Type of radiation sterilization device
Writer: Sterilization Time: 2020-09-02 Browse: 804 ℃
At present, there are two kinds of irradiation devices: one is gamma ray irradiation device, the other is electron accelerator irradiation device (divided into X-ray irradiation device and electron line irradiation device, mainly electronic line irradiation device).
Radiation can be divided into two categories: particle radiation and electromagnetic radiation.
Particle radiation is some high-speed moving particles, which have both energy and static mass. They transmit energy to other substances by consuming their own kinetic energy; electromagnetic radiation is essentially electromagnetic wave, with only energy but no static mass.
According to the different modes of action, radiation is usually divided into two types: ionizing radiation and non ionizing radiation. High speed charged particles, such as particles A and β, can directly ionize matter and belong to direct ionized particles; non charged particles such as ionizing photons (X-ray and y-ray) and neutrons are indirectly ionized particles, which are generated by the charged secondary particles when they interact with matter. Radiation caused by any ray consisting of directly or indirectly ionized particles, or a mixture of the two, is collectively referred to as ionizing radiation.
X-ray is a kind of ionizable electromagnetic radiation
X-ray is a kind of ionizable electromagnetic radiation. As an energy carrier, its photons have no mass and no charge. Before losing energy completely, they can penetrate quite thick materials, and can ionize matter by producing charged secondary particles when interacting with substances. The y-ray comes from the nuclear transition. The daughter nuclei formed in the process of radioactive decay are in excited and unstable states. When the subnuclei transition from high excited state to low excited state or ground state, gamma rays are released. For example, the CO and 3CS elements of radioisotopes can produce y-rays during their decay. Gamma rays destroy microorganisms by cutting off chemical bonds in important biological molecules, such as DNA, and by producing free radicals and active molecules that chemically corrode organisms.
The interaction between radiation and matter
Although there are many ways of interaction between gamma ray and substance, only three kinds of disinfection energy need to be considered, namely Compton effect, photoelectric effect and electron pair generation effect.
(1) Compton effect: when the incident photons are collided by the loose electrons in an atom, the scattered photons and electrons escape in different directions. At this time, the photon energy decreases, and almost all the energy lost by photons is transferred to the electrons as energy. For many medical devices, the main interaction between polymer and cellulose is Compton effect.
(2) Photoelectric effect: the energy of y-ray photons is less than 0me, and the emitted photons interact with the layer orbit electrons of atoms, and the photons are absorbed, and the energy of photons is transferred to the inner layer electrons escaping from the atoms.
(3) Electron pair formation: when the energy of the incident photon is large, the photon will be transformed into positive and negative electrons under the influence of atomic nucleus. The common result of three kinds of effects on ray and matter is to produce secondary and continue to use with matter, causing ionization and excitation of matter.
Killing effect of ionizing radiation on microorganisms
The direct and indirect effects of radiation sterilization are the direct and indirect effects of radiation on the destruction of cells through the direct energy transfer with biological macromolecules in microbial cells; the effect of radiation on the destruction of intracellular macromolecules caused by radiolysis of water in microbial cells is called indirect action. Radiation damage to microbial cells is mainly caused by direct and indirect effects.
Characteristics of irradiation technology
The radiation emitted by the radioactive source has a strong penetrating ability. It can go deep into the material for "processing", which is carried out at room temperature. Because the processors are high energy rays and highly active intermediates caused by them, rather than molecular thermal motion, they have low energy consumption, no residues and no environmental problems. So it's clean processing technology. Moreover, the reaction is easy to control, the process is simple, suitable for industrialization and large-scale production. Its advantages are summarized as follows:
1. The process is simple and easy to control.
2. Energy saving and high processing efficiency: the energy consumption of irradiation processing is only 1 / 40-1 / 200 of that of thermal processing and chemical processing, and 1 / 20 of that of freezing method.
3. No environmental pollution; no chemical drug residues; no damage to the appearance quality and internal characteristics of processed products.
4. No impurity will be brought into the process; it can be processed with packaging to improve the efficiency without secondary pollution.
5. It can be said that radiation processing technology is a kind of high and new technology. Compared with other processing technologies, this new technology has obvious characteristics
(1) The technology involved in a wide range of knowledge intensive, has a strong professional nature.
(2) It can be combined with all walks of life in the national economy. It has strong permeability and can give full play to the role of radiation processing.
(3) The output value increases, the added value is high, and the social benefit is good.
(4) The industrial market is extensive and concentrated, with great potential and good development prospects.
(5) One time investment is big. In the construction of irradiation equipment, safety protection, monitoring system, the investment is often large.