The benefits of air purifiers: eliminate smoke and dust, sterilize and disinfect, eliminate odors, remove formaldehyde, etc., and purify various harmful substances in the room. Of course, because there are many brands of air purifiers, the functions vary depending on the brand you choose, but in general they are similar.
1. Adsorptive filtration: Activated carbon layer Activated carbon is a porous carbon-containing substance. It has a highly developed pore structure. The porous structure of activated carbon provides it with a large surface area and can interact with gas ( Impurities) are fully contacted, thus giving activated carbon its unique adsorption properties, making it very easy to absorb and collect impurities. Just like magnetism, all molecules have an attraction to each other.
Adsorbs many free harmful gases.
Note: Ordinary activated carbon cannot adsorb all toxic gases, has low efficiency and is prone to saturation and desorption.
2. Mechanical filtration: HEPA (High efficiency particulate air Filter), which means high-efficiency air filter in Chinese, is a filter that meets HEPA standards. The effective efficiency reaches 99.998% for 0.3 microns. HEPA The characteristic of the net is that air can pass through, but fine particles cannot. The HEPA filter is composed of a stack of sub-glass fiber membranes that are continuously folded back and forth to form a wavy gasket to place and support the filter media.
Note: HEPA plays a vital role in the purifier. A good HEPA filter determines the price of the purifier and is usually replaced in about a year.
3. Electrostatic purification working principle: using the working principle of high-voltage electrostatic adsorption dust removal. The electrostatic type uses the working principle of high-voltage electrostatic adsorption dust removal. The cathode line in the electrostatic field generates corona discharge under the action of high-voltage static electricity, and a large number of negative ions are generated in the corona layer. The negative ions continue to move toward the anode under the action of the electrostatic field. When dust in the air passes through the electric field, the dust is charged by the collision of negative ions. The charged dust is also affected by the electrostatic field and moves toward the anode (dust collecting electrode). After reaching the anode, the charge is released. To put it simply, it uses static electricity to absorb dust!
Note: It can remove flying dust (but cannot remove poisonous gases). It is less efficient and slower than the mechanical type, and it is easy to produce ozone. This model is rated as the worst purifier in the US market. There is currently no technology in China that can prevent ozone from being generated under the action of static electricity.
4. The working principle of the photocatalyst catalysis method: When the air passes through the photocatalytic air purification device, the photocatalyst itself does not change under the irradiation of light, but it can promote chemical reactions of harmful substances in the air such as formaldehyde, Benzene and other substances are degraded under the action of photocatalysis to produce non-toxic and harmless substances, and bacteria in the air are also removed by ultraviolet light, thus purifying the air.
Note: It is broad-spectrum but requires a low air flow rate, a relatively slow purification speed and a certain amount of radiation to the human body. It is a purification method that has been eliminated in Europe and the United States.
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Formaldehyde scavenger method Working principle: It uses chemical substances and formaldehyde to carry out chemical reactions to achieve the purpose of removing formaldehyde.
1. Chemical reaction type: chemical reaction with formaldehyde to generate carbon dioxide and water, such as ammonia, etc.;
2. Biological type: made of biological agents that can react with formaldehyde, Such as urea, soy protein, amino acids, etc.;
3. Plants: made of plant extracts, such as aloe vera, tea extracts, etc.;
4. Closed: made of Made of membrane materials, forming a thin film to prevent the release of formaldehyde, such as chitosan, liquid paraffin, etc.
Disadvantages: The substances generated after the chemical reaction are likely to cause secondary pollution. Often occur in practice. The second reason why the secondary detection exceeds the standard is to absorb formaldehyde and reduce the formaldehyde content in the air without changing the chemical composition. However, this method treats the symptoms but not the root cause, and formaldehyde is easily released again.