Photocatalytic titanium dioxide

Titanium dioxide photocatalytic oxidation of para-substituted phenols was studied by O Shea and Cardona (1994). The phenols were irradiated with UV light from mercury lamps emitting light at a wavelength of 350 nm. The phenols were studied in aqueous solution with an initial concentration of 0.1 M. TiOz was added to the solution at 0.1 g/L. The phenols were placed in the photoreactor for 30 min and then analyzed by gas chromatography to determine phenol concentrations. 

Ireland JC, Klosterman P, Rice EW, Clark RM. Inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation. Appl Environ Microbiol 1993 59 1668-1670. 

Pichat PG, MaiUard C, Amalric L, ITOliveira JC. Titanium dioxide photocatalytic destruction of water aromatic pollutants intermediates properties-degradabiUty correlation effects of inorganic ions and titanium dioxide surface area comparisons with hydrogen peroxide processes. Trace Metals Environ 1993 3 207-223. 

Numerous articles of a general interest have appeared on photocatalytic chemistry. These include nanoparticles, protection of buildings, antibacterial properties, ageing of pigment blends, modified titanium dioxides, photocatalytic paints, stabilization of pigmented systems, sensitization of acid dyes " and clay masterbatches. Anatase has been found to have a detri-... 

One of the most interesting processes based on titanium dioxide photocatalytic reactions in water systems is the mineralization reaction by which halogenated organic compounds can be converted into carbon dioxide, water, and halide ions. Removal of halogenated organic compounds is an important contribution to the solution of an environmental threat since most of these chemical substances exhibit rather high degrees of toxicity. 

Catalysis (qv) refers to a process by which a substance (the catalyst) accelerates an otherwise thermodynamically favored but kiaeticahy slow reaction and the catalyst is fully regenerated at the end of each catalytic cycle (1). When photons are also impHcated in the process, photocatalysis is defined without the implication of some special or specific mechanism as the acceleration of the prate of a photoreaction by the presence of a catalyst. The catalyst may accelerate the photoreaction by interaction with a substrate either in its ground state or in its excited state and/or with the primary photoproduct, depending on the mechanism of the photoreaction (2). Therefore, the nondescriptive term photocatalysis is a general label to indicate that light and some substance, the catalyst or the initiator, are necessary entities to influence a reaction (3,4). The process must be shown to be truly catalytic by some acceptable and attainable parameter. Reaction 1, in which the titanium dioxide serves as a catalyst, may be taken as both a photocatalytic oxidation and a photocatalytic dehydrogenation (5). 

A high purity titanium dioxide of poorly defined crystal form (ca 80% anatase, 20% mtile) is made commercially by flame hydrolysis of titanium tetrachloride. This product is used extensively for academic photocatalytic studies (70). The gas-phase oxidation of titanium tetrachloride, the basis of the chloride process for the production of titanium dioxide pigments, can be used for the production of high purity titanium dioxide, but, as with flame hydrolysis, the product is of poorly defined crystalline form unless special dopants are added to the principal reactants (71). 

Hydrothermal synthesis of titanium dioxides using acidic and basic peptizing agents and their photocatalytic activity on the decomposition of orange II... 

We have developed a compact photocatalytic reactor [1], which enables efficient decomposition of organic carbons in a gas or a liquid phase, incorporating a flexible and light-dispersive wire-net coated with titanium dioxide. Ethylene was selected as a model compound which would rot plants in sealed space when emitted. Effects of the titanium dioxide loading, the ethylene concentration, and the humidity were examined in batches. Kinetic analysis elucidated that the surface reaction of adsorbed ethylene could be regarded as a controlling step under the experimental conditions studied, assuming the competitive adsorption of ethylene and water molecules on the same active site. 

The photocatalytic activity of 20mesh wire-net photocatalyst was observed to be nearly equal to that of 350mesh one under the same amount of titanium dioxide loading (1.88 g). 

Tacconi NR, Chenthamarakshan CR, Rajeshwar K, Tacconi El (2005) Selenium-modified titanium dioxide photochemical diode/electrolyte junctions Photocatalytic and electrochemical preparation, characterization, and model simulations. 1 Phys Chem B 109 11953-11960... 

Phillips, L.G. and Barbano, D.M., The influence of fat substitutes based on protein and titanium dioxide on the properties of low fat milks, J. Dairy Sci., 80, 2726, 1997. Choi, J.Y. et ah, Photocatalytic antibacterial effect of TiOj film formed on Ti and TiAg. J. Biomed. Mater. Res. B Appl. Biomater., epub., 2006. 

Titanium dioxide is one of the most intensely studied oxides in view of both its use as a support and its special photocatalytic properties. Of special recent... 

Chen J, Ollis DF, Rulkens WM (1999) Kinetic processes of photocatalytic mineralization of alcohols on metallized titanium dioxide. Water Res 33 1173-1180... 

Zhou et al. obtained nitrogen-doped titanium dioxide replicas via a two-step infiltration process with natural leaves as templates [220]. The replicas inherited the hierarchical structures of the natural leaf at the macro-, micro-, and nanoscales. These materials showed enhanced light-harvesting and photocatalytic hydrogen evolution activities. The photocatalytic water splitting activity of the artificial leaf structures was eight times higher than that of titanium dioxide synthesized without templates. 

Minero, C., Mariella, G., Maurino, V., and Pelizzetti, E. (2000) Photocatalytic transformation of organic compounds in the presence of inorganic anions. 1. Hydroxyl-mediated and direct electron-transfer reactions of phenol on a titanium dioxide-fluoride system. Langmuir,... 

Demeestere, K., Dewulf, J., Ohno, T., Salgado, P.H., and Van Langenhove, H. (2005) Visible light mediated photocatalytic degradation of gaseous trichloroethylene and dimethyl sulfideonmodified titanium dioxide. Applied Catalysis B Environmental,... 

Hirano, K., Inoue, K., and Yatsu, T. (1992) Photocatalysed reduction of C02 in aqueous Ti02 suspension mixed with copper powder. Journal of Photochemistry and Photobiology A Chemistry, 64 (2), 255-258. Adachi, K., Ohta, K., and Mizuno, T. (1994) Photocatalytic reduction of carbon dioxide to hydrocarbon using copper-loaded titanium dioxide. Solar Energy,... 

Shiraishi, Y., Saito, N., and Hirai, T. (2005) Adsorption-driven photocatalytic activity of mesoporous titanium dioxide. Journal of the American Chemical Society, 127 (37), 12820-12822. 

Shiraishi, Y., Sugano, Y., Inoue, D., and Hirai, T. (2009) Effect of substrate polarity on photocatalytic activity of titanium dioxide particles embedded in mesoporous silica. Journal of Catalysis, 264 (2), 175-182. 

Li, X. and Kutal, C. (2002) Photocatalytic selective epoxidation of styrene by molecular oxygen over highly dispersed titanium dioxide species on silica. Journal of Materials Science Letters, 21 (19), 1525-1527. 

Brezova, V., Blazkova, A., Surina, I., and Havlmova, B. (1997) Solvent effect on the photocatalytic reduction of 4-nitrophenol in titanium dioxide suspensions. Journal of Photochemistry and Photobiology A Chemistry, 107 (1-3), 233-237. 

Ferry, J.L. and Glaze, W.H. (1998) Photocatalytic reduction of nitro organics over illuminated titanium dioxide role ofthe Ti02 surface. Langmuir, 14 (13), 3551-3555. 

Liu, Z He, Y Li, F. and Liu, Y. (2006) Photocatalytic treatment of RDX wastewater with nano-sized titanium dioxide. Environmental Science and Pollution Research, 13, 328—332. 

Kato, S., Hirano, Y., Iwata, M., Sano, T., Takeuchi, K. and Matsuzawa, S. (2005) Photocatalytic degradation of gaseous sulfur compounds by silver-deposited titanium dioxide. Applied Catalysis B Environmental, 57, 109-115. 

---