Books are the treasure house of human knowledge, people's requirements for spiritual civilization are getting higher and higher, and the number of family books is increasing. Because books stored for a long time tend to be moldy and moth-eaten in humid environment, books read by many people tend to be infected with a large number of microorganisms, even including pathogenic microorganisms such as hepatitis B virus and tuberculosis, so disinfection is needed. There are three common disinfection treatments: ozone, chemical disinfectants and ultraviolet rays.

Ozone is a strong oxidant, and the sterilization process belongs to biochemical oxidation reaction. Principle of ozone disinfection: the enzyme needed to decompose glucose in bacteria is oxidized, which inactivates and kills bacteria; Directly interact with bacteria and viruses, destroy their organelles, DNA and RNA, destroy the metabolism of bacteria, and lead to bacterial death; Invasion of cells through cell membrane tissue acts on lipoproteins in the outer membrane and lipopolysaccharide inside, causing permeability distortion and dissolution death of bacteria. Ozone sterilization is a method of bacteria lysis, which has the advantages of thorough sterilization, no residue and broad spectrum, and can kill bacterial propagules, spores, viruses, fungi and so on. And destroy the botulinum toxin. In addition, O3 can kill mold. Because of its poor stability, O3 will soon decompose into oxygen or a single oxygen atom, and the single oxygen atom will combine itself into oxygen molecules without any toxic residue.

But the harm caused by ozone can not be ignored. Ozone is toxic to people, and the allowable concentration in the atmosphere is 0.2mg/m3 as stipulated by the state, so disinfection must be carried out without people. Ozone is a strong oxidant, which can damage many kinds of articles. The higher the concentration, the more serious the damage to the goods. It can cause green rust spots on copper sheets, aging, discoloration and decreased elasticity of rubber, leading to brittle cracking, bleaching and fading of fabrics. When using, it should be noted that ozone has a stimulating effect on human respiratory mucosa. When the ozone concentration in the air reaches 1mg/L, it can be smelled out. When it reaches 2.5-5mg/L, it can cause accelerated pulse, fatigue and headache. If people stay for more than 65,438+0 hours, emphysema may occur, leading to death. Therefore, disinfection is carried out in the absence of people, and it won't matter if you stop entering for 30-50 minutes after disinfection. Ozone decomposes itself into oxygen within 30-60 minutes after disinfection, and it still has sterilization effect within the decomposition time, so if the room is sealed after disinfection, it can still be kept for 30-60 minutes. ?

Chemical disinfectants can be divided into seven categories. Oxidative disinfectant: the sterilization mechanism is to release new ecological atomic oxygen and oxidize the active groups in bacteria; Sterilization is characterized by rapid and intense action, which can kill all microorganisms, including bacterial spores and viruses. Mainly surface disinfection, such as chlorine dioxide, hydrogen peroxide, ozone, etc. Such a disinfectant is a disinfectant. Aldehyde disinfectants: the sterilization mechanism is to denature or alkylate protein; The characteristic of sterilization is that it is effective for bacteria, spores, fungi and viruses. But the temperature has a great influence. Such as formaldehyde, glutaraldehyde, etc. This disinfectant can be used as a disinfectant. Phenolic disinfectant: the sterilization mechanism is to denature, precipitate or inactivate the enzyme system; The characteristic of sterilization is that it is effective for fungi and some viruses. Alcohol disinfectant: the sterilization mechanism is to denature protein and interfere with metabolism; Sterilization is effective for bacteria, but not for spores, fungi and viruses, such as ethanol and ethyl propanol. This disinfectant belongs to intermediate disinfectant and can only be used for general disinfection. Alkaline and salt disinfectants: the sterilization mechanism is to denature, precipitate or dissolve protein; The characteristic of sterilization is that it can kill bacterial propagules, but it can't kill bacterial spores, viruses and some microorganisms that are difficult to kill. Weak bactericidal effect and strong corrosiveness, such as nitric acid, caustic soda and salt. Can only be used as a general preventive disinfectant. Halogen disinfectant: The sterilization mechanism is to oxidize the active genes in bacteria and combine with amino groups to denature protein. It is characterized by killing most microorganisms, mainly surface disinfection, unstable nature, and the sterilization effect is greatly affected by environmental conditions. Surfactant disinfectants: the sterilization mechanism is to change the permeability of cell membrane, make cytoplasm leak, hinder breathing or denature protease. The characteristic of sterilization is that it can kill bacterial propagules, but it has poor effect on spores, fungi, viruses and tuberculosis. The effect is good under alkaline and neutral conditions. Chemical disinfectants generally have shortcomings such as incomplete sterilization, dead angle, heavy workload, residual pollution or pungent smell, which are harmful to human health.

Ultraviolet rays can destroy the molecular structure of DNA (deoxyribonucleic acid) or RNA (ribonucleic acid) in bacterial viruses, leading to the death of growing cells and/or regenerative cells, thus achieving the effect of sterilization and disinfection. When the wavelength is in the range of 240~280nm (especially when the wavelength is 253.7nm), the bactericidal effect is the strongest. Ultraviolet disinfection is an efficient, safe, environmentally friendly and economical technology. At present, it is widely used in hospitals, schools, nurseries, cinemas, buses, offices, families and so on. It can purify the air, eliminate the musty smell and produce a certain amount of negative oxygen ions. The air in the room disinfected by ultraviolet rays is particularly fresh. In public places, ultraviolet disinfection can prevent some germs from spreading through the air or the surface of objects. Because ultraviolet rays can kill cells, we should be careful not to directly irradiate people's skin to avoid injury.

At present, the book sterilizer uses this principle to sterilize books.

The value required for ultraviolet rays to kill various viruses.

According to related papers, when the energy value of ultraviolet irradiation is above 308J/㎡, it can effectively kill bacteria and viruses, including novel coronavirus.

References:

Valladislaw J. kowalski, Thomas J. Walsh, Vidmantas Peter Lettice. (2020.3).2020 Coronavirus Pneumonia-19 Coronavirus Ultraviolet Sensitivity. The gate of research

Reference link:

/publication/339887436 _ 2020 _ coronavirus pneumonia-19 _ coronavirus _ ultraviolet _ susceptibility