Nano is derived from the Greek word for "dwarf ". 1 nanometer is approximately 100,000 times thinner than a human hair.
Nanotechnology is a rapidly growing science of producing and utilizing nano-sized particles that measure in nanometers (1 nm = 1 billionth of a metre). The term nanoparticle is generally used to indicate particles with dimensions less than 100 nanometers (one nanometer is one billionth of a meter).
For comparison, a human hair is about 100,000 nm in diameter, while a smoke particle is about 1,000 nm in diameter.
Anti-mould & anti-moss
Titanium is the 9th-most common element on earth and titanium oxide is used as a white pigment in paint and cosmetics. As a pigment a lower grade titanium dioxide is used.
For photocatalyst applications like air-purifying, anti-bacterial use and self-cleaning purposed a very high-grade photo reactive titanium dioxide is used. Its high levels of reaction to light enable it to act as a catalyst to produce large quantities of hydroxyl radicals that cause the oxidation of organic matter, sterilise most bacteria and clear the air of pollutants.
Titanium dioxide can do this without changing its own structure, thereby causing it to have an indefinite life span. Add to this the fact that it is non-toxic to the environment and humans, it is no wonder it is being talked about in the same glowing terms used to describe the future of plastic when it first came to the market.
Safety of TiO2
TiO2 used as photocatalyst is physically and chemically safe, the US certified it as a food additive in 1968 and Japan did in 1983.
It is now used widely in making white chocolates and functional cosmetics, including lipsticks.
The Food Analysis Center of Japan Food Research Laboratories and Mitsubishi Chemical Safety Institute Ltd. demonstrated its safety through skin simulating tests and acute oral toxicity test.
Photo-Catalysis is defined as "acceleration by the presence of a catalyst". A catalyst does not change in itself or being consumed in the chemical reaction. This definition includes photosensitization, a process by which a photochemical alteration occurs in one molecular entity as a result of initial absorption of radiation by another molecular entity called the photosensitized.
Chlorophyll of plants is a type of photocatalyst called photosynthesis. Photocatalysis is when chlorophyll captures sunlight to turn water and carbon dioxide into oxygen and glucose.
Photocatalysis is the creation of a strong oxidation agent to breakdown any organic matter to carbon dioxide and water in the presence of the photocatalyst, light and water.
VOCs - Volatile Organic Compounds are gases given off by a number of indoor sources. Formaldehyde is one of the most common VOCs. Formaldehyde is a colourless gas with an unpleasant smell. It is common in many building materials such as plywood, particleboard, and glues.
Formaldehyde is also found in furnishings (furniture, drapes and carpets) and in some types of foam insulation. Other sources of VOCs and formaldehyde include burning of fuels: gas, wood, kerosene, and tobacco products.
VOCs also come from personal care products such as perfumes and hair spray, from cleaning agents and dry cleaning fluid, paints, lacquers and varnishes, and from copying and printing machines.
VOCs can be released from a product for several years, though the amounts given off tend to be less as the product ages and "dries out".
VOCs can cause irritation of the eyes, nose and throat, nausea and dizziness, and skin problems.
Higher amounts can cause irritation of the lungs and wheezing.
Higher exposures to formaldehyde may also cause memory problems and anxiety.
The process of combining oxygen with some other substance or a chemical change in which and atom loses electrons. The most powerful advanced oxidation systems are based on the generation of hydroxyl radicals.
They act as very powerful disinfecting agents by oxidizing cells of micro-organizms, causing rupture of the cell and leakage of vital composition.
Micro-organisms carry a negative charge while TiO2 coated surface carries a positive charge. This creates an "electromagnetic" attraction between the microbe and treated surface. Once contact is made, the microbe is oxidized and dies instantly.
Although it is originally water-soluble, it dries quickly after application and becomes water-insoluble. It also becomes very hard in ten to fourteen days after application. It does not come off unless the surface is polished.
Titanium dioxide is merely the catalyst and is not changed, its effect is semi-permanent except when walls and ceilings are repainted.
Dust particle is no longer attracted to the oily components on the TiO2 treated surface.
Hydrophilic ~ water loving. When the surface of photocatalytic film is exposed to light, the contact angle of the phtocatalyst surface with water is reduced gradually. After enough exposure to light, the surface reaches a super-hydrophilic state. In other words, it does not repel water at all, so water cannot exist in the shape of a drop, but spreads flatly on the surface of the substrate.
The water takes the form of a highly uniform thin film, which behaves optically like a clear sheet of glass.
The hydrophilic nature of titanium dioxide, coupled with the gravity, will enable the dust particles to be swept away following the water stream, thus making the product self-cleaning.