Moving into a new home that has just been renovated is considered a great joy in life, but the “formaldehyde pollution” that is being talked about everywhere makes people’s hearts tighten. What to do? Various tips: buy a few large bags of bamboo charcoal in the house, it is said that this thing can not only adsorb odors, there are special effects on the invisible formaldehyde; plant a few pots of green plants in the house, especially hanging orchids, the ability to absorb formaldehyde that is called a strong. Bamboo charcoal, green plants? Rely on them to remove formaldehyde, can be effective?
Bamboo charcoal Vs. formaldehyde: adsorption not absorption
Some advertisements claim that bamboo charcoal has a strong adsorption capacity for formaldehyde, and claim to have experimental evidence to support. However, these experimental conditions can not let people doubt, they are placed in the nearly saturated formaldehyde vapor bamboo charcoal, per gram of bamboo charcoal up to 68 mg of formaldehyde adsorption is measured in this state, such an environment, just throw into a piece of wood can also be smoked into the smell of formaldehyde. The key question is whether bamboo charcoal can lock these formaldehyde, the experimental results are disappointing. Once the bamboo charcoal, which was full of formaldehyde, was put into an empty room without formaldehyde pollution, the formaldehyde on it would be released rapidly, and the formaldehyde content in each gram of bamboo charcoal could drop to 34 mg within 3 hours, and to 1.6 mg after 1 day – the decontamination product became a source of pollution all of a sudden. [1] Wang Jun t, Intensive Care Unit, Nanping City First Hospital
The so-called adsorption capacity of bamboo charcoal is mainly due to the fact that this indefinite carbon (distinguished from the diamond kind of crystalline carbon, although the chemical composition is the same) has many microporous structures whose size is calculated in microns. Just like water can seep into the sand. Formaldehyde, water, and other ingredients can seep into these pores of bamboo charcoal. However, as the experiment shows, there is no special mechanism to restrict the freedom of formaldehyde in bamboo charcoal, except for the fact that they are contained in the pore channels, just as water can evaporate from sand, formaldehyde can also evaporate from bamboo charcoal.
Even the researchers who did the formaldehyde adsorption experiments on bamboo charcoal pointed out that the adsorption of formaldehyde by activated charcoal is not stable, and it is not even as close as the combination with water molecules. If the indoor air humidity is high, the adsorbed water molecules will be more than formaldehyde, and may even squeeze down the formaldehyde previously adsorbed on the bamboo charcoal. Of course, it would be better if some substances that can react with formaldehyde are added to the pores of bamboo charcoal to achieve real elimination of formaldehyde. However, no such product has emerged yet.
Many advertisements intentionally obscure these problems, claiming in general that bamboo charcoal and other activated carbon substances have special “adsorption efficacy”, more often than not, they are taking the meaning out of context and playing sloppy eyes. In actual use, environmental conditions are variable, so there is no way to determine whether bamboo charcoal has adsorbed formaldehyde, and it is not known whether the formaldehyde content in the room has been reduced.
In addition to bamboo charcoal, the use of green plants to deal with formaldehyde is also often heard. That plants to remove formaldehyde is effective?
Plants Vs. formaldehyde: We don’t like formaldehyde, either
The first thing we need to make sure is that formaldehyde is not a good thing for plants either. This chemical also reacts with plant proteins, nucleic acids and lipids, harming plant cells. Plants that are sensitive to formaldehyde gas, such as Trillium (also called foliage flowers in some places), red-flowered edelweiss, and milfoil orchids, can also be injured or even die in a high formaldehyde concentration environment. Red flower edelweiss is particularly sensitive, as long as it is thrown in the formaldehyde concentration of 0.1 mg / cubic meters of the environment, put on 3 hours, there will be 95% of the leaves will be injured (calculated by the area ratio). And, when the formaldehyde concentration increases, the speed of injury is faster, they can only formaldehyde concentration of 0.4 mg / cubic meters in the environment to adhere to 3 hours, and then, the whole leaf becomes yellow-brown and water loss wilted, into a dead grass.
The main reason is that formaldehyde will be combined with the superoxide dismutase in the plant cells, making these key proteins inactive, and then further damage to the cell membrane structure, and finally push down this wall. That’s a critical part of the plant that strictly controls the flow of nutrients, water and waste in and out. At this point, the fate of the plant is naturally conceivable.
Formaldehyde absorption is a defense mechanism for plants
Of course, some plants are more tolerant of formaldehyde, and even have detoxification functions. And then, these plants are worshipped as the magic herb to remove pollution.
In reality, these plants have some “assembly lines” for formaldehyde removal, which react formaldehyde with specific chemicals to produce amino acids (such as serine), or directly into carbonic acid and carbon dioxide, which can be used in the material cycle to make new sugars, fats or proteins. On the surface, this process reduces the damage done to plant cells by formaldehyde and, on the other hand, adds “nutrients” to the plant. After all, there is no difference between the carbon from formaldehyde and the carbon from carbon dioxide. It’s a good way to kill two birds with one stone.
However, it is important to note that this is only a defensive reaction of the plant. To be frank, dealing with formaldehyde is only a last resort activity. Making it harmless and going around in quite a few circles is far less effective than absorbing carbon dioxide.
Absorbing, but not powerful
Since these plants have the ability to absorb formaldehyde, is it reliable to use them to purify formaldehyde in the home?
Researchers measured the ability of some common indoor potted ornamental plants to handle formaldehyde by simulating a room containing formaldehyde. From the absorption efficiency obtained from the experiment, the plants’ ability to handle formaldehyde was not sufficient to significantly reduce the concentration of formaldehyde in the average living room in a short period of time. [2][3] For example, the average rate of formaldehyde treatment by the currently widely respected hanging orchid is 0.15 mg of formaldehyde per hour for a large 1 m2 leaf. [2] In reality, a typical hanging orchid has a leaf area of less than 0.1 square meters. That is, the total amount of formaldehyde that a hanging orchid can process in 1 day is only 0.36 mg. If the concentration of formaldehyde in a 100 square meter, 3 meter high room is 0.5 mg/m3, there is a total of 150 mg of formaldehyde, and at least 120 mg of formaldehyde needs to be removed to get down to the safety standard (0.1 mg/m3)[4]. That’s 333 days of hard work for this hanging orchid. Of course, this does not count the newly evaporated formaldehyde from the decorative materials.
Other plants with the ability to absorb formaldehyde, some with slightly higher absorption rates than the hanging orchid and some with slightly larger foliage areas, would not bring significant improvements, and the actual treatment effect would still be quite limited. In addition, the data of the absorption experiment was obtained in a relatively small space. In other words, formaldehyde cannot yet drift casually in the space, but must always be around the plant to be effectively removed. Figuratively speaking, plants are not vacuum cleaners, but fishing nets for the willing.
Bamboo charcoal and green plants are not good enough, so what can we do? In an experiment about the effect of ventilation on formaldehyde concentration, after 3 months of forced ventilation given to the living room, the concentration of formaldehyde in the room would drop from the initial 0.248 mg/m3 to 0.071 mg/m3, a drop of 75%. [5] It seems that opening windows and ventilation is the most convenient and effective means of removing formaldehyde.
Conclusion: The method is partially feasible, but less effective. The activated carbon substance represented by bamboo charcoal is only adsorption not absorption of formaldehyde, and the unsoundness of this adsorption makes formaldehyde may also be released, and the effect is difficult to guarantee. Although plants such as hanging orchids have a certain ability to absorb formaldehyde, the amount of formaldehyde it absorbs is very limited, and it takes quite a long time to effectively reduce the formaldehyde content in the room. Although there is no harm in these two methods, but do not have too high expectations of their role. On the basis of choosing decorative materials with low formaldehyde content, ensure that the ventilation of the living room is an effective way to reduce formaldehyde pollution. It is better to open the windows more often for ventilation!
Reference.
[1] Yang Lei et al. 2005, Study on the adsorption performance of bamboo charcoal on formaldehyde. Forest Chemistry and Industry, Vol. 25, No. 1
[2] (1, 2) Huang, A. K. et al. 2008, Absorption properties of four indoor potted plants on high concentrations of benzene and formaldehyde. Journal of Environment and Health Year, Vol. 25, No. l2, 1078-0190.
[3] a) Zhou Xiaojing et al. 2006, Effect of 13 commonly used indoor ornamental plants on formaldehyde purification. Chinese Agricultural Bulletin, vol. 22, no. l2, 229-231. b) Cao F., 2008, Research on the purification effect of plants on formaldehyde. Northern Horticulture 2008(6): 150-15. c) Shik Jun-Ning et al, 2010, A study on the use of potted plants to purify formaldehyde released from new indoor flooring. Chinese Agronomy Bulletin, 2010, 26(2): 196-19.
[4] GB/T 18883-2002 (Indoor Air Quality Standard)
[5] Shi, Yanping et al. 2005, Effect of forced ventilation on indoor formaldehyde concentration. Journal of Environment and Health. Vol. 22, No. 6, 472.
Thanks to the original author: Shi Jun