In recent years, air purifiers have gradually become popular, starting from the smog that began in 2014, which has aroused unprecedented attention to air treatment and purification in the Chinese market. The purifier became a hot seller at this time.Since the first appearance of smog, media publicity has focused on particulate matter. All major brands have launched purifiers with filters to remove pm2.5, including Philips, Xiaomi, and Honeywell's purifiers. At this time, I started to sell all kinds of purifiers wildly. You will find that there are many unknown manufacturers of purifiers. They used to make clothing, sell jeans, and injection mold factories are all making purifiers. Various brand purifiers that we can see on the market now claim to be able to remove 99.9% of formaldehyde and haze.Consumers who buy purifiers only ask whether they can filter particulate matter and whether they can remove smog. This is like saying that cigarettes are designed with very good filters, which are filtered layer by layer, but no one believes that filters can filter out the carcinogens of cigarettes. Smoking is still very harmful to the body, and even causes lung cancer. The hospital's dust-free ward is clean, and the medical staff wear protective clothing, but they can't isolate SARS, Ebola and the recent coronavirus.
Filtering particulate matter is just an interception behavior, which is equivalent to cleaning the room and cleaning up the dust, but you have nothing to do with bacteria, viruses, and harmful substances, which is why the current purifier products are useless.

Filtration technology is only a kind of interception, which belongs to the physical method. It does not actively change the molecular structure of the air. In terms of dealing with smog, it is only the most elementary part of blocking particulate matter. After the particulate matter is intercepted, if you do not deal with and Decompose the particles gathered on the filter screen, then the reproduction of his bacteria and viruses is very fast. Every time you turn on the purifier, it is a secondary pollution.
The most critical issue was the bacteria and viruses carried by the smog, and no one paid attention at that time.

Air Purification  ≠  Filtering Particulate Matter

Now most families have bought purifiers, and some even bought several purifiers in one home. The understanding of purifier consumers is the filter, and the understanding of the air is the amount of particulate matter. It is believed that the purifier is only needed when there is smog, and the air needs to be purified by the filter. This is what most people think of "air purification" "understanding. And many people forget that there are several major factors for air quality:

1. Bacteria, viruses, toxic and harmful gases (including TVOC, formaldehyde, and benzene polluted by decoration)
3.The core words of particulate

air purification should be: Toxic and harmful gases, bacteria, viruses

and when we face an air problem, how to solve it, in the face of purifiers, the answer we get is uncertain:
for example, about "air purifiers that can remove formaldehyde" I googled this question, and most of the answers I found said that the purifier can't remove formaldehyde, it's all gimmicks, and some of the answers are quite fairy tales, using plants to remove formaldehyde. . . Plants are under a lot of pressure. People are just plants without even a soul. Can you just be a plant in peace?

There are basically several products on the market now:

1.The HRPA filter absorbs and filters  the particulate matter on the filter. This principle does not need to look at the big brands, and it is just a principle, fan + filter, many layers. The so-called new technology filter, high-tech filter, but he is a filter, or a net! There are many problems with this kind of purifier. If it is aimed at particulate matter, well, even if the volume is not small, more than one meter high, it is a big lump, but it needs to rely on the fan to circulate and treat the entire room, in fact, the processing capacity is not enough. . Loud noise and low power consumption.


We know that smog particles are harmful, and the filter uses limited power to absorb part of the Internet, but is this the end? All the dust particles and all kinds of smog viruses that everyone panics about are stored on the filter. They have not disappeared, no chemical changes have occurred, the smog is still the same smog, and then in a very comfortable and warm room, the humidity is also suitable. , what will happen to the large amount of dust particles on the filter. Imagine how fast bacteria multiply, so many people say that there is a smell after the filter machine is turned on, and this is the problem.
Manufacturers of purifiers, or companies, have not found a real purification method, so they came up with such a method, "filtering"
I don't know if you still remember SARS, and the new coronavirus this time in 2020. , Let all of us have a kind of powerless fear. In the dust-free ward of the hospital, the doctor wears protective clothing and gas masks. Even the best protection can not prevent infection?
General purifier detection of haze is to the number of particulate matter, but did not think, the number of particulate matter is reduced, not in the air, but in the filter particles contain harmful substances, bacteria, viruses and microorganisms, no one wants to detect this value in the past, everyone is concerned about the number of particulate matter.
Then the problems of formaldehyde, TVOC, harmful gases, and odors that we care about are not the scope of filters.

Many filter purifiers exaggerate that they remove formaldehyde. . . You show me a virus to see.

Simply put, if the filter element is not replaced regularly, it will blow the filtered pollutants back into the room again. The time to replace the filter element is difficult to grasp.
Users who have bought Honeywell purifiers have reported that the smell of the room disappeared for a while after the new machine was turned on. After turning it off and turning it on again, the smell came out again.
Therefore, filtration technology can only be called cleaning technology, not purification. The word purify should come from the verb, and it should be active purification, not passive purification.

The second way: activated carbon 



Activated carbon is also used in gas masks. Many car purifiers also use this. Generally, activated carbon is added to the filter purifier, which is said to remove formaldehyde. Activated carbon has many small pores. When the harmful gas of formaldehyde flies in, it can be adsorbed, but the problem comes again. Once the adsorption is full, the pores are occupied, and it cannot be adsorbed any more. Under humidity, activated carbon is a highly toxic carrier. (Like the filter, the problem of timely replacement)
This is also a passive purification method, just waiting for the formaldehyde to come to my bowl. . . Even if it can’t be installed, I can’t control it anymore.

The third type: photocatalyst is also called photohydrogen ion .

There are many purifiers, and it is also advertised that ultraviolet sterilization is added.
Baidu photocatalyst: Photocatalyst is a general term for photo-semiconductor materials with photocatalytic function represented by nano-scale titanium dioxide. It is coated on the surface of the substrate and under the action of ultraviolet light, it produces a strong catalytic degradation function: it can effectively degrade Toxic and harmful gases in the air; can effectively kill a variety of bacteria, and can decompose and harmless treatment of toxins released by bacteria or fungi; at the same time, it also has functions such as deodorization, anti-fouling, and air purification.


The photocatalyst has the effect of removing formaldehyde, but it is also a passive treatment. The photocatalyst needs to be sprayed on the coating, and then wait for the formaldehyde to fall on the coating to react, but. . . As long as a speck of dust or something falls on it, the formaldehyde molecules cannot touch the photocatalyst coating.
To put it figuratively, photocatalyst purification is a two-dimensional purification, which is only processed on one plane, not the entire space.
In addition, the ultraviolet light here plays a role in stimulating the photocatalyst reaction, but everyone does not know that this is to pick up sesame seeds after losing a watermelon. The high-energy-level ultraviolet light source itself generates ground-state oxygen atoms to decompose formaldehyde.

So why do you say that buying a new machine has some effect, because the passive processing, once the adsorption is full and dust falls, it is useless.
The effect is weak. (Another point that must be paid attention to, because the photocatalyst has ultraviolet light, the manufacturer will say that it contains the purification function of ultraviolet sterilization and disinfection. Be careful, because the ultraviolet light here is only designed to excite the photocatalyst, and the structure space is limited by ultraviolet light. , it has no sterilizing effect at all.)



The consumable-free purifier will also combine photocatalyst, filter activated carbon, negative ions, plus a dust collector. All kinds of filtering and adsorption principles are added together. In fact, the effect is short-lived, and it is not a fundamental solution to the problem . "Generally, this kind of electrostatic dust collector purifier comes out, or negative ions are sold on Taobao for a price of six or seven thousand, saying that no consumables are needed.

Fourth: electrostatic precipitator
electrostatic air purifiers use high-voltage electrostatic fields to adsorb fine dust and also remove nitrogen in the air. Ionization produces nitrogen oxides and compounds.
It is dangerous to use this kind of equipment to catch fire, especially in the humid environment of the south. There are many limitations, such as not being able to be used in a car.
The traditional ozone generator is also based on the same principle, using high-voltage discharge to generate ozone sterilization. It is important to note that this type of ozone ionizes nitrogen in the air and produces nitrogen oxides, which are carcinogens. (I will talk about later that the optical plasma purifier also has ozone, but we call it "active oxygen", and it smells like ozone. The composition and efficacy are completely different. The ozone produced by the light method has no carcinogens, low power consumption, and the production method is very soft.) High-voltage discharge air purifiers also have this secondary pollution problem. But now the market propaganda only greatly enlarges his role and avoids its secondary pollution.



The consumable-free purifier will also combine photocatalyst, filter activated carbon, negative ions, plus a dust collector. All kinds of filtering and adsorption principles are added together. In fact, the effect is short-lived, and it is not a fundamental solution to the problem . “ No consumables purifier ” Generally, this kind of electrostatic dust collector purifier comes out, or negative ions are sold on Taobao for a price of six or seven thousand, saying that no consumables are needed.
In fact, electrostatic dust removal is suitable for industry, not for civil use.
Baidu: a method of gas dust removal. The dust gas is separated by electricity when it passes through the high voltage electrostatic field, and the dust particles are combined with the negative ions, which are negatively charged and deposited on the anode surface by discharging. It is used to purify gas or recover useful dust particles in metallurgical, chemical and other industries. A method of collecting dust by ionizing gases using electrostatic fields so that particles are charged and adsorbed onto electrodes. In the strong electric field, air molecules are ionized into positive ions and electrons, and the electrons meet dust particles in the process of running to the positive electrode, so that the dust particles with negative charge are absorbed to the positive electrode and collected. Of course, in recent years, through technological innovation, there are also negative plate dust collection. The coal ash and dust in the flue gas are collected from the factories and power stations that use coal as fuel. Oxides used in metallurgy to collect tin, zinc, lead, aluminum, etc., are now available for household dust removal and sterilization products. Now the plasma technology, low temperature plasma technology and electrostatic dust removal are the same thing, are high voltage discharge

Fifth: On ozone:

What we now refer to as ozone in purifiers or ozone equipment: (C.F. 1840, Germany. When Shebine electrolyzed dilute sulfuric acid, he found that a special smelly gas was released, so he named it ozone. In 1785, the German people in the use of the motor, found that when the motor discharge produced a peculiar smell. It was identified as ozone by French scientist Christian Fredege in 1840.) Ozone, as it was named when it was discovered, is produced by high-voltage electrical discharges. This ozone ionizes nitrogen in the air and produces the carcinogenic nitrogen oxide, so we say that the ozone produced by the traditional ozone generator device is harmful. There is no ground-state oxygen atom and hydrogen oxygen machine in the composition of this ozone, only the role of sterilization and disinfection, for formaldehyde effect is not big.
The other kind of ozone, which we call natural ozone, is produced by ultraviolet radiation, and we humans are protected by the ozone layer. In the air is very good forest seaside, ozone content is relatively high, the air is fresh.
And the photoplasma purification technology is to imitate the purification principle of nature, using ultraviolet to produce ozone. It's very pure, and this kind of ozone we call "reactive oxygen species."
So, please note: "Ozone" and "reactive oxygen species" are two different concepts. The former is produced by high-voltage discharge, while the latter mimics the natural environment, where ultraviolet light produces ozone.
Sixth: negative ion technology

The concentration of negative ions in the air is one of the indicators of air quality. The World Health Organization has also made relevant regulations on the standard concentration of negative ions in fresh air. Negative ions have also been brought into the meteorological monitoring system in China and are widely used in the field of air environment protection.
We in the waterfall, the forest, lightning rain can usually feel the air is very fresh, this is because the air contains a large number of negative ions. Crystal GYPSUM LAMP CAN send out natural ANion this KIND OF CHARACTERISTIC, IN the heated state and close the room, especially sufficient, can effectively balance the content of positive and negative ions in the air.
Negative ion is called "air vitamin", its role includes: in addition to the dust, in addition to the floating hair, in addition to the peculiar smell, in addition to smoke, sterilization, purify air, treatment of spore pollen, dust, pet hair, allergies, improve asthma and other respiratory diseases, improve the mood swings, depression, chronic fatigue, relieve mental stress status and so on. In short, it is good for people's health, mood and energy.
Through the artificial negative ion generation technology to generate ecological grade small particle size air negative ions, simulate the nature of lightning high pressure ionized air to generate negative electrons, with oxygen, carbon dioxide in the air as the carrier of transmission.

Our photoplasma purifier also has a negative ion addition. It can be used as an auxiliary cleaning effect, but many purifiers, only rely on the purification effect and ability of negative ions is not enough.

Seventh type: Ultraviolet technology
Ultraviolet disinfection is the use of appropriate wavelength of ultraviolet light can destroy the molecular structure of DNA (deoxyribonucleic acid) or RNA (ribonucleic acid) in microbial body cells, resulting in growth cell death and (or) regenerative cell death, to achieve the effect of sterilization. Ultraviolet disinfection technology is based on modern epidemic prevention, medicine and photodynamics, using specially designed high efficiency, high intensity and long life UVC band UV light irradiation water, water bacteria, viruses, parasites, algae and other pathogens directly killed.


Now there are also some air disinfection machines on the market, or ultraviolet lamp sterilization device, the more commonly used ultraviolet lamp sterilization in hospitals is usually understood. This is quite different from the optical plasma technology. Most UV lamps used in hospitals use the 254 band. Borinated glass material, low cost, low UV transmittance. The service life is usually several hundred hours, and the ultraviolet attenuation is also fast.
A lot of purifiers have UV lights in them to make them more attractive.
However, the application of UV technology is very difficult, and there are few mature applications in China and even in the world.
Many purifiers add UV, which is a very cheap UV lamp, and the design structure can not play the effect of UV.
Usually the traditional ultraviolet technology is through direct irradiation sterilization, and the next to say "photoplasma technology" is also UV technology, but the difference is very big.

The eighth purification technology: optical plasma technology:

The reason why it is called photoplasma technology, not UV purifier, is because it uses the principle of light to purify, rather than through direct irradiation to kill the virus purification. It is the principle that different wavelengths of ultraviolet light are combined to produce plasma that is disseminated into the air to actively decompose harmful gases. So it's technically difficult, it's a complicated optical design.
The application of ultraviolet technology in air purification products, only a few enterprises in the world have this technology. Because of its technical difficulty, complex design structure and high requirements on internal parts, the cost is also dozens of times higher than that of ordinary purifiers.

The UV core component of optical plasma energy level is very high, different from ordinary UV lamp, so the inside of the purifier is all made of metal stainless steel protective cover, the inside of the casing is also made of electroplating coating process. There's no need to worry about UV leakage or radiation. All you see through the vents is the reflected light from the metal shield. Ultraviolet technology is both an old technology and a new technology, but it is also a double-edged sword. To use it well requires cutting-edge technology that can handle it. It's not easy to solve a lot of the technical problems.

The scientific explanation of photoplasma

Photoplasma (PurifyingPhoto Plasma)
It is an advanced oxidation degradation technology formed by advanced photochemical reaction technology. Photoplasma has the following energy components:
Dual wavelength (UVC, UVD) ultraviolet light + (photoelectric activation) → pure ozone (O3) + atomic oxygen (O) + ground state oxygen (O*), through two wavelengths of special ultraviolet light source, can produce a series of intense sterilization of light, electric plasma cluster, collectively known as light plasma.
The main elements of all organic pollution (bacteria, viruses, formaldehyde, ammonia, benzene, TVOC, etc.) are H and C (carbon and hydrogen). The molecular structure is relatively stable. The basic principle of purification and degradation by light plasma is: In a specific wavelength (UV C) and a specific intensity of UV radiation light under the organic matter (hydrocarbons) photosensitive process, that is, the molecular absorption of a specific wavelength of photon energy of organic compounds, molecular chains are torn, decomposed into ions, free atoms, excited molecules or neutral molecules; At the same time, under the irradiation of specific wavelength (UV D) and specific intensity of ultraviolet radiation light, oxygen molecules in the air (O2) will become ozone (O3) and atomic oxygen (O), ground state oxygen (O*) after absorbing photon energy; The chemical properties of these elements are very active, with a strong oxidation effect, is a strong oxidant, can be photosensitive decomposition of organic matter all oxidation, into water vapor (H2O) and carbon dioxide (CO2) and other volatile harmless gases, to achieve the purpose of thorough removal of pollutants. Compared with other traditional purification methods, this purification result is clean, thorough, no residue, and will not bring secondary pollution.

To sum up, the real air purifier, in order to solve the problem of air, is not only to intercept and filter particles, but also to take into account the bacteria, microorganisms, toxic and harmful gases to be able to deal with, is the real air purification, how to choose the right product, has been related to everyone's health problems.   
Of course, to really solve the air problem, the best solution should ultimately be a more perfect air purification system, the perfect combination of various purification technologies, in order to achieve the most ideal use effect. 
Analysis and comparison of air purification technologies currently on the market