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Sterilization Function
It can sterilize for a long time under the action of ultraviolet rays in light. Experiments have proved that anatase nano-TiO₂ at a concentration of 0.1mg/cm³ can completely kill malignant HeLa cells. Moreover, with the increase in the amount of superoxide dismutase (SOD) added, the efficiency of TiO₂ in photocatalytically killing cancer cells also increases. The killing rates of Bacillus subtilis var. niger spores, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Salmonella, Lactobacillus and Aspergillus are all above 98%. When tap water is deeply treated by TiO₂ photocatalytic oxidation, the number of bacteria in the water can be greatly reduced. There is no mutagenic effect after drinking, meeting the standards of safe drinking water. Adding nano-TiO₂ to coatings can produce antibacterial and antifouling coatings with functions of sterilization, antifouling, deodorization and self-cleaning. They can be applied in places where bacteria are dense and easy to multiply, such as hospital wards, operating rooms and family bathrooms, to purify the air, prevent infections, and remove odors. It can effectively kill harmful bacteria and so on.
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Anti-ultraviolet Function
Nano-TiO₂ can absorb ultraviolet rays, as well as reflect and scatter them, and it can also transmit visible light. It is a physically shielding ultraviolet protective agent with superior performance and great development prospects.
The anti-ultraviolet mechanism of nano-titanium dioxide: According to different wavelengths, ultraviolet rays are divided into the short-wave region of 190 - 280 nm, the medium-wave region of 280 - 320 nm, and the long-wave region of 320 - 400 nm. The ultraviolet energy in the short-wave region is the highest, but it is blocked when passing through the ozone layer. Therefore, the ultraviolet rays that usually harm the human body are in the medium-wave and long-wave regions. The strong anti-ultraviolet ability of nano-titanium dioxide is due to its high refractive index and high photoactivity. Its anti-ultraviolet ability and mechanism are related to its particle size: When the particle size is relatively large, the blocking of ultraviolet rays is mainly achieved through reflection and scattering, and it is effective for both ultraviolet rays in the medium-wave and long-wave regions. The sunscreen mechanism is simple coverage, which belongs to general physical sunscreen and has relatively weak sunscreen ability. As the particle size decreases, light can pass through the particles of nano-TiO₂. The reflection and scattering of ultraviolet rays in the long-wave region are not obvious, while the absorption of ultraviolet rays in the medium-wave region is significantly enhanced. Its sunscreen mechanism is to absorb ultraviolet rays, mainly absorbing ultraviolet rays in the medium-wave region. It can be seen that the sunscreen mechanisms of nano-titanium dioxide for ultraviolet rays of different wavelengths are different. The blocking of ultraviolet rays in the long-wave region is mainly achieved through scattering, and the blocking of ultraviolet rays in the medium-wave region is mainly achieved through absorption. Nano-titanium dioxide exhibits excellent absorption performance in different wavelength regions. Compared with other organic sunscreen agents, nano-titanium dioxide has the characteristics of being non-toxic, having stable performance and good effects. Shiseido in Japan uses nano-titanium dioxide with a particle size of 10 - 100 nm as a sunscreen ingredient added to lipsticks and creams, and its sun protection factor can reach SPF 11 - 19. Due to its small particle size and high activity, nano-titanium dioxide can not only reflect and scatter ultraviolet rays but also absorb them, thus having a stronger blocking ability against ultraviolet rays. Compared with some organic ultraviolet protective agents at the same dose, VK-T02 nano-titanium dioxide has a higher absorption peak in the ultraviolet region. More importantly, it is a broad-spectrum shielding agent. Unlike organic ultraviolet protective agents, it does not only absorb UVA or UVB alone. It can also transmit visible light. When added to cosmetics, the skin looks naturally white. Unlike pigment-grade TiO₂, which cannot transmit visible light and causes an unnatural pale color on the user's face. Utilizing the transparency and ultraviolet absorption ability of nano-TiO₂, it can also be used as food packaging films, inks, coatings, textile products and plastic fillers. It can replace organic ultraviolet absorbers and can be used in coatings to improve the anti-aging ability of coatings.
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Photocatalytic Function
Research results have found that under the action of ultraviolet rays in sunlight or lamplight, TiO₂ can be activated to generate free radicals with high catalytic activity, which can produce strong photo-oxidation and reduction abilities and can catalyze and photolyze various organic substances such as formaldehyde and some inorganic substances attached to the surface of objects. It can play a role in purifying indoor air.
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Anti-fogging and Self-cleaning Functions
The TiO₂ film has superhydrophilicity and super-permanence under light irradiation, so it has an anti-fogging function. For example, if a layer of titanium oxide film is coated on the rearview mirror of a car, even if the moisture or water vapor in the air condenses, the condensed water will not form individual water droplets but will form a water film that spreads evenly on the surface, so fog caused by light scattering will not occur on the surface. When rain washes over it, the rainwater attached to the surface will also quickly spread to form a uniform water film, so that water droplets that would block the line of sight will not form, keeping the surface of the rearview mirror shiny as before and improving driving safety. Nano-TiO₂ has a strong "superhydrophilicity", and water droplets are not easily formed on its surface. Moreover, nano-TiO₂ can act on hydrocarbons under visible light irradiation. Utilizing this effect, a thin layer of nano-TiO₂ can be coated on the surfaces of glass, ceramics and ceramic tiles. By using the photocatalytic reaction of titanium oxide, the organic pollutants adsorbed on the surface of titanium oxide can be decomposed into CO₂ and O₂, and together with the remaining inorganic substances, they can be washed away by rainwater, thus realizing the self-cleaning function. In Tokyo, Japan, someone has successfully developed self-cleaning ceramic tiles in the laboratory. There is a thin layer of nano-TiO₂ on the surface of this new product. Any substances stuck on the surface, including oil stains and bacteria, can be further oxidized into gases or substances that are easily wiped off under the irradiation of light due to the catalytic action of nano-TiO₂. The photocatalytic action of nano-TiO₂ makes it easy to clean the glass of high-rise buildings, ceramic tiles that are easily soiled in the kitchen, rearview mirrors and front windshields of cars.
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Nano-titanium dioxide can be used as a raw material for lithium batteries and solar cells.
When nano-titanium dioxide (TA18) is added to lithium batteries:
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Nano-titanium dioxide has excellent high-rate performance and cycle stability, fast charge-discharge performance, relatively high capacity, and good reversibility of lithium insertion and extraction. It has good application prospects in the field of lithium batteries.
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It can effectively reduce the capacity attenuation of lithium batteries, increase the stability of lithium batteries, and improve electrochemical performance.
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It can increase the first discharge specific capacity of battery materials.
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It reduces the polarization of LiCoO₂ during the charge-discharge process, enabling the material to have a higher discharge voltage and a more stable discharge effect.
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An appropriate amount of nano-titanium dioxide can exist in a loose state, reducing the stress between particles and the small structural and volumetric strains caused during the cycle process, and increasing the stability of the battery.
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In chemical energy solar cells, nano-titanium dioxide crystals have the characteristics of high photoelectric conversion rate, being able to greatly improve the energy conversion rate of solar cells, being low in cost, having a simple process and stable performance. Its photoelectric efficiency is stably above 10%, and the production cost is only 1/5 to 1/10 of that of silicon solar cells, and its lifespan can reach more than 20 years.
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In nickel-cadmium batteries, nano-titanium dioxide has the characteristics of good electrical conductivity and a wide working temperature range.
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The application of nano-titanium dioxide in textiles can replace PVA.
During the process of spinning fibers into yarns, sizing is necessary to reduce the breakage of warp yarns. PVA, a polymer compound that has been used in China since the 1950s and 1960s, is very difficult to degrade in the natural environment. Therefore, it has been listed as an "unclean sizing agent" in some European countries and has been prohibited from use by explicit regulations. The EU's restrictions on PVA will also be the focus of attention regarding the green trade barriers for China's cotton textile exports. Developing green and environmentally friendly sizing agents to replace the difficult-to-degrade PVA has always been the "breakthrough" goal sought by the domestic textile industry. The nano-titanium dioxide T25F used in textile sizing agents, through perfect combination with starch, can improve the comprehensive weaving performance of yarns, reduce the amount of PVA used, shorten the cooking time of sizing agents, reduce the cost of sizing agents, improve the sizing efficiency of yarns, and also solve many problems such as the difficulty in desizing PVA sizing agents and environmental pollution. In yarns, nano-titanium dioxide mainly replaces PVA and plays roles in smoothing fiber flyings, filling gaps and lubricating.
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The application of nano-titanium dioxide in high-grade automotive paints.
When nano-sized titanium dioxide (T20Q) is mixed with aluminum powder mixed pigments or mica pearlescent pigments coated with nano-titanium dioxide and added to coatings, the coating can produce a mysterious and changeable effect of color change with different viewing angles. This is mainly because when incident light shines on nano-titanium dioxide particles, due to their small particle size, blue light will be strongly scattered. As a result, green light and red light (showing a yellow hue) after the removal of blue light are reflected by aluminum flakes to become specular reflection light, that is, the scattered light is light with a strong blue hue, and the reflected light is light with a strong yellow hue (golden color). Different hues can be seen with different viewing angles. The microcrystals of titanium dioxide T20Q with a particle size of dozens of nanometers also endow the coating film with metallic luster effect, pearlescent effect, flashing effect and color enhancement effect, making the surface of the car look as if pearl flakes are shining, giving a sense of depth and layering. This is the secret of color-changing cars. Nanotechnology, as a high-tech, is changing our lives!
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Other functions.
Nano-titanium dioxide also has a very good degradation effect on some plastics, Freon and the surfactant SDBS. It has also been found that TiO₂ has an absorption function for harmful gases. For example, olefin polymer fibers containing TiO₂ coated on calcium phosphate-containing ceramics can continuously absorb different acidic and alkaline gases for a long time.
In view of the above functions, nano-titanium dioxide has a very broad prospect. Research and utilization of it will bring huge changes to people's lives.
