There are four types of filters used in household air cleaners. According to the principle of operation, they can be divided into: dust, ionization (electronic) filter, adsorption and photocatalytic filter. Most often, in modern air cleaning equipment for air filtration two, and sometimes three types of filters are installed at the same time.
Dust filters for air filtration. h3>
Dust filters are a special fabric made of various fibers that can trap dust particles ranging in size from 0.3 microns and above. The principle of their operation is quite simple: the air is driven through the fabric by a fan and thereby freed from dust particles. The technology of using dust filters in industrial and domestic air cleaners is widespread in the West and is called HEPA (High Efficiency Particulate Air). This principle of dust collection is also used in air cleaners manufactured by Bionaire (Canada) and Honeywell (USA). In Russia, this is Petryanov's fabric.
+ Ease of use, average cost.
- Cleaning only from medium-dispersed dust particles, volatile environmental pollutants remain in the air, high operating costs.
Ionizing cleaners for air filtration
Ionizing cleaners, or electrostatic precipitators, clean the air well from dust and soot, absolutely not freeing from such toxic pollutants as carbon monoxide, nitrogen oxides, formaldehyde and other harmful organic compounds present in the air of domestic and industrial premises. In addition, during operation, ionization cleaners themselves generate nitrogen oxides and the extremely dangerous ozone gas, which is 5 times more toxic than carbon monoxide. The reason for the formation of ozone is the use of an electrical voltage of several thousand volts in the ionization chamber of an air-cleaning device. Ionization filters are used in a number of models of air cleaners manufactured by Bionaire (Canada) and Honeywell (USA). Today, on the domestic market, there are household models of air cleaners equipped with ionization filters from Daikin (Japan) and the Russian Super Plus model. It should be noted that when using the "Super-Plus" air cleaner, ozone appears in the atmosphere of the room almost immediately after the start of its operation, i.e. even with an uncontaminated "ground electrode". The air-cleaning devices that use the principle of air ionization include the Chizhevsky Chandelier, which is popular in our country. Its difference from the above-mentioned ionization filter is that the precipitating surface in the air cleaning circuit is the ceiling and walls of your apartment. This principle of air purification from dust would be indispensable in a coal mine, but in the case of a “room with a white ceiling”, the results of this air cleaner will not be slow to appear in the form of a black spot over the “Chandelier”.
+ Low cost, lack of replaceable filters.
- Cleaning only from dust particles, organic and toxic pollutants remain in the air atmosphere.
- During the operation of air cleaning devices, nitrogen oxides and an extremely dangerous gas, ozone, are generated .
Adsorption carbon filters for air filtration.
Adsorption carbon filters trap almost all toxic air impurities with a molecular weight of more than 40 atomic units. However, studies and practice of using adsorption carbon filters have shown that coal practically does not adsorb light compounds, which include such typical urban air pollutants as carbon monoxide, nitrogen oxides, formaldehyde. Thus, air cleaners using carbon filters turned out to be ineffective for cleaning the air of urban premises from its main environmental pollutants. A significant disadvantage of any adsorption filters is their limited capacity, and if the adsorbent is not replaced in time, they themselves become a source of toxic organic substances and pathogenic bacteria that pollute the environment. Adsorption filters are used in Philips (Holland) and Honeywell (USA) devices, as well as in a number of domestic air cleaning systems.
+ Captures almost all toxic impurities with a molecular weight of more than 40 atomic units, captures dust well.< /p>
- Not effective for the main environmental pollutants of urban air.
- High operating costs.
- If the filters are not changed in time, the air cleaner becomes a source of harmful substances.< h3>Photocatalytic purifiers for air filtration.
The invention of the photocatalytic "filter" - a revolutionary product that has no analogues - has given a fundamentally new approach to air purification and creating comfortable conditions in the premises. In fact, a photocatalytic “filter” is not a filter, since it does not retain harmful impurities from the air stream, but decomposes them into harmless gaseous components of clean air on the surface of a photocatalyst excited by ultraviolet radiation.
The main significant advantages over other known systems filtration (HEPA type, mechanical, carbon, electrostatic) are as follows: a) In the process of photocatalysis, harmful impurities do not accumulate in the filter, and under the action of ultraviolet radiation in the presence of a photocatalyst they decompose to absolutely harmless components of the natural air environment. b) The size of the destroyed particles - up to 0.001 microns! This value is comparable to the size of viruses and molecules and is the physical minimum that can be achieved in principle. c) Unlike other systems, photocatalysis removes all harmful impurities from the air, incl. from viruses, bacteria and gas pollution. At the same time, the purification efficiency from the latter is 500 times higher than that of carbon filters! The cleaning efficiency has a consistently high rate, independent of the filter output. Photocatalytic cleaners are designed for continuous operation with simultaneous presence of people, without adversely affecting the human body, which is confirmed by objective experimental and scientifically based works in domestic and foreign literature. They are distinguished by an almost unlimited resource and a wide spectrum of action, destroying almost any pollutants, they have highly effective microbactericidal and sterilizing activity.
Two companies using this method are represented on our market:
Japanese concern Daikin manufactures and sells ACEF3AV1-C(H) and MC401VE purifier in Russia, which is equipped with a mechanical filter for cleaning coarse dust, an ionization filter for trapping fine dust, and a photocatalytic filter for decomposing molecular impurities. But with all this, it has a number of disadvantages: high cost and a very low degree of purification per pass (less than 2%).
In Russia, the Information Technology Institute has developed household photocatalytic air purifiers of the Aerolife ™ brand, mass-produced Aerolife Firm LLC, which are superior to foreign counterparts in a number of parameters (the degree of purification per pass is at least 30% + low cost), which makes them especially attractive to Russian consumers. To excite the photocatalyst, radiation in the UV-A range (360nm) is used, which does not generate gas ionization and does not have a harmful effect on humans. The advantages of the method include the fact that the photocatalyst copes well not only with any organic pollutants, but also with formaldehyde, carbon monoxide, ozone, nitrogen oxides - just with the main urban air pollutants, precisely with those that other filters “do not notice”. The device also kills bacteria, viruses and fungal spores, decomposing them into harmless components: carbon dioxide and water.
+ Practically unlimited resource at low operating costs.
+ Effective for almost any pollutants, has a highly effective microbactericidal and sterilizing activity. + Designed for continuous operation with simultaneous presence of people.
+ Purifiers are not a source of hard UV radiation, ozone, nitrogen oxides, do not accumulate toxic components and do not require periodic replacement and disposal of the absorbent.
- With a long inactivity of the device, the activity of the catalyst decreases, so it is necessary that the device work continuously.