Views:28 Author:Allon Publish Time: 2020-04-08 Origin:Site
The development of biological science makes humans realize the existence of microorganisms. There are many microorganisms that can make people sick and even cause death in severe cases. The purpose of disinfection is to take some means to kill these pathogenic microorganisms. These pathogenic microorganisms include bacteria, fungi and viruses.
Disinfection can destroy the living environment of bacteria and viruses through various or physical or chemical means, and then destroy their biological structure, thereby killing them.
Temperature is one of the important conditions that affect the survival of living things. High temperature can cause the protein to solidify, change its structural properties, and inactivate it. Whether it is bacteria or viruses, protein inactivation will threaten its survival. Different bacterial viruses have different heat resistance.
There are many types of high-temperature disinfection. Water bath heating, high pressure steam, flame burning, high temperature baking, etc. These methods all kill bacteria (including bacterial spores) and viruses by changing the temperature of the bacteria's living environment. One of the more common is pasteurization and high temperature baking.
Pasteurization is a method of disinfecting food invented by the French microbiologist Pasteur. The lethal temperature of bacteria is 68 ° C. Keep heating in the container to 60-80 ° C for 30 minutes, and then quickly cool to 4 ° C. Pasteurization can kill most pathogenic and non-pathogenic bacteria, but a small number of more heat-resistant bacteria or their spores remain.
Pasteurization is used in certain food processing industries, such as milk, beer, jam, canned food, etc.
Pasteurization features: shorter sterilization time, incomplete sterilization, lower sterilization cost, suitable for food preservation.
Dry heat sterilization is a method of sterilizing items. Dry heat sterilization refers to baking items in a high-temperature drying oven. Suitable for solid objects, especially inorganic materials such as glassware, test tubes, etc. It can also be used to bake organic materials such as banknotes and cloth. But when baking organic items, the temperature should not be too high, otherwise it will be burnt or even burned. Dry heat sterilization is generally heated at 70 ° C for 30 minutes.
When COVID-19 is sterilized by dry heat method, it can be killed by heating above 56 ° C for 30 minutes.
Dry heat disinfection features: high disinfection temperature, short disinfection time, relatively complete disinfection, suitable for disinfecting the surface of heatable items
UV refers to ultraviolet rays, which are divided into UVA, UVB, UVC, etc. according to different wavelengths. The ultraviolet light used for disinfection and sterilization is UVC with a wavelength of 100-280 nm. UVC can directly penetrate bacterial cell membranes and damage bacterial genetic material such as RNA and DNA. UV does not directly kill bacterial viruses, its main role is to destroy the genetic material of bacterial viruses, making bacterial viruses unable to reproduce.
The disinfection effect of UV is related to the irradiation intensity, irradiation distance, and irradiation time. UV can be used to disinfect the surface of air, water and objects. For article disinfection, the irradiation time of more than 24min is enough to complete the disinfection. When the ambient temperature is lower than 20 ° C or higher than 40 ° C and the relative humidity is higher than 60%, it is necessary to extend the disinfection time in a timely manner. For space disinfection, comprehensive consideration is required, and the irradiation time is arranged according to the power of the UV lamp and the size of the space, and it is generally better to keep it above 60 minutes.
UV disinfection features: broad-spectrum disinfection, stable performance, low operating cost, disinfection capacity declines with distance, poor penetration, and shadows affect disinfection when there are many room items.
Alcohol disinfection is the use of 75% volume fraction of medical alcohol for wipe disinfection, which can be used for disinfection of human skin, surface of articles, and environmental surfaces. Experiments have shown that alcohol with 75% -78% concentration has the best disinfection effect and can effectively kill many bacteria. Alcohol at this concentration will gradually penetrate into the bacteria, dehydrating, denaturing and solidifying its protein, and eventually killing the bacteria.
Alcohol disinfection can also kill some viruses. Especially viruses with an envelope structure similar to bacterial cell membranes such as influenza viruses. COVID-19 also has an envelope structure and has been proven to have a killing effect on alcohol disinfection.
Alcohol disinfection features: low price, strong sterilization ability, effective for some viruses, volatile, and certain safety risks when used.
Ozone is a naturally occurring strong oxidant. Ozone disinfection is the use of an ozone machine to artificially create ozone and then discharge the ozone into the air or water for disinfection. It is generally believed that when ozone comes into contact with bacteria, it will first react with proteins on its cell membrane, causing the permeability of the bacterial cell membrane to change. Ozone can enter bacteria, destroy proteins and genetic material, and kill bacteria. The mechanism of action of ozone on viruses is similar.
When using ozone for space disinfection, it can be treated for 30-40 minutes. Ozone spreads fast, ignoring the types of pathogenic viruses. Ozone is suitable for air disinfection, article surface disinfection, and water disinfection. It will not produce harmful substances after disinfection, environmental protection without secondary pollution.
Ozone disinfection features: broad-spectrum disinfection, large power consumption, strong diffusibility, and strong disinfection ability.