Ventilation method does not need too much explanation, that is, it discharges harmful gases to the outside through the flow of air. This is a simple and effective method. The only drawback is that the formaldehyde release cycle is long, usually three to fifteen years. It is obviously unrealistic to leave the new house idle for more than three years after renovation. Because of this, ventilation alone cannot meet the requirements.

2, formaldehyde scavenger or formaldehyde dissolving enzyme

Formaldehyde scavenger "removes" formaldehyde through chemical reaction, the essence of which is to reduce the toxicity of the target substance or convert it into non-toxic substance. Formaldehyde can be oxidized to formic acid or reduced to methanol. Although the toxicity and irritation of these two substances are lower than formaldehyde, their toxicity still exists. For example, some highly oxidizing formaldehyde scavengers can oxidize formaldehyde, but they are easy to decompose by themselves. Spraying on the board will damage the wood, and it will be ineffective within a few hours. It is impossible to "spray it to the end". In addition, the high concentration scavenger sprayed in the air will cause new pollution hazards to people. Other oxidants and reductants can not effectively remove formaldehyde, and will also introduce similar new pollution.

For some businesses, the principle of formaldehyde-dissolving enzyme to remove harmful gases by infiltrating into plates is even more unreliable. Many plates are produced under high humidity and high pressure, and the surface is often crusted. How does formaldehyde scavenger penetrate into the room?

3. Activated carbon adsorption

Teacher Li, who specializes in activated carbon at Nankai University, said that the initial use of activated carbon did have an impact, because the pores had adsorption potential, which was formed by the attraction between carbon molecules and adsorbed molecules. The smaller the aperture, the stronger the adsorption potential. In addition, according to the theory of molecular motion, all objects are composed of molecules or atoms, and there are gaps between them, and at the same time they are in an endless state of random thermal motion, and molecules collide frequently. According to relevant data, in the standard state, the free movement speed of formaldehyde molecule is about 450m/s, and one formaldehyde molecule collides with other molecules 109 times per second. At this time, if the diameter of the collision molecule matches the pore of the activated carbon, it is adsorbed. Whether it is traditional activated carbon or modified activated carbon, the adsorption capacity is limited because of too large pores.

Teacher Li denied the market statement that activated carbon can be reused after a period of use. He thinks. "The highest temperature of sunlight is only about 50 degrees Celsius, and only water can evaporate. The pollutants adsorbed by activated carbon cannot be completely volatilized, and the adsorption function of carbon cannot be completely restored. "

Many products are advertised to remove formaldehyde quickly and efficiently. For example, a brand of activated carbon can "remove 92.9% of formaldehyde in 6 hours ..." Teacher Li thinks there is a serious exaggeration. "It's impossible. Activated carbon is passively adsorbed through pores, and its adsorption of harmful substances in the air must rely on air as a medium. However, indoor air mobility is poor, so it is difficult for activated carbon to adsorb harmful substances in the air to far places in a short time, and it takes 3 to 15 years for formaldehyde in home decoration to be removed. How can it have such a great removal effect? Because the adsorption capacity of activated carbon itself is limited, formaldehyde in furniture such as plates is constantly released, and many consumers do not feel the effect after using activated carbon, which is the reason. Consumers who want to live in a new house early, activated carbon can't solve the problem. "

In addition, the shelf life of activated carbon can reach 5-8 months on the premise that it can be reused as advertised by merchants, which is debatable. "Three months is terrible. Under the premise of placing 1 kg of activated carbon per 10 square meter, the adsorption capacity of activated carbon will become weaker and weaker after one month."

4. Soak in water, vinegar and black tea to remove formaldehyde.

Many people on the Internet say that because formaldehyde is soluble in water, you can put more pots at home to absorb formaldehyde, or soak it in vinegar or black tea.

It is a fact that formaldehyde is soluble in water, water, alcohol and ether. Free formaldehyde in the air will dissolve in water during exercise, which is basically the same as the adsorption principle of activated carbon. The contact area between a basin of water and air is only the size of a basin, while the specific surface area of internal pores of 1g activated carbon can reach the size of a football field. Even if you put a hundred pots of water in the room, the adsorption effect will not be much stronger than a small bag of activated carbon. Therefore, it is obviously unrealistic to use water, black tea and vinegar to adsorb formaldehyde.

The release of formaldehyde is closely related to indoor temperature and temperature. With the increase of humidity in the air, the release of formaldehyde will greatly increase. The experimental results show that when the relative temperature in the air increases 10%, the indoor formaldehyde emission will increase by about 5%.

In fact, using water, vinegar and black tea to soak in water to absorb formaldehyde will make your formaldehyde content higher.

5, photocatalyst to remove formaldehyde

Under the irradiation of light, photocatalyst will produce a photocatalytic reaction similar to photosynthesis, producing free hydroxyl and active oxygen with strong oxidation ability. It has a strong redox function, can oxidize and decompose various organic compounds and some inorganic substances, can destroy the cell membrane of bacteria and solidify the protein of viruses, can kill bacteria and decompose organic pollutants, and can decompose organic pollutants into pollution-free water (H2O), carbon dioxide (CO2) and other harmless substances, so it has a strong sterilization and deodorization effect.

Theoretically speaking, photocatalyst is a kind of in addition to formaldehyde product with the highest quality, but in fact, in order to play its role, photocatalyst needs ultraviolet excitation, so it is impossible to have ultraviolet rays all the time in the room, especially in some drawers and cabinets where formaldehyde is released most seriously, and there is no light. This limits the role of photocatalyst.

6. Fruits such as oranges and pineapples adsorb formaldehyde.

This is a method that many people like to use in the past, and it can be said to be a folk law. Many folk indigenous laws are the summary of long-term life experience and the truth that has been tested by time and practice. But this method is completely absurd. CCTV Financial Channel "Is it true?" The column just broadcast a program, grapefruit peel and pineapple remove formaldehyde? Is it true?/You don't say. /You don't say. The experiment was specially done in the program. The experimental results showed that the formaldehyde content of the experimental warehouse with grapefruit peel was ten times that of the blank warehouse in the same sealed warehouse. Because after putting grapefruit peel, the temperature of the experimental warehouse rises, and the amount of formaldehyde released greatly increases. Pomelo peel and pineapple can not only remove formaldehyde, but also increase indoor formaldehyde content.

In the past, many people thought that after using grapefruit peel and pineapple, the taste of interior decoration was small, because the taste of fruit masked the smell of formaldehyde.

8. Plants absorb formaldehyde

Plants can inhale some harmful substances through photosynthesis, but the effect of this method is extremely limited. The reason for this is the following：

1), plants usually inhale some harmful substances during the day, but they don't have this function at night. The law of people's life is generally outdoor during the day and indoor at night. When people need air purification most, plants can't play a corresponding role.

2) The harmful substances absorbed by plants are extremely limited. The national standard requires that the formaldehyde emission value is less than 0.08 mg/m3, and the formaldehyde in most newly decorated houses is not less than 0.2 mg/m3, while the formaldehyde absorbed by the high formaldehyde absorption efficiency is only 20 micrograms per hour. A room of 100 square meter, with a height of 3 meters, a formaldehyde value of 0.2 mg/m3, and 1.800 pots of green radish. Before formaldehyde is reduced to 0.08 mg, almost the whole room space needs to be filled, which is still carried out under the condition of sufficient sunlight, and it is necessary to ensure that formaldehyde is not released during absorption. In fact, formaldehyde has been continuously released from the renovated furniture. Therefore, plants can only play an auxiliary role in controlling harmful substances such as formaldehyde and benzene.

9, vinegar fumigation

Vinegar is an acidic substance, which can slightly neutralize ammonia in the air, but will not react with other harmful components such as formaldehyde.

10, Maya Blue in addition to formaldehyde

Maya blue is an adsorbent made of rare earth, which is known as "industrial vitamin". It is a strategic material of China, and its export is strictly restricted. It is an essential raw material for making all kinds of high-tech products. In developed countries, the purification and adsorption capacity of rare earth has been applied many years ago, while China has only started to apply it in recent years. Maya Lan is one of the typical representatives.

Maya blue is made of rare earth materials, purified at high temperature and dispersed by ultrasonic wave. It has a unique microcrystalline structure, natural nano-scale lattice gap, high specific surface area (a large number of pores), high permeability and polar pore surface. The pore size of its internal pores is between 0.27 and 0.98 nm, showing crystal arrangement. At the same time, it has weak electricity, and the molecular diameters of formaldehyde, ammonia, benzene, toluene and xylene are all between 0.4 and 0.62 nm, and they are all polar molecules, so it has the characteristic of preferentially adsorbing harmful gases such as formaldehyde, benzene and TVOC, achieving the effect of purifying indoor air, and its natural characteristics will not cause secondary pollution.

However, due to the high price of raw materials, its wide use is limited.