1., sterilization function
Long-term sterilization under the action of ultraviolet rays in light. The experiment shows that anatase nano-TiO _ 2 with the concentration of 0. 1mg/cm3 can completely kill malignant Hela cells, and with the increase of SOD addition, the efficiency of photocatalytic killing cancer cells by TiO _ 2 is also improved. The killing rate of Bacillus subtilis is different. Aspergillus Niger spores, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Salmonella, Cladosporium and Aspergillus all reached more than 98%. Advanced treatment of tap water by TiO2 _ 2 photocatalytic oxidation can greatly reduce the number of bacteria in water, and it has no mutagenic effect after drinking, reaching the standard of safe drinking water. Adding nano-TiO2 _ 2 into the paint can make antibacterial and antifouling paint with sterilization, antifouling, deodorization and self-cleaning, which can be used in hospital wards, operating rooms, home bathrooms and other places where bacteria are dense and easy to breed, and play the roles of purifying the air, preventing infection and deodorizing. Can effectively kill harmful bacteria and so on.
2, anti-ultraviolet function
Nano-titanium dioxide can not only absorb ultraviolet rays, but also reflect and scatter ultraviolet rays and transmit visible light. It is a kind of physical ultraviolet shielding agent with excellent performance and great development prospect.
Anti-ultraviolet mechanism of nanometer titanium dioxide;
According to different wavelengths, ultraviolet light is divided into short-wave region 190 ~ 280 nm, medium-wave region 280~320 nm and long-wave region 320 ~ 400 nm. The ultraviolet energy in the short-wave region is the highest, but it is blocked when it passes through the ozone layer. Therefore, it is generally the ultraviolet rays in the medium wave region and the long wave region that cause harm to the human body.
Nano-titanium dioxide has strong ultraviolet resistance because of its high refraction and high light activity. Its anti-ultraviolet ability and its mechanism are related to its particle size: when the particle size is large, the blocking of ultraviolet rays is mainly reflection and scattering, and it is effective for both medium-wave and long-wave ultraviolet rays. The sun protection mechanism is simple covering, which belongs to general physical sun protection and has weak sun protection ability; With the decrease of particle size, light can penetrate through the surface of nano-TiO _ 2 particles, and the reflection and scattering of ultraviolet rays in long wave region are not obvious, but the absorption of ultraviolet rays in medium wave region is obviously enhanced. Its sun protection mechanism is to absorb ultraviolet rays, mainly absorbing ultraviolet rays in the medium wave region.
It can be seen that the sunscreen mechanism of nano-TiO _ 2 for ultraviolet rays with different wavelengths is different. The main barrier of long-wave ultraviolet is scattering, and the main barrier of medium-wave ultraviolet is absorption.
Nano-titanium dioxide shows excellent absorption performance in different wavelength regions. Compared with other organic sunscreens, nano-titanium dioxide has the characteristics of non-toxicity, stable performance and good effect. Japan Shiseido uses 10- 100nm nano-titanium dioxide as a sunscreen ingredient to add to lipsticks and creams, and its sunscreen coefficient can be as high as SPF1-19.
Because of its small particle size and high activity, nano-TiO _ 2 can not only reflect and scatter ultraviolet rays, but also absorb ultraviolet rays, so it has strong blocking ability to ultraviolet rays. VK-T02 nano-titanium dioxide has a higher absorption peak in the ultraviolet region than some organic ultraviolet protectants with the same dosage. What is more valuable is that it is also a broad-spectrum shielding agent, unlike organic ultraviolet protectants which only absorb UVA or UVB. It can also transmit visible light. When it is added to cosmetics, the whiteness of skin is natural. Unlike pigment-grade TiO2, it can't transmit visible light, resulting in unnatural color on the user's face.
With its transparency and ultraviolet absorption capacity, nano-TiO2 _ 2 can also be used as food packaging film, ink, coating, textile products and plastic filler, which can replace organic ultraviolet absorber and improve the aging resistance of coatings.
3. Photocatalytic function
It is found that when titanium dioxide is activated under the action of sunlight or ultraviolet rays in light, it can produce free radicals with high catalytic activity, strong photooxidation and reduction ability, and catalyze the photolysis of various organic substances such as formaldehyde and some inorganic substances attached to the surface of objects. Can play a role in purifying indoor air.
4, anti-fog and self-cleaning function
TiO2 _ 2 film has super hydrophilicity and super durability under illumination, so it has anti-fog function. If a titanium oxide film is coated on the rearview mirror of an automobile, even if the moisture or water vapor in the air condenses, the condensed water will not form a single water drop, but a water film will be evenly spread on the surface, so there will be no fog of light scattering on the surface. When the rain rushes through, the rain attached to the surface will quickly spread into a uniform water film, and will not form water droplets that distract the line of sight, so that the surface of the rearview mirror will keep its original brightness and improve driving safety.
Nano-titanium dioxide has a strong "super-hydrophilicity", and it is not easy to form water droplets on its surface. Under the irradiation of visible light, nano-titanium dioxide can act on hydrocarbons. Using this effect, a thin layer of nano-TiO2 _ 2 can be coated on the surface of glass, ceramics and ceramic tiles. Through the photocatalytic reaction of titanium dioxide, the organic pollutants adsorbed on the surface of titanium dioxide can be decomposed into CO2 and O2, which are washed away with the rest inorganic substances by rain, thus realizing the self-cleaning function. The laboratory in Tokyo, Japan has successfully developed a self-cleaning ceramic tile. The surface of this new product has a thin layer of nano titanium dioxide. Under the irradiation of light, any substance adhering to the surface, including oil stains and bacteria, can further oxidize these hydrocarbon substances into gases or substances that are easy to erase due to the catalytic effect of nano-titanium dioxide. The photocatalysis of nano-TiO2 _ 2 makes it easy to clean the glass of high-rise buildings, the tiles that are easy to stick in the kitchen, the rearview mirror and the front window of cars.
5. Nano-titanium dioxide can be used as raw materials for lithium batteries and solar cells.
Nano-titanium dioxide (TA 18) was added to the lithium battery;
Nano-titanium dioxide has excellent high rate performance, cycle stability, fast charge-discharge performance and high capacity, as well as good reversibility of lithium intercalation, which has a good application prospect in the field of lithium batteries.
1) nano-titanium dioxide can effectively reduce the capacity attenuation of lithium batteries, increase the stability of lithium batteries and improve the electrochemical performance.
2) Improve the first discharge specific capacity of battery materials.
3) The polarization of LiCoO2 during charge and discharge is reduced, and the material has higher discharge voltage and more stable discharge effect.
4) A proper amount of nano titanium dioxide can exist in a loose state, which reduces the stress between particles and the tiny strain of structure and volume caused by the cycle process, and increases the stability of the battery.
In chemical energy solar cells, nano-titanium dioxide crystals have the characteristics of high photoelectric conversion rate, low cost, simple process and stable performance. Its photoelectric efficiency is stable above 10%, its manufacturing cost is only1/5 ~1/and its service life can reach more than 20 years.
3. In Ni-Cd battery, nano-TiO _ 2 has the characteristics of good conductivity and wide working temperature range.
6. Nano-titanium dioxide can replace PVA in textiles.
In the process of spinning fiber into yarn, sizing is necessary to reduce warp breakage. PVA is a polymer compound, which is difficult to degrade in natural environment. It has been used in China since 1950s and 1960s. Therefore, it has been classified as "unclean pulp" in some European countries and has been banned. The EU's restrictions on PVA will also be the focus of China's green trade barriers for cotton textile exports. The domestic textile industry has been seeking to develop green and environmentally friendly slurry to replace refractory PVA, which is the goal of "breaking the wall".
Nanometer titanium dioxide T25F is used for textile sizing. Through the perfect combination with starch, the comprehensive weaving performance of yarn is improved, the dosage of PVA is reduced, the sizing time is short, the sizing cost is reduced, the sizing benefit is improved, and many problems such as difficulty in desizing PVA sizing and environmental pollution are solved. Nano-titanium dioxide mainly replaces PVA in yarn, and plays the role of fitting hairiness, filling gaps and lubrication.
7. Application of nanometer titanium dioxide in high-grade automobile paint
Adding the mixed pigment of nanometer titanium dioxide (T20Q) and aluminum powder or mica pearlescent pigment coated with nanometer titanium dioxide into the paint can produce mysterious and changeable color change with the angle, mainly because when the incident light hits the nanometer titanium dioxide particles, the blue light will be strongly scattered, and as a result, the green light and red light (yellow phase) after the blue light is removed are reflected by the aluminum sheet into positive reflection light, that is, the scattered light is strong blue phase light, and the reflected light is strong yellow phase light. Titanium dioxide T20Q microcrystals with a particle size of tens of nanometers also endow the coating with metallic luster effect, pearlescent effect, flashing effect and color enhancement effect, which makes the automobile surface we see as if it is a pearl flake shining, giving people a sense of depth and layering.
This is the mystery of color-changing cars. As a high-tech technology, nanotechnology is changing our lives!
8. Other functions
Nano-titanium dioxide also has a good degradation effect on some plastics, freon and surfactant SDBS.
It is also found that TiO2 can also absorb harmful gases. For example, coating olefin polymer fibers containing TiO2 on ceramics containing calcium phosphate can absorb different acid-base gases for a long time.
In view of the above functions, nano-titanium dioxide has a very broad prospect. Its research and utilization will bring great changes to people's lives.
Application 1, Cosmetics
Any titanium dioxide has certain ultraviolet absorption function, and excellent chemical stability, thermal stability, non-toxic and other properties. Ultrafine titanium dioxide has smaller particle size (transparency) and greater activity, so it has stronger ability to absorb ultraviolet rays. In addition, titanium dioxide is the most widely used inorganic raw material in cosmetics, such as decoloring power, hiding power, clear color tone, low grindability and good dispersibility. In 1980s, the annual consumption of titanium dioxide in the world cosmetics industry was estimated to be 3500t-4000t, and now it is estimated to be above 5000t and below 10000t. Different qualities of titanium dioxide can be selected according to their different functions in cosmetics.
Using the whiteness and opacity of titanium dioxide, the color range of cosmetics can be very wide. When titanium dioxide is used as a white additive, anatase titanium dioxide is mainly used, but considering the hiding power and light resistance, rutile titanium dioxide is the best.
Titanium dioxide for cosmetics requires high purity and strict content of harmful impurities. For example, the European Food Additives Law (applicable to cosmetics) stipulates that the acid-soluble substance titanium dioxide is used in cosmetics.
According to the food, drug and cosmetic regulations of the US Food and Drug Administration (FDA), the total amount of titanium dioxide used as cosmetic, SiO4 _ 4 _ 4 and/or Al _ 2O _ 3 used as dispersion aid and Pb should not exceed 2%.
Nano-titanium dioxide is transparent, so it has many excellent characteristics and functions that ordinary cosmetic raw materials do not have in terms of blocking ultraviolet rays, transmitting visible light and safety.
Nano-titanium dioxide can not only scatter ultraviolet rays (wavelength 200 nm-400 nm), but also absorb ultraviolet rays, so it has a strong ability to shield ultraviolet rays and can be used as an excellent sunscreen to make sunscreen cosmetics.
Because nanometer titanium dioxide is transparent, it can be used to make transparent skin cream. This skin cream is very popular in Japan and other countries because of its delicate paste and natural skin feeling. Japan needs 1000 tons of nano-titanium dioxide as a sunscreen for cosmetics every year.
2, antibacterial agent
At present, nano-titanium dioxide has become one of the hot spots in development and research because of its excellent antibacterial properties. Nano-titanium dioxide is widely used in antibacterial water treatment equipment, food packaging, sanitary daily necessities (antibacterial floor tiles, antibacterial ceramic sanitary facilities, etc.). ), cosmetics, textiles, antibacterial tableware and chopping boards, antibacterial carpets, new house decoration and new furniture for removing harmful gases, and durable consumer goods such as refrigerators, medical dressings and medical devices made of antibacterial mortar, antibacterial coatings, antibacterial stainless steel plates and aluminum plates for building.
Antimicrobial agents are mostly organic substances and are widely used in food, detergent, textiles and cosmetics. But they also have some disadvantages, such as poor heat resistance, high volatility, easy decomposition to produce harmful substances and poor safety. Therefore, some inorganic antibacterial agents have been actively developed, and ultrafine TiO2 is one of them. Because antibacterial agents need to reach a certain amount in the product, the following principles must be followed when selecting antibacterial agents:
(1) is safe and nontoxic to human body and has no irritation to skin;
⑵ Strong antibacterial ability and wide antibacterial range;
(3) No peculiar smell, strange smell, light appearance color and small smell;
(4) Good thermal stability, no discoloration, decomposition, volatilization, deterioration, etc. At high temperature;
5] cheap price, easy source, etc.
Ultrafine TiO2 _ 2 is an inorganic component, which is non-toxic, odorless, non-irritating, good in thermal stability and heat resistance, non-combustible and white in itself, completely in line with the above principles.
prospect
Nano-titanium dioxide is a transparent substance, which has the functions of shielding ultraviolet rays and producing color effects. Because of the high unity of transparency and anti-ultraviolet function, it has been widely used in many aspects such as sun protection and skin care, plastic film products, wood protection, transparent and durable topcoat, fine ceramics and so on. Especially in the late 1980s, this kind of effect pigment, which can produce attractive effects of "different angles and different colors", was successfully applied to the topcoat of luxury cars, attracting worldwide attention. Developed countries such as the United States, Japan and Europe are very active in this research work, and have invested a lot of manpower and material resources and made long-term plans. So far, they have made many amazing achievements in the fierce international market competition and formed a high-tech nano-material industry. The production of fine inorganic materials with high added value and high function has achieved good economic and social benefits, and nano-oxide materials are becoming a hot spot in China industry.
With the deepening of the research on nano-materials, people pay more and more attention to nano-assembly system and nano-structured material system synthesized by artificial assembly, which means that the research on nano-materials can design, assemble and create new systems according to people's wishes, and make the systems have expected characteristics and technological leaps more purposefully, which further opens the market door for the application of nano-materials and forms a large number of high-tech products in a wide range of fields. Such as magnetic memory, optical memory, liquid crystal display and optical functional film in information and communication; Electronic components development, solar energy supply, thermal insulation materials, sensors for measurement and control technology; Anti-aging rubber in structural ceramics and functional ceramics, functional coatings, photocatalytic degradation agents, clean antibacterial materials, ultra-high magnetic energy balance water-soil magnets, etc. In the market growth of nano-materials, products manufactured by O-3D structure technology, ultra-precision machining technology, ultra-thin film production technology and transverse structure technology have the most market growth potential.
Relevant research also shows that the market application and development of nano-materials will be accelerated in the next 10 year, because the patents in the field of nano-materials in industrial countries have been increasing at an annual rate of more than 20% since 1993. According to the data, the investment of scientific research funds in nano-materials and related fields in western industrial countries reaches about 7.5 billion US dollars every year. International competition in this field is becoming increasingly fierce.