Antibacterial Effect and Applications of Nano-TiO2
Posted: Nov 01, 2019
Compared with common materials, nanomaterials have a series of excellent properties that make nano-antibacterial agents prepared by nanotechnology have excellent antibacterial effects unmatched by traditional antibacterial agents. Nano antibacterial agents can be divided into two categories according to their mechanism of action on microorganisms: one is photocatalytic semiconductor materials such as nano zinc oxide, Nano-TiO2 (nano titanium dioxide), etc.; the other is antibacterial active metal nanomaterials.
As a new type of antibacterial material, nano-TiO2 (nano titanium dioxide) has the advantages of non-toxic, non-irritating, thermal stability, heat resistance, long-lasting antibacterial effect and high-efficiency sterilization. It is of great significance for preventing disease transmission, purifying environment, and protecting human health.
Advantages of nano-TiO2 as an antibacterial agent:
- It is non-toxic to human body and non-irritating to the skin
- Strong antibacterial ability and wide antibacterial range
- Odourless and Washable
- Long storage life
- Good thermal stability (no discoloration, no decomposition, no volatilization, no deterioration at high temperature)
- Nano-TiO2 antibacterial agents take only one hour to get effect, while other silver antibacterial agents take about 24 hours.
- Nano-TiO2 can permanently maintain antibacterial effect.
Applications of nano-TiO2 as an antibacterial agent
The nano-TiO2 powder can be blended with resin polymer material to prepare antibacterial plastic. The nano-TiO2 forms a surface layer having antibacterial ability on the surface of the resin, and then exerts a bactericidal action by contact with the packaged object. Since the nano-TiO2 is in the form of powder, it is generally required to uniformly disperse these powders into the resin during processing to obtain a desired antibacterial effect. Therefore, the antibacterial agent is usually first made into an antibacterial masterbatch, which is then mixed with the resin in a desired ratio. In addition, it is also necessary to consider the compatibility of the antibacterial agent with the resin, so the antibacterial agent is usually pretreated by adding a coupling agent or a dispersing agent.
Since titanium dioxide is photocatalytic and super-hydrophilic, the incorporation of nano-TiO2 into architectural coatings can improve the water repellency and anti-staining properties of the coating. The nano-TiO2 powder has a good shielding ability against ultraviolet rays, and thus can enhance the weather resistance of the coating. Compared with traditional coatings, the nano-TiO2-modified coatings have no harm to the human body and the environment. Nano TiO2 antibacterial coating has a long-lasting bactericidal effect, and it can also exert strong bactericidal effect under natural light, fluorescent lamp and even dark conditions.
Coating the titanium dioxide film on the finished ceramic product and then sintering it at a low temperature can achieve the effect of photocatalytic antibacterial action, thereby inhibiting the proliferation of bacteria on the ceramic surface. To achieve the effect of sterilization under low light, silver and copper ion compounds can be added to the titanium dioxide slurry. Antibacterial ceramic tiles and sanitary ceramics coated with nano-TiO2 film have been industrially produced in Japan, and are mainly used in hospitals, food processing industries etc., but the antibacterial effect is limited by the light conditions. In order to make full use of indoor sunlight and low light, new antibacterial ceramics have been actively developed.
Harmful air in the environment can be classified into indoor harmful gas and atmospheric pollutant. Indoor harmful gases mainly include formaldehyde released from decorative materials and methyl mercaptan, hydrogen sulfide and ammonia produced in the living environment. Nano-TiO2 photocatalyst can effectively decompose indoor and outdoor organic pollutants including formaldehyde, toluene, acetaldehyde and ammonia to purify air. The photocatalytic process of nano-TiO2 in air is to convert oxygen and water vapor into free radicals such as ·OH, ·O, ·HO under illumination, and then these free radicals combine with CO, SOx, NOx and other pollutants to form harmless products.
Sewage treatment should remove harmful substances, suspended solids, sediment, bacteria, viruses, odors, pigments and other pollutants from the water. Traditional water treatment methods have the disadvantages of high investment, high power consumption, low efficiency, high operating cost and secondary pollution. However, the development and application of nanotechnology has solved these problems. Through the photocatalysis of nanoparticles, nano-TiO2 can directly decompose organic or inorganic toxic pollutants under sunlight or ultraviolet light, and the pollutants can be completely mineralized or oxidized into harmless CO2 and H2O without causing secondary pollution. Nanotechnology has shown great potential for the degradation of nitrogen oxides and other organic matter in wastewater.
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