mode by a period of 5 hours for each test. The obtained results allow establishing that the FH is a viable technology of treatment like previous stage to a biological treatment since percentage of reduction in the DQO varies between 6 and 46% and was managed to reach a biodegradable effluent in all tests

Decomposition of NO in gas phase by gold nanoparticles supported on titanium dioxide synthesized by the deposition-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Hernandez-Fernandez, J., E-mail: javier.fernandez@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados, Av. Miguel de Cervantes 120, Complejo Industrial C.P. 31109, Chihuahua, Chih. (Mexico); Instituto Mexicano del Petroleo, Direccion de Investigacion y Posgrado, Eje Central Lazaro Cardenas 152, C.P. 07730, D.F. (Mexico); Zanella, R. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, UNAM, Circuito exterior S/N, Ciudad Universitaria, C.P. 04510, A.P. 70-186, Delegacion Coyoacan, D.F. (Mexico); Aguilar-Elguezabal, A. [Centro de Investigacion en Materiales Avanzados, Av. Miguel de Cervantes 120, Complejo Industrial C.P. 31109, Chihuahua, Chih. (Mexico); Arizabalo, R.D.; Castillo, S.; Moran-Pineda, M. [Instituto Mexicano del Petroleo, Direccion de Investigacion y Posgrado, Eje Central Lazaro Cardenas 152, C.P. 07730, D.F. (Mexico)

2010-10-25

In the present work, the synthesis, characterization and photoactivity concerning the nitrogen monoxide (NO) decomposition of sol-gel Au/TiO{sub 2} photocatalysts are reported. TiO{sub 2} was prepared by gelling titanium (IV) isopropoxide, and gold nanoparticles were added by the deposition-precipitation method with urea. The catalysts with different gold concentrations were characterized by the following techniques: BET, XRD, UV-vis and dark-field TEM. It was found that by using this synthesis method, a high dispersion of gold nanoparticles on TiO{sub 2} was reached (4.4-6.7 nm), and the obtained structure lead to a band gap energy that is lower than the one observed for undoped TiO{sub 2}. A NO + O{sub 2} mixture (150 ppm) was used to evaluate the photocatalytic activity in situ, at room temperature, under atmospheric pressure and a UV lamp was used as radiation source. The photocatalytic conversion of nitrogen monoxide (NO) was followed by FTIR, which reached 96% in 60 min. The Au/TiO{sub 2} materials showed an enhanced photocatalytic activity when compared with the reference TiO{sub 2}.

Influence of visible-light irradiation on physicochemical and photocatalytic properties of nitrogen-doped three-dimensional (3D) titanium dioxide

International Nuclear Information System (INIS)

Lee, Hyun Uk; Lee, Soon Chang; Choi, Saehae; Son, Byoungchul; Kim, Hyeran; Lee, Sang Moon; Kim, Hae Jin; Lee, Jouhahn

2013-01-01

Highlights: • The N-3D TiO 2 was synthesized at low temperature via a modified hydrothermal process and ultrasound irradiation. • The N-3D TiO 2 is irradiated with visible-light (*N-3D TiO 2 ) to improve the hydroxylation of its surface. • The N- and *N-3D TiO 2 exhibited excellent photocatalytic and antibacterial activities. • Moreover, the *N-3D TiO 2 exhibits excellent photocatalytic stability. -- Abstract: We report highly active visible-light driven nitrogen-doped three-dimensional polycrystalline anatase TiO 2 photocatalysts (N-3D TiO 2 ) for environmental and biomedical applications. N-3D TiO 2 is synthesized at a low temperature ( 2 is additionally irradiated with visible-light to improve the hydroxylation of its surface. Under visible-light irradiation, the photocatalytic activity of visible-light irradiated N-3D TiO 2 (*N-3D TiO 2 ; [k] = 1.435 h −1 ) is 26.1 times higher than that of 3D TiO 2 ([k] = 0.055 h −1 ). The *N-3D TiO 2 is highly recyclable and retained 91.8% of the initial decolorization rate after fifteen cycles. Interestingly, the *N-3D TiO 2 shows very strong antibacterial properties against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) after exposure to visible-light for 3 h. The antibacterial properties of *N-3D TiO 2 are more effective than those of TiO 2 , 3D TiO 2 , and N-3D TiO 2 . More than 91.3% of the E. coli is sterilized after ten cycles. There are a large increase in the photocatalytic and antibacterial activity of *N-3D TiO 2 relative to that of N-3D TiO 2 owing to the hydroxylation of the N-3D TiO 2 surface as a result of the visible-light irradiation. These results indicate that *N-3D TiO 2 might have utility in several promising applications such as highly efficient water/air treatment, inactivation of pathogenic microorganisms, and solar-energy conversion

Development and characterization of multilayer films of polyaniline, titanium dioxide and CTAB for potential antimicrobial applications.

Science.gov (United States)

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.

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

Science.gov (United States)

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...

Photocatalytic degradation of p-phenylenediamine with TiO{sub 2}-coated magnetic PMMA microspheres in an aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Chen, Y.-H. [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Chung-Hsiao E. Road, Taipei 106, Taiwan (China)], E-mail: yhchen1@ntu.edu.tw; Liu, Y.-Y.; Lin, R.-H.; Yen, F.-S. [Department of Chemical and Material Engineering, National Kaohsiung University of Applied Sciences, 415 Chien Kung Road, Kaohsiung 807, Taiwan (China)

2009-04-30

This study investigates the photocatalytic degradation of p-phenylenediamine (PPD) with titanium dioxide-coated magnetic poly(methyl methacrylate) (TiO{sub 2}/mPMMA) microspheres. The TiO{sub 2}/mPMMA microspheres are employed as novel photocatalysts with the advantages of high photocatalytic activity, magnetic separability, and good durability. The scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and transmission electron microscopy (TEM) images of the TiO{sub 2}/mPMMA microspheres are used to characterize the morphology, element content, and distribution patterns of magnetite and TiO{sub 2} nanoparticles. The BET-specific surface area and saturation magnetization of the TiO{sub 2}/mPMMA microspheres are observed as 2.21 m{sup 2}/g and 4.81 emu/g, respectively. The photocatalytic degradation of PPD are performed under various experimental conditions to examine the effects of initial PPD concentration, TiO{sub 2}/mPMMA microsphere dosage, and illumination condition on the eliminations of PPD and chemical oxygen demand (COD) concentrations. Good repeatability of photocatalytic performance with the use of the TiO{sub 2}/mPMMA microspheres has been demonstrated in the multi-run experiments. The photocatalytic kinetics for the reductions of PPD and COD associated with the initial PPD concentration, UV radiation intensity, and TiO{sub 2}/mPMMA microsphere dosage are proposed. The relationships between the reduction percentages of COD and PPD are clearly presented.

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.

Directory of Open Access Journals (Sweden)

Sarah Triboulet

Full Text Available 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.

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.

Science.gov (United States)

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.

Titanium pigmentation. An electron probe microanalysis study

International Nuclear Information System (INIS)

Dupre, A.; Touron, P.; Daste, J.; Lassere, J.; Bonafe, J.L.; Viraben, R.

1985-01-01

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

Real time, in situ observation of the photocatalytic inactivation of Saccharomyces cerevisiae cells

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jingtao [School of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Environment Functional Materials Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Xiaoxin [Environment Functional Materials Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Qi, E-mail: qili@imr.ac.cn [Environment Functional Materials Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Shang, Jian Ku [Environment Functional Materials Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2015-04-01

An in situ microscopy technique was developed to observe in real time the photocatalytic inactivation process of Saccharomyces cerevisiae (S. cerevisiae) cells by palladium-modified nitrogen-doped titanium oxide (TiON/PdO) under visible light illumination. The technique was based on building a photocatalytic micro-reactor on the sample stage of a fluorescence/phase contrast microscopy capable of simultaneously providing the optical excitation to activate the photocatalyst in the micro-reactor and the illumination to acquire phase contrast images of the cells undergoing the photocatalytic inactivation process. Using TiON/PdO as an example, the technique revealed for the first time the vacuolar activities inside S. cerevisiae cells subjected to a visible light photocatalytic inactivation. The vacuoles responded to the photocatalytic attack by the first expansion of the vacuolar volume and then contraction, before the vacuole disappeared and the cell structure collapsed. Consistent with the aggregate behavior observed from the cell culture experiments, the transition in the vacuolar volume provided clear evidence that photocatalytic disinfection of S. cerevisiae cells started with an initiation period in which cells struggled to offset the photocatalytic damage and moved rapidly after the photocatalytic damage overwhelmed the defense mechanisms of the cells against oxidative attack. - Highlights: • Palladium-modified nitrogen-doped titanium oxidephotocatalyst (TiON/PdO) • Effective visible-light photocatalytic disinfection of yeast cells by TiON/PdO • Real time, in situ observation technique was developed for photocatalytic disinfection. • The fluorescence/phase contrast microscope with a photocatalytic micro-reactor • Yeast cell disinfection happened before the cell structure collapsed.

Characterization of thin TiO2 films prepared by plasma enhanced chemical vapour deposition for optical and photocatalytic applications

International Nuclear Information System (INIS)

Sobczyk-Guzenda, A.; Gazicki-Lipman, M.; Szymanowski, H.; Kowalski, J.; Wojciechowski, P.; Halamus, T.; Tracz, A.

2009-01-01

Thin titanium oxide films were deposited using a radio frequency (RF) plasma enhanced chemical vapour deposition method. Their optical properties and thickness were determined by means of ultraviolet-visible absorption spectrophotometry. Films of the optical parameters very close to those of titanium dioxide have been obtained at the high RF power input. Their optical quality is high enough to allow for their use in a construction of stack interference optical filters. At the same time, these materials exhibit strong photocatalytic effects. The results of structural analysis, carried out by Raman Shift Spectroscopy, show that the coatings posses amorphous structure. However, Raman spectra of the same films subjected to thermal annealing at 450 o C disclose an appearance of a crystalline form, namely that of anatase. Surface morphology of the films has also been characterized by Atomic Force Microscopy revealing granular, broccoli-like topography of the films.

Comparison of the antifungal activity of titanium dioxide based nanosilver packaging and conventional polyethylene packaging in consumed bread

Directory of Open Access Journals (Sweden)

H Mohammadi

2014-12-01

Full Text Available Using titanium dioxide nanosilver packaging which is antibacterial and resistance to the diffusion of gases such as oxygen is increasing in food industry. Therefore we compared the effect of titanium dioxide based nanosilver packaging and conventional polyethylene packaging - on fungal flora of consuming bread in order to increase the shelf life storage of  consuming bread. One hundred forty four samples of 6 different types of loaf of bread randomly obtained from 12 bakeries in District 2 of Tehran. The samples were packaged with 3%, 5% and 10% nano coatings and also conventional polyethylene coatings as control group. The bacterial examination and monitoring of samples, according to the national standards of Iran was carried out 3 times, on days 1, 3, 7, 14 and 28, of study period.This study showed that the film type and storage period, were main factors which significantly influenced fungal flora of bread. The lowest rate of various fungi growth (%14 was observed in 10% Nano film, while the highest rate of various fungi growth (47% was observed in conventional polyethylene coating (P<0.001. With increasing storage periods,  the number of various fungi increased, however this correlation was not similar in most of breads and fungi types. There were significant difference between them (P = 0.001. According to the results of the present study, due to increasing population growth and in order to improve food security, using packages with nanosilver particles which are based on titanium dioxide, prevails over the polyethylene packages. Therefore using such packages are highly recommended in bakery industry.

The Influence of Various Deposition Techniques on the Photoelectrochemical Properties of the Titanium Dioxide Thin Fil

Czech Academy of Sciences Publication Activity Database

Morozová, Magdalena; Klusoň, Petr; Dzik, P.; Veselý, M.; Baudyš, M.; Krýsa, J.; Šolcová, Olga

2013-01-01

Roč. 65, č. 3 (2013), s. 452-458 ISSN 0928-0707 R&D Projects: GA TA ČR TA01020804 Grant - others:GA ČR(CZ) GP104/09/P165 Institutional support: RVO:67985858 Keywords : titanium dioxide * photoelectrochemical properties * deposition techniques Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.547, year: 2013

Temperature dependent optical characterization of Ni-TiO2 thin films as potential photocatalytic material

Science.gov (United States)

De, Rajnarayan; Haque, S. Maidul; Tripathi, S.; Rao, K. Divakar; Singh, Ranveer; Som, T.; Sahoo, N. K.

2017-09-01

Along with other transition metal doped titanium dioxide materials, Ni-TiO2 is considered to be one of the most efficient materials for catalytic applications due to its suitable energy band positions in the electronic structure. The present manuscript explores the possibility of improving the photocatalytic activity of RF magnetron sputtered Ni-TiO2 films upon heat treatment. Optical, structural and morphological and photocatalytic properties of the films have been investigated in detail for as deposited and heat treated samples. Evolution of refractive index (RI) and total film thickness as estimated from spectroscopic ellipsometry characterization are found to be in agreement with the trend in density and total film thickness estimated from grazing incidence X-ray reflectivity measurement. Interestingly, the evolution of these macroscopic properties were found to be correlated with the corresponding microstructural modifications realized in terms of anatase to rutile phase transformation and appearance of a secondary phase namely NiTiO3 at high temperature. Corresponding morphological properties of the films were also found to be temperature dependent which leads to modifications in the grain structure. An appreciable reduction of optical band gap from 2.9 to 2.5 eV of Ni-TiO2 thin films was also observed as a result of post deposition heat treatment. Testing of photocatalytic activity of the films performed under UV illumination demonstrates heat treatment under atmospheric ambience to be an effective means to enhance the photocatalytic efficiency of transition metal doped titania samples.

The effects of titanium dioxide coatings on light-derived heating and transdermal heat transfer in bovine skin

NARCIS (Netherlands)

Bartle, S J; Thomson, D U; Gehring, R; van der Merwe, B. D.

2017-01-01

The effects of titanium dioxide coatings of bovine hides on light absorption and transdermal transfer of light-derived heat were investigated. Four hair-on rug hides from Holstein cattle were purchased. Twelve samples about 20 cm on a side were cut from each hide; nine from the black-colored areas,

Photocatalytic and chemical oxidation of organic compounds in supercritical carbon dioxide. Progress report for FY97

International Nuclear Information System (INIS)

Blake, D.M.; Bryant, D.L.; Reinsch, V.

1997-01-01

'The background for the project is briefly reviewed and the work done during the nine months since funding was received is documented. Work began in January, 1997. A post doctoral fellow joined the team in April. The major activities completed this fiscal year were: staffing the project, design of the experimental system, procurement of components, assembly of the system. preparation of the Safe Operating Procedure and ES and H compliance, pressure testing, establishing data collection and storage methodology, and catalyst preparation. Objective The objective of the project is to develop new chemistry for the removal of organic contaminants from supercritical carbon dioxide. This has application in processes used for continuous cleaning and extraction of parts and waste materials. A secondary objective is to increase the fundamental understanding of photocatalytic chemistry. Cleaning and extraction using supercritical carbon dioxide (scCO 2 ) can be applied to the solution of a wide range of environmental and pollution prevention problems in the DOE complex. Work is being done that explores scCO 2 in applications ranging from cleaning contaminated soil to cleaning components constructed from plutonium. The rationale for use of scCO 2 are based on the benign nature, availability and low cost, attractive solvent properties, and energy efficient separation of the extracted solute from the solvent by moderate temperature or pressure changes. To date, R and D has focussed on the methods and applications of the extraction steps of the process. Little has been done that addresses methods to polish the scCO 2 for recycle in the cleaning or extraction operations. In many applications it will be desirable to reduce the level of contamination from that which would occur at steady state operation of a process. This proposal addresses chemistry to achieve that. This would be an alternative to removing a fraction of the contaminated scCO 2 for disposal and using makeup scCO 2

Photocatalytic and chemical oxidation of organic compounds in supercritical carbon dioxide. Progress report for FY97

Energy Technology Data Exchange (ETDEWEB)

Blake, D.M.; Bryant, D.L.; Reinsch, V.

1997-09-30

'The background for the project is briefly reviewed and the work done during the nine months since funding was received is documented. Work began in January, 1997. A post doctoral fellow joined the team in April. The major activities completed this fiscal year were: staffing the project, design of the experimental system, procurement of components, assembly of the system. preparation of the Safe Operating Procedure and ES and H compliance, pressure testing, establishing data collection and storage methodology, and catalyst preparation. Objective The objective of the project is to develop new chemistry for the removal of organic contaminants from supercritical carbon dioxide. This has application in processes used for continuous cleaning and extraction of parts and waste materials. A secondary objective is to increase the fundamental understanding of photocatalytic chemistry. Cleaning and extraction using supercritical carbon dioxide (scCO{sub 2}) can be applied to the solution of a wide range of environmental and pollution prevention problems in the DOE complex. Work is being done that explores scCO{sub 2} in applications ranging from cleaning contaminated soil to cleaning components constructed from plutonium. The rationale for use of scCO{sub 2} are based on the benign nature, availability and low cost, attractive solvent properties, and energy efficient separation of the extracted solute from the solvent by moderate temperature or pressure changes. To date, R and D has focussed on the methods and applications of the extraction steps of the process. Little has been done that addresses methods to polish the scCO{sub 2} for recycle in the cleaning or extraction operations. In many applications it will be desirable to reduce the level of contamination from that which would occur at steady state operation of a process. This proposal addresses chemistry to achieve that. This would be an alternative to removing a fraction of the contaminated scCO{sub 2} for

Functionalization of nanoparticle titanium dioxide with different bifunctional organic molecules and trimers of transition compounds for obtaining new materials

International Nuclear Information System (INIS)

Rivera Martinez, Maria Cinthya

2012-01-01

Functionalization of titanium dioxide in nanoporous anatase phase is investigated for obtaining new nanomaterials. Functionalizations were performed using two heating methods: the conventional of refluxing heating method and microwave irradiation with bifunctional organic molecules is used to study how to anchor molecules and the change in the wettability of the material. Besides, reactions with organic molecules were performed as the derived from nanoproxene. The growth layer by layer is performed using the bifunctional molecules previous for the immobilization of cobalt trimers. Functionalized molecules were characterized by infrared spectroscopy, X-ray diffraction, contact angle, scanning electron microscopy, x-ray elemental analysis, plasma atomic emission spectroscopy coupled inductively, x-ray photoelectron spectroscopy and thermogravimetric analysis. This type of functionalizations on nanoporous titanium dioxide could potentially improve optical sensitivity and activity of this nanomaterial in the visible region. (author) [es

Titanium dioxide-based DGT technique for in situ measurement of dissolved reactive phosphorus in fresh and marine waters

DEFF Research Database (Denmark)

Panther, Jared G.; Teasdale, Peter R.; Bennett, William W.

2010-01-01

A new diffusive gradients in a thin film (DGT) technique for measuring dissolved reactive phosphorus (DRP) in fresh and marine waters is reported. The new method, which uses a commercially available titanium dioxide based adsorbent (Metsorb), was evaluated and compared to the well-established fer...

Evaluation of a titanium dioxide-based DGT technique for measuring inorganic uranium species in fresh and marine waters

DEFF Research Database (Denmark)

Hutchins, Colin M.; Panther, Jared G.; Teasdale, Peter R.

2012-01-01

A new diffusive gradients in a thin film (DGT) technique for measuring dissolved uranium (U) in freshwater is reported. The new method utilises a previously described binding phase, Metsorb (a titanium dioxide based adsorbent). This binding phase was evaluated and compared to the well-established...

Adsorption of polymethacrylic acid from aqueous solutions on disperse titanium dioxide

Science.gov (United States)

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.

Analysis of X-ray diffraction of the titanium dioxide (TiO{sub 2}) synthesized by the Pechini Method for application in heterogeneous photocatalysis processes; Analise de difracao de raios X do dioxido de titanio (TiO{sub 2}) sintetizado pelo metodo Pechini para aplicacao em processos de fotocatalise heterogenea

Energy Technology Data Exchange (ETDEWEB)

Oliveira, P.L.; Araujo, D.S.; Costa, A.C.F.M.; Oliveira, L.S.C., E-mail: palomalima_eq@yahoo.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

2016-07-01

Titanium dioxide (TiO{sub 2}) is a polymorph commonly applied to heterogeneous photocatalysis processes for being relatively inexpensive and photo - stable. It is usually found in three different crystalline phases (anatase, rutile and brookite), which directly interfere in their photocatalytic efficiency. Therefore, this study aimed to investigate the obtainment of TiO{sub 2} by Pechini method in different conditions for application in the heterogeneous photocatalysis process. For this purpose, it was evaluated by analysis of X-ray diffraction (XRD ) the behavior of TiO{sub 2} materials synthesized in proportions of 2:1 and 3:1 (titanium isopropoxide/citric acid), pyrolyzed at 300°C/3h and 400°C /h and calcined at 400°C and 500°C/1h. The results revealed that the TiO{sub 2} samples produced in the ratio of 2:1 and 3:1 isopropoxide/citric acid and calcined at 500°C/h presented the best results. (author)

Titanium photocatalyst against human pathogenic microorganisms

International Nuclear Information System (INIS)

Kussovski, V.; Stefchev, P.; Kirilov, R.

2011-01-01

The conventional methods of disinfection are not effective in the longer term. They are time and staff intensive and use aggressive chemicals. Photocatalytic oxidation on surfaces coated with titanium dioxide (TiO 2 ) might offer a possible alternative. The antimicrobial activity of TiO 2 powder P25 and thin films of TiO 2 on glass slides against representative strains of microorganisms associated with hospital-acquired infections (Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans) was investigated in vitro. High efficiency has been found in the case of the studied bacterial strains, particularly for the P. aeruginosa. It was shown that it is possible to disinfect surfaces coated with TiO 2 and stimulated by UV-A light. The reduction efficiencies for P. aeruginosa, S. aureus and C. albicans were 3.19, 2.32 and 1.22. In all cases sublethal UV-A doses provoked an important lethality in the presence of TiO 2 . (authors)

Photocatalysis applied to concrete products - Part 1: Principles and test procedure

NARCIS (Netherlands)

Hunger, M.; Hüsken, G.; Brouwers, H.J.H.

2008-01-01

This three-part article addresses the photocatalytic properties of concrete containing titanium dioxide (TiO2). In the first part, the evaluation of the air purifying abilities of the final concrete product is described. A setup for measuring the performance of photocatalytic active concrete

Modified surface of titanium dioxide nanoparticles-based biosensor for DNA detection

Science.gov (United States)

Nadzirah, Sh.; Hashim, U.; Rusop, M.

2018-05-01

A new technique was used to develop a simple and selective picoammeter DNA biosensor for identification of E. coli O157:H7. This biosensor was fabricated from titanium dioxide nanoparticles that was synthesized by sol-gel method and spin-coated on silicon dioxide substrate via spinner. 3-Aminopropyl triethoxy silane (APTES) was used to modify the surface of TiO2. Simple surface modification approach has been applied; which is single dropping of APTES onto the TiO2 nanoparticles surface. Carboxyl modified probe DNA has been bind onto the surface of APTES/TiO2 without any amplifier element. Electrical signal has been used as the indicator to differentiate each step (surface modification of TiO2 and probe DNA immobilization). The I-V measurements indicate extremely low current (pico-ampere) flow through the device which is 2.8138E-10 A for pure TiO2 nanoparticles, 2.8124E-10 A after APTES modification and 3.5949E-10 A after probe DNA immobilization.

Influence of the peroxide group on the surface of titanium dioxide synthesized by the OPM route

International Nuclear Information System (INIS)

Santos, Estela Melare Ribeiro dos; Kubo, Andressa Mayumi; Gorup, Luiz Fernando; Francatto, Patricia; Souza Neto, Francisco Nunes de; Leite, Edson Roberto; Longo, Elson; Camargo, Emerson Rodrigues

2016-01-01

Full text: In the context of nanotechnology, there is a growing demand for environmentally sustainable solutions and technological innovations that are linked to reducing energy consumption and minimizing waste generation during the synthesis process. The Oxidant Peroxide Method for titanium dioxide synthesis (TiO 2 -OPM) is based on the oxidation of titanium ions to obtain nanometric powders that are highly reactive particles with controlled morphology. This method is easy and advantageous because it uses reagents of low toxicity, without the necessity to operate in inert atmosphere and at high temperatures. In this work, we obtained nanometric powders of TiO 2 -OPM from metallic titanium (TiO 2 -Met), and titanium isopropoxide (TiO 2 -Iso). Separately, the precursors reacts with hydrogen peroxide in ammoniacal medium in order to compare their reactivity by quantifying the peroxo groups on the surface. Scanning electronic microscopy (SEM) images showed nanoparticles of 10nm of both materials. X-ray diffraction (XRD) patterns showed typical structures of crystalline materials with mixture of anatase and rutile phase of titanium dioxide. Raman spectroscopy also cooperated with the XRD patterns showing vibrational modes of the mixture of phases (anatase and rutile) in both materials. Thermogravimetric analysis (TGA) showed that the two materials lost mass, in which in the first stage (80 - 125 deg C) occurred 24% of loss and in the second stage (235-265 deg C) is between 10% - 13%, and is related to the elimination of peroxo groups at the surface due to thermal treatment. Differential scanning calorimetry (DSC) revealed peaks related to exothermic decomposition of the peroxo groups (200 - 250 deg C) that coincided with peak rates of mass loss in the TGA. And the redox titration showed that the surface of the TiO 2 -Met had peroxo groups in 8.6 % w/w and 10.1 % w/w for TiO 2 -Iso, resulting in an increase of peroxo groups on the surface, making the TiO 2 -Iso route

Influence of the peroxide group on the surface of titanium dioxide synthesized by the OPM route

Energy Technology Data Exchange (ETDEWEB)

Santos, Estela Melare Ribeiro dos; Kubo, Andressa Mayumi; Gorup, Luiz Fernando; Francatto, Patricia; Souza Neto, Francisco Nunes de; Leite, Edson Roberto; Longo, Elson; Camargo, Emerson Rodrigues, E-mail: estelamelare@yahoo.com.br [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

2016-07-01

Full text: In the context of nanotechnology, there is a growing demand for environmentally sustainable solutions and technological innovations that are linked to reducing energy consumption and minimizing waste generation during the synthesis process. The Oxidant Peroxide Method for titanium dioxide synthesis (TiO{sub 2}-OPM) is based on the oxidation of titanium ions to obtain nanometric powders that are highly reactive particles with controlled morphology. This method is easy and advantageous because it uses reagents of low toxicity, without the necessity to operate in inert atmosphere and at high temperatures. In this work, we obtained nanometric powders of TiO{sub 2}-OPM from metallic titanium (TiO{sub 2}-Met), and titanium isopropoxide (TiO{sub 2}-Iso). Separately, the precursors reacts with hydrogen peroxide in ammoniacal medium in order to compare their reactivity by quantifying the peroxo groups on the surface. Scanning electronic microscopy (SEM) images showed nanoparticles of 10nm of both materials. X-ray diffraction (XRD) patterns showed typical structures of crystalline materials with mixture of anatase and rutile phase of titanium dioxide. Raman spectroscopy also cooperated with the XRD patterns showing vibrational modes of the mixture of phases (anatase and rutile) in both materials. Thermogravimetric analysis (TGA) showed that the two materials lost mass, in which in the first stage (80 - 125 deg C) occurred 24% of loss and in the second stage (235-265 deg C) is between 10% - 13%, and is related to the elimination of peroxo groups at the surface due to thermal treatment. Differential scanning calorimetry (DSC) revealed peaks related to exothermic decomposition of the peroxo groups (200 - 250 deg C) that coincided with peak rates of mass loss in the TGA. And the redox titration showed that the surface of the TiO{sub 2}-Met had peroxo groups in 8.6 % w/w and 10.1 % w/w for TiO{sub 2}-Iso, resulting in an increase of peroxo groups on the surface, making

Visible Light-Photocatalytic Activity of Sulfate-Doped Titanium Dioxide Prepared by the Sol−Gel Method

Directory of Open Access Journals (Sweden)

Tsuneo Fujii

2013-04-01

Full Text Available Sulfate-doped TiO2 was prepared from sol−gel systems containing titaniumalkoxide and sulfuric acid. The time needed for gelation of the systems was significantlyreduced by ultrasonic irradiation. The doped sulfate was observed by FTIR and XPSmeasurements. Some sulfate ions remained in the TiO2 even after heating at 300−600 °C.The UV and visible photocatalytic activities of the samples were confirmed by thedegradation of trichloroethylene (TCE. The activity of the photocatalyst samples duringthe UV irradiation strongly depended on their crystallinities rather than their specificsurface areas, i.e., adsorption ability. The degradation rate during the visible irradiationdepended on both the adsorption ability and visible absorption of the photocatalystsamples. The visible absorption induced by the sulfate-doping was effective for theTCE degradation.

Highly selective enrichment of phosphorylated peptides using titanium dioxide

DEFF Research Database (Denmark)

Thingholm, Tine; Jørgensen, Thomas J D; Jensen, Ole N

2006-01-01

-column. Although phosphopeptide enrichment can be achieved by using TFA and acetonitrile alone, the selectivity is dramatically enhanced by adding DHB or phthalic acid since these compounds, in conjunction with the low pH caused by TFA, prevent binding of nonphosphorylated peptides to TiO2. Using an alkaline...... a protocol for selective phosphopeptide enrichment using titanium dioxide (TiO2) chromatography. The selectivity toward phosphopeptides is obtained by loading the sample in a 2,5-dihydroxybenzoic acid (DHB) or phthalic acid solution containing acetonitrile and trifluoroacetic acid (TFA) onto a TiO2 micro...... solution (pH > or = 10.5) both monophosphorylated and multiphosphorylated peptides are eluted from the TiO2 beads. This highly efficient method for purification of phosphopeptides is well suited for the characterization of phosphoproteins from both in vitro and in vivo studies in combination with mass...

Dermal Titanium Dioxide Deposition Associated With Intralesional Triamcinolone Injection.