Titanium Dioxide Nanomaterials

Metal ions or their oxides were combined with Ti02 nanomaterials in order to improve the catalytic activity and selectivity of the Ti02 photocatalysts. Ag-doped Ti02 was used to degrade gaseous sulfur compounds [158], Ag nanoparticle-doped Ti02 

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Furthermore, perlite has been reported to be a suitable support for titanium dioxide nanomaterials [516-520]. Basically an amorphous alumina silicate (see Table 13), Perlite is an industrial mineral and a commercial product, useful for its light weight after processing. Due to its low density and relatively low price, many commercial applications for perlite have been developed including construction and manufacturing fields, horticultural aggregates, filter aid and fillers [519]. 

X. Chen, S.S. Mao, Titanium dioxide nanomaterials S3mthesis, properties, modifications and applications . Chemical Reviews, 107, 2891-2959, (2007). 

Chapter 5 - Supported and Immobilized Titanium Dioxide Nanomaterials... 

Chen, X. and Mao, S.S. 2007. Titanium dioxide nanomaterials Synthesis, properties, modifications, and applications. Chem. Rev. 107 2891-2959. 

Seery MK, George R, Floris P, Pillai SC. Silver doped titanium dioxide nanomaterials for enhanced visible light photolysis. J Photochem Photobiol A 2007 189 258-63. 

Chen and S. S. Mao, Titanium Dioxide Nanomaterials Synthesis, Properties, Modifications, and Applications, Chem. Rev., 107,2891-2859 (2007). 

N anomaterials have been around for hundreds of years and are typically defined as particles of size ranging from 1 to 100 nm in at least one dimension. The inorganic nanomaterial catalysts discussed here are manganese oxides and titanium dioxide. Outside the scope of this chapter are polymers, pillared clays, coordination compounds, and inorganic-organic hybrid materials such as metal-organic frameworks. 

Nanomaterials can also be tuned for specific purposes through doping. Specifically, the effect of the presence of manganese oxides on photocatalysis involving primarily titanium dioxide will be considered in this section. Titanium dioxide is a well-known photocatalyst and will be considered separately. K-OMS-2, which has a cryptomelane structure, is illustrated in Figure 8.4. Not all the literature discussed in this section, however, involves OMS tunnel structure materials. For example, amorphous manganese oxide (AMO) is also discussed as a photocatalyst. Manganite (MnOOH) is also included in battery applications. 

Cataluminescence by nano-materials of titanium dioxide and strontium carbonate have also been reported [21-23]. The CTL emission on these nanomaterials is in the diffusion-controlled condition at low temperatures. This means that these materials have high CTL catalytic activity. Systematic research on CTL catalysts should be expected in the future. 

Keywords metal nanoparticles, nanomaterials, photoelectrochemistry, photocatalysis, electrocatalysis, semiconductor, titanium dioxide. 

On the other hand, liquid phase deposition (LPD) has been demonstrated as a flexible wet chemical method for preparing metal oxide nanostructured films on electrode surfaces. By the LPD process, electroactive titanium dioxide (Ti02) films were prepared on graphite, glassy carbon and ITO. The electrochemical properties of such LPD Ti02 films were dependent upon the film thickness controlled by the deposition time. The LPD technique was easily combined with other techniques, e.g., seed-mediated growth, which could provide metal/metal oxide composite nanomaterials. Moreover, hybrid nanostructured films were facilely obtained by doping dyes, surfactants and other... 

As nanomaterials are transported through the environment or the human body, they may undergo transformations that could influence their properties. Oxidation-reduction (redox) reactions are known to cause environmentally and biologically relevant transformations for certain nanomaterials. Titanium dioxide (TiOa), for example, can oxidize orgaiuc compounds in the environment and inactivate microorganisms (26,27). This oxidative property of Ti02 has led to applications such as skin care and water treatment, where antimicrobial properties are desirable, but it may be detrimental to microorganisms that are beneficial to the natural environment. Solar... 

The metal and metal oxide nanomaterials usually applied as antimicrobial agents are silver (Ag), gold, zinc oxide, silica, titanium dioxide, alumina and iron oxides. The antimicrobial features of nanozinc oxide and magnesium oxide have recently been revealed. Compared with nanosilver, zinc oxide and titanium dioxide NP are expected to lead to less expensive and safer food packaging solutions in the future... 

Concurrent with the increasing development and uses of nanomaterials, there is an equal effort in studying their potential toxicity. Titanium dioxide, for example, is widely used in food products and cosmetics and considered safe, but studies of nano titanium dioxide particles which are small enough to enter the body in several ways may be toxic according to some studies. The expanded use of nanofillers in consumer products has generated safety concerns that have resulted in proposals for detailed studies by the Food and Drug Administration. ... 

The toxicity of nanomaterials is not well understood, and many commentators have expressed concern that the unique properties of nanomaterials maybe associated with unknown risks. Some of the concern is because of the ability of small particles to penetrate Hving tissue. There are conflicting study conclusions on whether inhaled nanoparticles may mimic the action of asbestos in the lungs. Some studies conclude that they do cause inflammation because they can reach the lung structures that exchange oxygen and carbon dioxide from the blood. However, other studies conclude that the results are equivocal. Similarly, titanium dioxide nanoparticles have been the subject of several studies to determine whether or not they can penetrate human skin when they are used in sunscreen formulations. While studies have shown that they do not penetrate beyond the outer layer of skin, the studies have been criticized because they were aU on intact, unabraded healthy adult skin, and so the risks in actual use may not be the same as indicated by those studies. In addition, many formulations contain moisturizers that are designed to penetrate skin, and the effects of these moisturizers on the skin penetration of titanium dioxide nanoparticles are unknown. ... 

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