Glossary

Photocatalysis is the process by which chemicals, bacteria, viruses or dust micro particles are broken down by a photocatalyst and light radiation. Many substances decompose naturally and spontaneously by the action of light, photocatalysts are substances that speed up this process.

Photocatalysis is therefore a process of chemical decomposition of substances in the presence of a photocatalyst and light radiation. It is based in principle on photolysis, the natural decomposition of some substances by the action of light, accelerated by the presence of a photocatalyst. If a material with photocatalytic properties is exposed to light from a suitable wavelength, its surface is activated and a characteristic reaction is triggered. The primary free electron-hole pair and the hydroxyl radicals secondary to the contact of the excited photocatalyst molecule and the water vapor decompose the organic and inorganic substances present.

Substances decomposable by photocatalysis include, for example:. nitrogen oxides, sulfur oxides, carbon monoxide, ozone, ammonia, hydrogen sulfide, chlorinated hydrocarbons, dioxins, chlorobenzene, chlorophenol, simple hydrocarbons, aromatic hydrocarbons (benzene, phenol, toluene, ethylbenzene), pesticides, etc. viruses, fungi or micro-dust particles. The final product is usually common and stable compounds. The specific industrial applications of the photocatalysis principle may differ mainly in the type of the catalyst. Titanium dioxide, which is activated by UV radiation, is most often used.

The use of photocatalysis is done in two basic areas:

• self-cleaning - thanks to photocatalysis, the surface of the material is resistant to the development of organic impurities and thus retains its original appearance and colour for a long time
• Cleaning the surrounding media - polluted air or water allows you to suppress some of the adverse effects of human activity, for example air pollution in densely populated areas.

The two areas of use are very closely related - these are actually only two somewhat different consequences of the same reaction. In the case of self-cleaning, however, the emphasis is on decomposition of solids adhering to the surface of the material, while in the case cleaning the surrounding media, the ability to decompose a particular substanceconsidered undesirable near the surface.

The plasma system is an additional feature of Airbi purifiers and humidifiers, which helps eliminate viruses in the air. It works as follows:

The device uses high voltage to form positive and negative ions (Fig. 1), which form clusters (Fig. 2). These ions are surrounded by water molecules that ensure their longevity. The clusters of ions then surround the airborne viruses (Fig. 3), attaching to them and forming highly reactive molecules, so-called hydroxyl radicals (OH). They remove the hydrogen from the virus surface (Fig. 4), which disrupts the surface membrane of the virus, which dies immediately (Fig. 5). The removed hydrogen is subsequently combined with a hydroxyl radical and the final product is water.(H₂0) (Fig. 6).

In short: formed clusters of ions attack the surface of viruses until they are harmless. The plasma system is absolutely safe, its only by-product is water.

There are several technological options to choose from today to humidify the indoor air.

NATURAL EVAPORATION

This method is based on the natural principle of water evaporation in nature. The water sticks to the surface of the rotating disks or soaks into the filter paper and rises upwards. The fan is used to direct the flow of dry air through these filters. This makes the water evaporate into the air faster and easier.  It is not possible to saturate the air with water vapour by cold evaporation. Unlike other principles (ultrasound, thermal evaporation), no emitted steam is visible with this method of humidification.

A special category in natural evaporation is air washers. These are a combination of a purifier and a humidifier operating on a principle similar to cold evaporation. Special evaporator discs absorb (bind) water, while the fan blows dry air through these humidified rotating discs. The humidified air is then dispersed into the surroundings. Humidifiers working on this principle are high-performance devices that have low operating costs and are almost silent.  A significant advantage of these devices is the fact that they clean the air from hazardous particles in the air and, if equipped with other technologies for air purification (e.g. PLASMA system nebo HEPA filter), they can be a full-fledged air purifier replacement.

ULTRASOUND

The vibrating membrane (piezo) uses ultrasonic technology to decompose the water into micro droplets, which are then dispersed into the air by means of a fan, where they evaporate. The visible steam is cold and harmless to health.  Ultrasound devices do not require as much electrical energy and have sufficient power. When water vapour is generated by ultrasound, minerals are also released into the air, so it is necessary for devices with this technology to be equipped with water filters. Even in the case of hard water, this principle can lead to the deposition of mineral dust on the furniture and other equipment in the room.

HEAT EVAPORATION

The water inside the appliance heats up until water vapour is generated without bacterial germs (they are destroyed by high temperatures). The steam spreads in all directions in the room and increases the relative humidity of the air very effectively. These humidifiers are highly productive and should therefore always be equipped with a hydrostat for humidity control. But when it comes to security, it's worse. There is really hot steam coming out of the device, and therefore these devices are not suitable for places where children or animals are present.  In addition, the heating elements become clogged with lime scale over time, and regular maintenance is required.