Common air purification methods:
Physical purification methods
1. Adsorptive filtration—activated carbon
Activated carbon is a porous It has a highly developed pore structure. The porous structure of activated carbon provides it with a large surface area and can fully contact with gas (impurities), thus giving activated carbon its unique adsorption performance, making it very easy to achieve The purpose of absorbing and collecting impurities. Just like magnetism, all molecules have mutual attraction.
Disadvantages: Ordinary activated carbon cannot absorb all toxic gases, has low efficiency and is easy to desorb.
2. Mechanical filtration—HEPA network
HEPA (High efficiency particulate air Filter), which means high-efficiency air filter in Chinese, is a filter that meets HEPA standards. For 0.3 micron The efficiency reaches 99.998. The characteristic of HEPA 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.
Electrostatic purification method
Working principle: It adopts 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.
Disadvantages: It can remove floating dust (cannot remove poisonous gases), the efficiency is lower 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.
Chemical formula purification method
1 Photocatalytic method
Working principle: When the air passes through the photocatalytic air purification device, the photocatalyst itself does not change under the irradiation of light. , but can promote chemical reactions. Harmful substances in the air, such as formaldehyde, benzene, etc., are degraded under the action of photocatalysis, producing non-toxic and harmless substances. Bacteria in the air are also removed by ultraviolet light, and the air is thus Purify.
Disadvantages: Broad spectrum but requires low air flow rate, 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.
2. Formaldehyde scavenger
Working principle: It uses chemical substances and formaldehyde to carry out chemical reactions to achieve the purpose of removing formaldehyde
1. Chemical reactions: Chemically reacts with formaldehyde to generate carbon dioxide and water, such as ammonia, etc.;
2. Biological: made of biological agents that can react with formaldehyde, such as urea, soy protein, amino acids, etc.;
3. Plant type: made of plant extracts, such as aloe vera, tea extract, etc.;
4. Sealed type: made of film-forming substances, forming a thin film to prevent the release of formaldehyde. Such as chitosan, liquid paraffin, etc.
Disadvantages: First, the substances generated after the chemical reaction are likely to cause secondary pollution. In practice, secondary detection often exceeds the standard. Second, it is due to improper testing. On the basis of changing the chemical composition, formaldehyde is absorbed and the formaldehyde content in the air is reduced. However, this method treats the symptoms but not the root cause, and formaldehyde is easily released again.
3. Agent, catalytic method---cold catalyst essence
Working principle: Cold catalyst, also known as natural catalyst, is another type of air purification material after photocatalyst deodorization The new air purification material can initiate a catalytic reaction under normal temperature and pressure, decomposing a variety of harmful odorous gases into harmless and odorless substances under normal temperature and pressure, changing from simple physical adsorption to chemical adsorption, decomposing while adsorbing, and removing formaldehyde. , benzene, xylene, toluene, TVOV and other harmful gases generate water and carbon dioxide. During the catalytic reaction, the cold catalyst itself does not directly participate in the reaction. After the reaction, the cold catalyst does not change or be lost, and it plays a long-term role.
The cold catalyst itself is non-toxic, non-corrosive and does not burn. The reaction products are water and carbon dioxide, which does not produce secondary pollution and greatly extends the service life of the adsorption material.
Other purification methods
1. Water washing method
Using the siphon and centrifugal principles, the purification agent mixed with water is sucked into the motor base through the siphon principle. In the straw at the bottom of the shaft centrifugal turbine, the AC shaded pole motor rotates at high speed, and then uses the centrifugal principle to spray the purifier mixed with water into the bottle to form a layer of water film, which absorbs dust and bacteria in the air into the water. Blow purified air into the room to quickly and effectively remove toxins, dust, smoke, odor, viruses, etc. indoors, and generate a large amount of fresh oxygen.
2. Negative ion method
After contacting harmful gases floating in the air, hydroxyl negative ions can reduce pollutants from the atmosphere, nitrogen oxides, active oxygen (oxygen) produced by cigarettes, etc. free radicals), reduce the harm of excessive reactive oxygen species to the human body; neutralize positively charged airborne dust and then settle without charge, purifying the air.