first: Deep ultraviolet waveband is the most effective in disinfection and sterilization

Ultraviolet disinfection is an old and effective method. Basking in the sun is the most primitive use of ultraviolet rays to kill mites, disinfect and kill bacteria.

Li Jinmin, director of the State Key Laboratory of semiconductor lighting joint innovation, said that the principle of ultraviolet disinfection and sterilization is to use high-energy ultraviolet light to break the DNA double helix chain, to achieve the inactivation of bacteria and viruses. It is necessary to meet certain requirements to realize effective sterilization and disinfection by ultraviolet rays. We should pay attention to the wavelength, irradiation dose and time of ultraviolet light source, that is, it must be UVC band with a wavelength less than 280nm. For different bacteria and viruses, it must meet certain irradiation dose and time, otherwise, it cannot be inactivated.

According to Yan Jianchang, a researcher at the Institute of Semiconductors of the Chinese Academy of Sciences, the UV band can be divided into UVA, UVB, and UVC according to wavelength-division. UVC is the band with the shortest wavelength and the highest energy. In fact, for sterilization and disinfection, the most effective band is UVC, which is called a deep-ultraviolet band. Compared with chemical sterilization, UV has the advantage of high sterilization efficiency, which is usually completed in a few seconds and does not produce other chemical pollutants.

UV can also inactivate microorganisms. The household can purify the water by installing the ultraviolet water purification system, and the air purifier equipped with an ultraviolet lamp can treat the floating bacteria in the air innocuously. UV disinfection is also used in sewage treatment plants, food factories, breweries and beverage factories.

UV sterilization lamp should be purchased on demand

UV sterilization lamp can be divided into three types according to its shape: double end lamp, single end lamp, and self ballasting lamp. It can be divided into two types according to whether it contains ozone or not.

Wang Di, an engineer at the health home appliances testing center of China Household Appliances Research Institute, said that ozone lamps should not be used in crowded areas and indoors. Consumers should pay attention to the relationship between UV intensity and space size when purchasing a UV germicidal lamp. Usually, a 1.5W ultraviolet germicidal lamp is needed for every cubic meter of space. Users can choose products with corresponding power according to the actual situation of their home.

The ultraviolet germicidal lamp is usually used in places where bacteria are easy to grow, such as kitchens, bathrooms and other dark damp places. It can also be used in spaces with high environmental quality requirements, such as wards, operating rooms, and other medical places. Now, a UV sterilization lamp is also widely used in some electrical products, such as air purifiers, fresh air blowers, clothing care machine and other indoor purification devices and clothing care disinfection devices.

It should be reminded that the UV lamp has a certain life, and the lamp should be replaced in time. According to the requirements of GB / T 19258-2012 standard, the service life of the ultraviolet lamps is not less than 5000h, the average service life is 8000h, and the high-performance products can reach more than 10000 hours. Wang Di suggested that consumers replace the lamp every 1-2 years and wipe the outer surface of the lamp with alcohol every two weeks to ensure the ultraviolet radiation intensity.

Skills in using the ultraviolet germicidal lamp

Due to the damage of ultraviolet to biological cells, when using ultraviolet germicidal lamps, we should pay attention not to directly irradiate human skin, let alone directly look at the lamp tube with our eyes.

Under the premise of ensuring safety, how to use ultraviolet sterilization lamp scientifically and effectively? Wang Di said that we should pay attention to the location, create the best use environment, and pay attention to the length of use.

First, due to the weak penetration ability of ultraviolet in the air, it is difficult to achieve the long-distance sterilization ability, so it should be placed in the main sterilization position as far as possible when using, such as the middle of the room, or the place where bacteria are easy to grow, 1.5m-2m away from the surrounding area is appropriate.

Second, pay attention to the impact of the use environment on the sterilization effect. In general, the output intensity of ultraviolet is the highest and the sterilization effect is the best when the temperature is between 27 ℃ and 40 ℃. Besides, the use environment should be clean and dry. A large amount of moisture and dust in the environment will interfere and weaken the ultraviolet, and reduce the actual ultraviolet intensity. When used at home, try to close the doors and windows, draw the curtains, turn off the lights, and ensure that the room is in a dark condition, which is more conducive to the sterilization of ultraviolet rays. For places where bacteria and other microorganisms are easy to breed, such as bed covers, the bed can be expanded, the contact area can be increased, which is more conducive to the sterilization and disinfection of ultraviolet rays.

Third, the ultraviolet sterilization lamp should be used to ensure sufficient UV exposure time. Research shows that after 5 minutes of irradiation, it is an effective sterilization time when it reaches 30 minutes, it can achieve daily disinfection effect, when the irradiation time reaches 60 minutes, it can kill most of the bacteria and other microorganisms in the air.

Yan Jianchang said that at present, most of the deep UV light sources used in the field of civil and industrial disinfection and sterilization are mercury lamps. In the future, the deep UV LED-based on gallium nitride wide bandgap semiconductor material is expected to replace the traditional mercury lamp, and its application scope is more easily expanded to portable disinfection electronic products, such as mother and baby sterilizer, elevator armrest sterilizer, mini washing machine built-in UV sterilizer, sweeping robot, etc.

In short, in daily life, “less going out, no dinner, frequent hand washing and more ventilation” is still the lowest cost and the most effective means of epidemic prevention. In the face of the epidemic situation, when using an ultraviolet sterilization lamp for sterilization and disinfection, we must be scientific and reasonable and attach great importance to the safety of use.