(1) Electrostatic purification mode
 
Working principle: Adopt the working principle of high voltage electrostatic adsorption dust removal. Electrostatic type is the working principle of high voltage electrostatic adsorption dust removal. Under the action of high voltage static electricity, the cathode wire in electrostatic field produces corona discharge, and a large number of negative ions are produced in corona layer, which continuously move to the anode under the action of electrostatic field. When the dust in the air passes through the electric field, the dust is charged by the collision of negative ions, and the charged dust also moves to the anode (dust collecting pole) under the action of electrostatic field, and releases the charge after reaching the anode.
 
Disadvantages: It can remove floating dust (can't remove toxic gas), its efficiency is lower and slower than mechanical type, and it is easy to produce ozone. This model is rated as poor purifier by American market.
 
 
 
(2) Physical purification mode
 
 
 
1. Adsorptive filtration-activated carbon
 
Activated carbon is a kind of porous carbon-containing material, which has highly developed pore structure. The porous structure of activated carbon provides a large amount of surface area for it, and can fully contact with gas (impurities), thus endowing activated carbon with unique adsorption performance, making it very easy to absorb and collect impurities. Just like magnetic force, all molecules have mutual attraction.
 
Disadvantages: Ordinary activated carbon can not adsorb all toxic gases, which is low in efficiency and easy to desorb.
 
 
 
2. Mechanical filtration-HEPA net HEPA (High Efficiency Particular Air Filter), which means high efficiency air filter in Chinese, has an effective rate of 99.998% for 0.3 microns. The characteristic of HEPA net is that air can pass through, but fine particles cannot pass through. HEPA filter screen is composed of a stack of sub-glass fiber membranes continuously folded back and forth, forming wavy gaskets for placing and supporting filter materials.
 
 
 
(3) Chemical purification mode
 
 
 
1. Photocatalytic method
 
How it works: When the air passes through the photocatalytic air purification device, the photocatalyst does not change itself under the irradiation of light, but the harmful substances in the air, such as formaldehyde and benzene, which can promote the chemical reaction, are degraded under the action of photocatalysis to generate non-toxic and harmless substances, and the bacteria in the air are also removed by ultraviolet light, thus purifying the air.
 
Disadvantages: Broad spectrum but requires low air flow rate, slow purification speed and certain radiation to human body, which is the purification method eliminated in Europe and America.
 
 
 
 
 
2. Formaldehyde scavenger
 
Working principle: It uses chemical substances and formaldehyde for chemical reaction to achieve the purpose of removing formaldehyde.
 
2.1. Chemical reaction: Chemical reaction with formaldehyde to generate carbon dioxide and water, such as ammonia water;
 
2.2. Biology: Made of biological agents that can react with formaldehyde, such as urea, soybean protein, amino acids, etc.;
 
2.3. Plants: Made of plant extracts, such as aloe and tea extracts;
 
2.4. Sealing: Made of film-forming substances, forming a film to prevent formaldehyde release, such as chitosan and liquid paraffin;
 
Disadvantages: First, the substances generated after the chemical reaction are likely to bring secondary pollution, and the phenomenon that the secondary detection exceeds the standard often occurs in practice.
 
Second, it absorbs formaldehyde on the basis of not changing the chemical composition and reduces the formaldehyde content in the air. However, this way treats the symptoms but not the root causes, and formaldehyde is easy to be released again.
 
 
 
3. Medicament and Catalytic Method-Working Principle of Cold Catalyst Essence: Cold catalyst, also known as natural catalyst, It is another new air purification material after photocatalyst deodorization air purification material, Can catalyze the reaction at normal temperature, Under normal temperature and pressure, various harmful odorous gases are decomposed into harmless and tasteless substances, From simple physical adsorption to chemical adsorption, it decomposes while adsorption, removes harmful gases such as formaldehyde, benzene, xylene, toluene and TVOV, and generates water and carbon dioxide. In the catalytic reaction process, the cold catalyst itself does not directly participate in the reaction, and after the reaction, the cold catalyst does not change or lose, and plays a long-term role. The cold catalyst itself is non-toxic, non-corrosive and non-burning, and the reaction products are water and carbon dioxide, which does not produce secondary pollution and greatly prolongs the service life of adsorption materials.
 
 
 
(4) Other purification methods
 
1. The water washing method uses siphon and centrifugal principle, The purifying agent mixed with water is sucked into the straw at the lower part of the coaxial centrifugal turbine of the motor base through siphon principle, Through the high-speed rotation of the AC shaded pole motor, Then, according to the centrifugal principle, the purifying agent mixed with water is sprayed into the bottle liner to form a water film, which inhales dust and bacteria in the air into the water, and blows the purified air into the room at the same time, so as to quickly and effectively remove toxic organisms, dust, smoke smell, odor, viruses, etc. in the room and generate a large amount of fresh oxygen.
 
 
 
2. The negative ion method can reduce the active oxygen species (oxygen free radicals) produced by atmospheric pollutants, nitrogen oxides, cigarettes, etc. after contacting with harmful gases floating in the air, and reduce the harm of excessive active oxygen species to human body; Neutralize the positively charged air dust and settle after no charge, so that the air can be purified.