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Photocatalytic Water Treatment by Titanium Dioxide: Recent Updates  [PDF]
Manoj A. Lazar,Shaji Varghese,Santhosh S. Nair
Catalysts , 2012, DOI: 10.3390/catal2040572
Abstract: Photocatalytic water treatment using nanocrystalline titanium dioxide (NTO) is a well-known advanced oxidation process (AOP) for environmental remediation. With the in situ generation of electron-hole pairs upon irradiation with light, NTO can mineralize a wide range of organic compounds into harmless end products such as carbon dioxide, water, and inorganic ions. Photocatalytic degradation kinetics of pollutants by NTO is a topic of debate and the mostly reporting Langmuir-Hinshelwood kinetics must accompanied with proper experimental evidences. Different NTO morphologies or surface treatments on NTO can increase the photocatalytic efficiency in degradation reactions. Wisely designed photocatalytic reactors can decrease energy consumption or can avoid post-separation stages in photocatalytic water treatment processes. Doping NTO with metals or non-metals can reduce the band gap of the doped catalyst, enabling light absorption in the visible region. Coupling NTO photocatalysis with other water-treatment technologies can be more beneficial, especially in large-scale treatments. This review describes recent developments in the field of photocatalytic water treatment using NTO.
Photocatalytic Water Treatment by Titanium Dioxide: Recent Updates  [PDF]
Manoj A. Lazar,Shaji Varghese,Santhosh S. Nair
Catalysts , 2012, DOI: 10.3390/catal2040572
Abstract: Photocatalytic water treatment using nanocrystalline titanium dioxide (NTO) is a well-known advanced oxidation process (AOP) for environmental remediation. With the in situ generation of electron-hole pairs upon irradiation with light, NTO can mineralize a wide range of organic compounds into harmless end products such as carbon dioxide, water, and inorganic ions. Photocatalytic degradation kinetics of pollutants by NTO is a topic of debate and the mostly reporting Langmuir-Hinshelwood kinetics must accompanied with proper experimental evidences. Different NTO morphologies or surface treatments on NTO can increase the photocatalytic efficiency in degradation reactions. Wisely designed photocatalytic reactors can decrease energy consumption or can avoid post-separation stages in photocatalytic water treatment processes. Doping NTO with metals or non-metals can reduce the band gap of the doped catalyst, enabling light absorption in the visible region. Coupling NTO photocatalysis with other water-treatment technologies can be more beneficial, especially in large-scale treatments. This review describes recent developments in the field of photocatalytic water treatment using NTO.
Photocatalytic Activity of Nanostructured Titanium Dioxide Thin Films  [PDF]
Zdenek Michalcik,Marta Horakova,Petr Spatenka,Sarka Klementova,Martin Zlamal,Nicolas Martin
International Journal of Photoenergy , 2012, DOI: 10.1155/2012/689154
Abstract: 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. 1. Introduction Titanium dioxide is one of the most investigated materials in the last decades. Three forms of TiO2 can be found in nature: anatase, rutile, and brookite. Its properties like a high refractive index, chemical and mechanical stability, and/or photocatalytic activity [1–3] predetermine this material for a wide range of applications. One of the most attractive areas concerning titanium dioxide is its photocatalytic activity. The photocatalytic effect of TiO2 material is based on generation of electron-hole pairs due to the UV irradiation of TiO2. The generated pairs diffuse to the surface of the material and participate in the surface reaction leading to the decomposition of adsorbed matter [2]. A lot of articles have been published about the relation between the thin-film structure and the photocatalytic activity [4–6]. Generally, the presence of anatase or its mixture with rutile has been reported as an assumption for the photocatalytic activity of titanium dioxide films. The rutile acts as an antenna extending the photoactivity into visible wavelengths, and the structural arrangement of the similarly sized TiO2 crystallites creates catalytic “hot spots” at the rutile-anatase interface [7–10]. One of the most important factors affecting the photocatalytic efficiency is the lifetime of the electron/hole pairs. The excitons generated during the UV irradiation of TiO2 layers dissipate the stored energy within few nanoseconds by the recombination. Doping of the thin-film surface leads to enhancement of the excitons lifetime (as well as
in the Surface of Titanium Dioxide: Generation, Properties and Photocatalytic Application
Liang-Bin Xiong,Jia-Lin Li,Bo Yang,Ying Yu
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/831524
Abstract: Titanium dioxide (TiO2) is the most investigated crystalline oxide in the surface science of metal oxides. Its physical and chemical properties are dominantly determined by its surface condition. Ti3
Photocatalytic Activity of Titanium Dioxide Powder Fabricated from an Anodized Titanium Sheet under Ultra-Violet and Visible Light Irradiation  [PDF]
Michio Kaneko, Kiyonori Tokuno, Kazuo Yamagishi, Takao Wada, Tsuyoshi Hasegawa
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2017, DOI: 10.4236/jsemat.2017.71002
Abstract: A commercially pure titanium sheet with titanium carbide (TiC) precipitated in its surface layer was anodized in NH4NO3 aqueous solution and heat treated in air. The photocatalytic activity of titanium dioxide powder collected from the surface of the anodized titanium sheet was evaluated under ultra-violet and visible light irradiation. It showed relatively high photocatalytic activity in 0.1 mol/l potassium iodide solution, which was almost equal to the activity level of TiO2 powder (P-25) manufactured by Degussa Corporation. The better photocatalytic activity under ultra-violet irradiation is considered to be related to the formation of anatase type titanium dioxide. Photocatalytic activity under visible light irradiation was also observed, which was considered to be attributable to impurity doping, (carbon), in the titanium dioxide powder.
Photocatalytic degradation of dye effluent by titanium dioxide pillar pellets in aqueous solution
Li Yun-cang,Zou Lin-da,Hu Eric,
Li YC
,Zou LD,Hu E

环境科学学报(英文版) , 2004,
Abstract: Photocatalytic oxidation(PCO) process is an effective way to deal with organic pollutants in wastewater which could be difficult to be degraded by conventional biological treatment methods. Normally the TiO 2 powder in nanometre size range was directly used as photocatalyst for dye degradation in wastewater. However the titanium dioxide powder was arduous to be recovered from the solution after treatment. In this application, a new form of TiO 2(i. e. pillar pellets ranging from 2 5 to 5 3 mm long and with a diameter of 3 7 mm) was used and investigated for photocatalytic degradation of textile dye effluent. A test system was built with a flat plate reactor(FPR) and UV light source(blacklight and solar simulator as light source respectively) for investigating the effectiveness of the new form of TiO 2. It was found that the photocatalytic process under this configuration could efficiently remove colours from textile dyeing effluent. Comparing with the TiO 2 powder, the pellet was very easy to recovered from the treated solution and can be reused in multiple times without the significant change on the photocatalytic property. The results also showed that to achieve the same photocatalytic performance, the FPR area by pellets was about 91% smaller than required by TiO 2 powder. At least TiO 2 pellet could be used as an alternative form of photocatalyst in applications for textile effluent treatment process, also other wastewater treatment processes.
A Novel and Simple Route to Synthesis Nanocrystalline Titanium Carbide Via the Reaction of Titanium Dioxide and Different Carbon Source  [PDF]
Youjian Chen, Yongyong Deng, Hong Zhang, Lihua Wang, Jianhua Ma
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.211215
Abstract: A novel and simple route for synthesizing nanocrystalline ceramic powders in molten salt was introduced in the paper. Titanium carbide (TiC) was prepared via the reaction of metallic magnesium powders with titanium dioxide (TiO2), carbon source and molten salt in an autoclave at 650°C. Carbon source (oxalic acid and citric acid) in this paper was stable, low toxic and cheap. X-ray powder diffraction (XRD) patterns indicated that the products were cubic TiC. Scanning electron microscopy (SEM) images showed that the samples consisted of particles with an average size of 200 nm and 100 nm in diameter, respectively. Energy Dispersive Spectrometer (EDS) analysis of the samples suggested the products contained carbon and titanium elements. The product was also studied by the thermogravimetric analysis (TGA). It had good thermal stability and oxidation resistance below 350°C in air.
Optimization of Conditions for the Photocatalytic Degradation of EDTA in Aqueous Solution with Fe-Doped Titanium Dioxide  [PDF]
Tomoki Sugiyama, Ahmed H. A. Dabwan, Hideyuki Katsumata, Tohru Suzuki, Satoshi Kaneco
Open Journal of Inorganic Non-metallic Materials (OJINM) , 2014, DOI: 10.4236/ojinm.2014.43005
Abstract:
The conditions for photocatalytic degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solution with Fe-doped titanium dioxide (TiO2) were optimized. The degradation efficiencies with Fe-doped TiO2 were better, compared with those obtained with bare TiO2 and Pt-doped TiO2. The effect of various experimental factors, such as photocatalytic dosage, temperature, solution pH and light intensity on the photocatalytic degradation of EDTA by Fe-doped TiO2 was investigated. The photocatalytic degradation treatment for the wastewater containing EDTA is simple, easy handling and low cost.
New Preparation Method of Visible Light Responsive Titanium Dioxide Photocatalytic Films  [PDF]
Kaori Nishizawa, Masahisa Okada, Eiji Watanabe
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.53016
Abstract:

We report a new and simple preparation method of the visible light responsive Titanium dioxide (TiO2) photocatalytic films using sol-gel method and ultraviolet light (UV) irradiation. Proposed films were prepared on fused silica plates using titanium tetra-isopropoxide, urea, 2-methoxyethanol, water and UV irradiation. The 650°C-annealed films were carbon-containing anatase type TiO2, not carbon-doped ones. The prepared films absorbed visible light with wavelengths longer than 400 nm. Also, organic dyes were effectively photodegradated by visible light irradiation in the presence of these films.

Small Angle Neutron Scattering and X-Ray Diffraction Studies of Nanocrystalline Titanium Dioxide  [PDF]
M. Nasir Khan, J. Bashir
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.29115
Abstract: Nanocrystalline titanium dioxide powder is characterized for phase analysis as well as particle size and its distribution by x-ray diffraction and small angle neutron scattering measurements. Analysis of the SANS data in the momentum transfer range q = 0.1 - 1.8 nm–1 reveals an average particle size of 24.82 nm in good agreement with the particle size determined earlier by transmission electron microscopy. XRD measurement proves co-existence of rutile and anatase phases in this commercial TiO2 nanocrystalline powder.
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