Air purification refers to providing overall solutions such as sterilization, disinfection, dust reduction, haze removal, removal of harmful decoration residues, and odors for various indoor environmental problems, to improve living and office conditions and enhance physical and mental health.

Main indoor environmental pollutants and pollution sources:

TVOC detection sensors: Radioactive gases, mold, decoration residues, carbon dioxide;

Dust sensor: Particulate matter, second-hand smoke, etc.

Definition of Air Purifier: An electrical device that has a certain ability to remove solid pollutants and gaseous pollutants from indoor air;

Increasingly mature air purification technology

An air purifier that can remove two or more types of air pollutants is called a multi-functional indoor air purifier.

Pollutants mainly refer to bacteria, viruses, solid pollutants (such as dust, pollen, bacteria-carrying particles, etc.), and gaseous pollutants (odors, decoration pollution such as formaldehyde) in indoor air.

European and American countries focus more on the sterilization and disinfection functions of air purifiers, while in China, due to the severe haze in recent years, more attention is paid to removing particulate matter (dust reduction).

According to the principle of action, they are mainly divided into active purification and passive purification. According to different pollutants:

1. Solid pollutant removal type: Mainly includes mechanical filtration, electrostatic dust collection, electrostatic electret, negative ions, and plasma method filtration. Among them: mechanical filtration, electrostatic dust collection, and electrostatic electret are passive purification (filtration), which only filters the air passing through the filter material; negative ions and plasma method filtration are active purification (filtration), where the purifier actively releases purification factors for air purification.

2. Gaseous pollutant removal type: Removes harmful decoration residues such as formaldehyde and benzene, mainly using two technologies: catalytic decomposition and activated carbon adsorption. The principle of catalytic decomposition is to use its strong oxidizing property to react with carbonyl (carbon-oxygen) and hydrocarbon (carbon-hydrogen) compounds such as formaldehyde (HCHO) and benzene (C6H6) to generate CO2, H2O, O2, etc., thereby completely eliminating the aforementioned harmful residues.

The technologies used by air purifiers currently on the market mainly include the following:

1. HEPA Filter: High-Efficiency Particulate Air, referred to as HEPA. It is divided into five materials: PP filter paper, glass fiber, composite PP PET filter paper, melt-blown polyester non-woven fabric, and melt-blown glass fiber, which can filter particles of specific sizes. HEPA-standard filters are widely used, from medical equipment, cars, airplanes to homes. The filter standard is set by the U.S. Department of Energy. For particles with a diameter of 0.3μm, the filtration efficiency is about DOP 99.97% or more. Commonly used high-efficiency filters can achieve an interception efficiency of 99.99%. The advantage of HEPA is mature technology and, because it uses physical filtration, it does not cause secondary pollution. The disadvantage is that HEPA has high air resistance and high requirements for fans; the higher the grade of HEPA filter, the greater the air resistance. Another issue is the maintenance cost that users are more concerned about. Since the air quality in Beijing and other places is much lower than in Western countries, the service life of HEPA filters can only last about half a year, and replacement is expensive. Furthermore, there is no corresponding recycling mechanism in China, causing environmental pollution.

2. Electrostatic Dust Collection: We all know the principle of opposite charges attracting each other. Ion wind technology generates airflow by driving charged particles through electrostatic field force. Charged particles are attracted and captured by electric field force when entering the charged dust collection plate. Such products can work very quietly because they do not require a motor. The advantage of this technology is no subsequent maintenance cost, as the dust collection plate can be wiped directly. However, the more prominent disadvantage is that the maximum CADR (Clean Air Delivery Rate) value of products using this technology is around 40, which is a huge gap compared to HEPA filters. In addition, existing technology inevitably generates ozone during the air ionization process. The harm of ozone cannot be ignored, which poses a significant challenge in balancing ozone concentration and improving product efficiency and performance.

3. Activated Carbon: Activated carbon is made from carbon-containing substances such as sawdust, fruit shells, and lignite through carbonization and activation. There are two types: powder (particle size 10-50 microns) and granular (particle size 0.4-2.4 mm). General properties are porous with a large specific surface area. The total surface area reaches 500-1000㎡ per gram. The purification effect of activated carbon is directly related to the pore size. When the pore size is close to the particle diameter, the purification effect is most obvious. Coconut charcoal is a new type of activated carbon with a smaller pore size, making its purification effect more significant.

4. Catalytic Technology: Japanese scientists first discovered that TiO2 single-crystal electrodes under light can decompose water, and photocatalytic technology was put into use in the 1990s. When air and water pass through the photocatalyst material unit, a large amount of hydroxide ions OH, peroxyhydroxyl radicals HO2, peroxide ions O2, and hydrogen peroxide H2O2 are generated through redox reactions. These ions diffuse in the air, sterilizing and disinfecting by destroying bacterial cell membranes and coagulating virus proteins, decomposing various organic compounds and some inorganic substances, and removing harmful gases and odors. Experimentally proven photocatalytic sterilization mechanisms include: cell osmosis, destruction of Coenzyme A, degradation of endotoxins, denaturation and decomposition of proteins and lipids, and cell mineralization.

The pm2.5 sensors required for air purifiers are also becoming increasingly mature.

PM2.5 sensors required for air purifiers, Luftmy PM2.5 sensor application areas: air purifiers, air conditioners with purification function, PM2.5 detectors, range hoods, smoke alarms, fresh air systems, dedicated PM2.5 sensors, air detectors, etc.