UV light application and sterilization principle
UV dose plays a vital role in the sterilization process. Under the condition of sufficient ultraviolet dose, the inactivated virus and bacteria will not resurrect, but when the dose is insufficient, many viruses and bacteria that are inactivated by ultraviolet radiation can repair their damaged structures through the assisting effect of light. UV radiometer is used to test the uv intensity of the light sources.
Ultraviolet light application and sterilization principle
According to the wavelength, ultraviolet (Ultra Violet, UV) light is usually divided into UVA (315nm-400nm), UVB (280nm-315nm), UVC (200nm-280nm). Among them, the wavelength UVC band is also called the "solar blind" band. Due to the strong absorption of ozone in the atmosphere, there is almost no ultraviolet light in this band in the near-Earth solar spectrum. The main applications of UVC mainly include water/air/surface disinfection/purification, analytical instruments (spectrophotometry, liquid chromatography, gas chromatography, etc.), and mineral analysis. The UVC band has short wavelength and high energy. It destroys the molecular structure of microorganisms (bacteria, viruses and other pathogens) in a short time. By destroying the DNA and RNA of microorganisms to prevent their reproduction, it can achieve high-efficiency and rapid broad-spectrum bactericidal effects, thereby preventing water , The air and the surface of the object are sterilized, so that the cells cannot be regenerated, so it is widely used in the sterilization and disinfection of water and air. The data shows that with only 30mW/cm2 of UVC ultraviolet radiation intensity, almost 100% of most bacteria can be killed in one second, the effect is very significant, and it can be widely used in the medical and health fields. In the field of personal health and household hygiene, ultraviolet light can be used for disinfection of water cups and chopsticks, air purification and sterilization, killing worms, sterilization and deodorization of footwear and socks, and sterilization of baby bottles.
UV germicidal effect
Depending on the type of microorganism, the UV sterilization time and dosage are also different. Different bacterial species have different absorption peaks of ultraviolet light. For example, the maximum absorption wavelengths of DNA and E. coli are both 265nm, while the maximum absorption wavelengths of Cryptosporidium and bacteriophages are 261nm and 271nm, respectively. Therefore, the required sterilization time should also be different. When the ultraviolet radiation intensity is 3×104μW/cm2, the time required to kill viruses and bacteria, mold spores, and algae bacteria are 0.1～1.0s, 1.0～8.0s, and 5.0～40.0s respectively. According to the research team of Dong Xiaoping, an expert from the Institute of Viral Disease Control and Prevention of the Chinese Center for Disease Control and Prevention, discovered that the SARS virus can be killed by UVC irradiation with an intensity greater than 90 μW/cm2 in 30 minutes. UV dose plays a vital role in the sterilization process. Ultraviolet dose can be expressed as the product of ultraviolet intensity and exposure time. Under the condition of sufficient ultraviolet dose, the inactivated virus and bacteria will not resurrect, but when the dose is insufficient, many viruses and bacteria that are inactivated by ultraviolet radiation can repair their damaged structures through the assisting effect of light. When the UV dose is the same, high-intensity, short-time or low-intensity, long-term irradiation can be used to achieve the purpose of sterilization. To kill 1×104 Helicobacter/mL, the UV dose is about 30 mJ/cm2, and to kill the same number of spores, the UV dose is about 70 mJ/cm2.
