Titanium dioxide
You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.
| Titanium dioxide | |
|---|---|
| Image:Titanium(IV) oxide.jpg | |
| Image:Rutile-unit-cell-3D-balls.png | |
| IUPAC name | Titanium dioxide Titanium(IV) oxide |
| Other names | Titania Rutile Anatase Brookite |
| Identifiers | |
| CAS number | |
| RTECS number | XR2775000 |
| Properties | |
| Molecular formula | TiO2 |
| Molar mass | 79.87 g/mol |
| Appearance | White solid |
| Density | 4.23 g/cm3 |
| Melting point |
1870 °C (3398 °F) |
| Boiling point |
2972 °C (5381.6 °F) |
| Solubility in other solvents | Insoluble |
| Thermochemistry | |
| Std enthalpy of formation ΔfH | −944 kJ/mol |
| Hazards | |
| EU classification | not listed |
| NFPA 704 |
|
| Flash point | non-flammable |
| Related Compounds | |
| Other cations | Titanium(II) oxide Titanium(III) oxide Titanium(III,IV) oxide Zirconium dioxide Hafnium dioxide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references | |
|
WikiDoc Resources for Titanium dioxide | |
|
Articles | |
|---|---|
|
Most recent articles on Titanium dioxide Most cited articles on Titanium dioxide | |
|
Media | |
|
Powerpoint slides on Titanium dioxide | |
|
Evidence Based Medicine | |
|
Clinical Trials | |
|
Ongoing Trials on Titanium dioxide at Clinical Trials.gov Trial results on Titanium dioxide Clinical Trials on Titanium dioxide at Google
| |
|
Guidelines / Policies / Govt | |
|
US National Guidelines Clearinghouse on Titanium dioxide NICE Guidance on Titanium dioxide
| |
|
Books | |
|
News | |
|
Commentary | |
|
Definitions | |
|
Patient Resources / Community | |
|
Patient resources on Titanium dioxide Discussion groups on Titanium dioxide Patient Handouts on Titanium dioxide Directions to Hospitals Treating Titanium dioxide Risk calculators and risk factors for Titanium dioxide
| |
|
Healthcare Provider Resources | |
|
Causes & Risk Factors for Titanium dioxide | |
|
Continuing Medical Education (CME) | |
|
International | |
|
| |
|
Businness | |
|
Experimental / Informatics | |
Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [1] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.
Titanium dioxide, also known as titanium(IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2. When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. It is noteworthy for its wide range of applications, from paint to sunscreen to food colouring.
Natural occurrence
Titanium dioxide occurs in four forms:
- rutile, a tetragonal mineral usually of prismatic habit, often twinned;
- anatase or octahedrite, a tetragonal mineral of dipyramidal habit;
- brookite, an orthorhombic mineral. Both anatase and brookite are relatively rare minerals;
- Titanium dioxide (B) or TiO2(B), a monoclinic mineral.
Titanium dioxide occurrences in nature are never pure; it is found with contaminant metals such as iron. The oxides can be mined and serve as a source for commercial titanium. The metal can also be mined from other minerals such as ilmenite or leucoxene ores, or one of the purest forms, rutile beach sand.
Production
Crude titanium dioxide is purified via titanium tetrachloride in the Chloride process. In this process, the crude ore (containing at least 90% TiO2) is reduced with carbon, oxidized with chlorine to give titanium tetrachloride. This titanium tetrachloride is distilled, and re-oxidized with oxygen to give pure titanium dioxide.[1]
Applications
Titanium dioxide is the most widely used white pigment because of its brightness and very high refractive index (n=2.4), in which it is surpassed only by a few other materials. When deposited as a thin film, its refractive index and colour make it an excellent reflective optical coating for dielectric mirrors and some gemstones, for example "mystic fire topaz". TiO2 is also an effective opacifier in powder form, where it is employed as a pigment to provide whiteness and opacity to products such as paints, coatings, plastics, papers, inks, foods, medicines (i.e. pills and tablets) as well as most toothpastes. Used as a white food colouring, it has E number E171. In cosmetic and skin care products, titanium dioxide is used both as a pigment and a thickener. It is also used as a tattoo pigment and styptic pencils.
This pigment is used extensively in plastics and other applications for its UV resistant properties where it acts as a UV reflector.
In ceramic glazes titanium dioxide acts as an opacifier and seeds crystal formation. In almost every sunscreen with a physical blocker, titanium dioxide is found both because of its refractive index and its resistance to discolouration under ultraviolet light. This advantage enhances its stability and ability to protect the skin from ultraviolet light. Sunscreens designed for infants or people with sensitive skin are often based on titanium dioxide and/or zinc oxide, as these mineral UV blockers are less likely to cause skin irritation than chemical UV absorber ingredients, such as avobenzone.
Titanium oxide is also used as a semi-conductor.[1]
As a photocatalyst
Titanium dioxide, particularly in the anatase form, is a photocatalyst under ultraviolet light. Recently it has been found that titanium dioxide, when spiked with nitrogen ions, is also a photocatalyst under visible light. The strong oxidative potential of the positive holes oxidizes water to create hydroxyl radicals. It can also oxidize oxygen or organic materials directly. Titanium dioxide is thus added to paints, cements, windows, tiles, or other products for sterilizing, deodorizing and anti-fouling properties and is also used as a hydrolysis catalyst. It is also used in the Graetzel cell, a type of chemical solar cell.
Titanium dioxide has potential for use in energy production: as a photocatalyst, it can:
- carry out hydrolysis, i.e., break water into hydrogen and oxygen. Were the hydrogen collected, it could be used as a fuel. The efficiency of this process can be greatly improved by doping the oxide with carbon, as described in "Carbon-doped titanium dioxide is an effective photocatalyst" [2].
- produce electricity when in nanoparticle form. Research suggests that by using these nanoparticles to form the pixels of a screen, they generate electricity when transparent and under the influence of light. If subjected to electricity on the other hand, the nanoparticles blacken, forming the basic characteristics of a LCD screen. According to creator Zoran Radivojevic, Nokia has already built a functional 200 by 200 pixels monochromatic screen which is energetically self-sufficient.
As TiO2 is exposed to UV light, it becomes increasingly hydrophilic; thus, it can be used for anti-fogging coatings or self-cleaning windows. TiO2 incorporated into outdoor building materials, such as paving stones in noxer blocks, can substantially reduce concentrations of airborne pollutants such as volatile organic compounds and nitrogen oxides.
For wastewater remediation
TiO2 offers great potential as an industrial technology for detoxification or remediation of wastewater due to several factors.
- The process occurs under ambient conditions.
- The formation of photocyclized intermediate products, unlike direct photolysis techniques, is avoided.
- Oxidation of the substrates to CO2 is complete.
- The photocatalyst is inexpensive and has a high turnover.
- TiO2 can be supported on suitable reactor substrates.
Other applications
It is also used in resistance-type lambda probes (a type of oxygen sensor).
Titanium dioxide is what allows osseointegration between an artificial medical implant and bone.
Titanium dioxide in solution or suspension can be used to cleave protein that contains the amino acid proline at the site where proline is present. This breakthrough in cost-effective protein splitting took place at ASU in 2006.[1]
Titanium dioxide on silica is being developed as a form of odor control in cat litter. The purchased photocatalyst is vastly cheaper than the purchased silica beads, per usage, and prolongs their effective odor-eliminating life substantially.
The Pilkington Activ glass has a special nano-scale, extremely thin hydrophobic coating of microcrystalline titanium oxide which catalyses the break-down of organic surface contamination by ultraviolet light from the sun. [3]
Historical uses
The Vinland map, the map of America ("Vinland") that was supposedly drawn during mid-15th century based on data from the Viking Age, has been declared a forgery on the basis that the ink on it contains traces of the TiO2-form anatase; TiO2 was not synthetically produced before the 1920s. Recently (1992) a counter-claim has been made that the compound can be formed from ancient ink.
Titanium dioxide white paint was used to paint the Saturn V rocket, which is so far the only rocket that has sent astronauts to the moon. In 2002, a spectral analysis of J002E3, a celestial object, showed that it had titanium dioxide on it, giving evidence it may be a Saturn V S-IVB.
See also
- Noxer, a building material incorporating TiO2.
References
External links
- International Chemical Safety Card 0338
- NIOSH Pocket Guide to Chemical Hazards
- "Fresh doubt over America map", bbc.co.uk, 30 July, 2002
- A description of TiO2 photocatalysis
- "Smog-busting paint soaks up noxious gases", Jenny Hogan, 'newscientist.com, 04 February 2004
- Crystal structures of the three forms of TiO2
- Kutal, C., Serpone, N. (1993). Photosensitive Metal Organic Systems: Mechanistic Principles and Applications. American Chemical Society, Washington D.C
- "Architecture in Italy goes green", Elisabetta Povoledo, International Herald Tribune, November 22, 2006
- "A Concrete Step Toward Cleaner Air", Bruno Giussani, BusinessWeek.com, November 8, 2006
de:Titandioxidfr:Dioxyde de titane it:Diossido di titanio hu:Titán-dioxid nl:Titaanwit ja:二酸化チタンfi:Titaanidioksidi sv:Titandioxid
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
