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Several common desiccants in life

Desiccant is a dehumidification material, which plays a drying role by adsorbing or absorbing moisture in the air.

The application history of desiccant is not short. As early as 1773, it was found that charcoal had the function of drying and adsorption.

With the development of desiccant, according to the existing state, desiccant can be divided into three categories: solid desiccant, liquid desiccant and composite desiccant. Generally speaking: solid desiccants include silica gel, zeolite, activated carbon, molecular sieve, activated alumina, anhydrous calcium chloride, calcium oxide (also known as quicklime), etc;

Liquid desiccant includes calcium chloride solution, lithium chloride solution, lithium bromide solution, concentrated sulfuric acid, etc;

The composite desiccant is porous material halogen salt composite material, etc.

At present, desiccant is the most widely used and deeply studied in the refrigeration industry. However, because this kind of desiccant is generally in the interior of refrigeration machines such as air conditioners, it is difficult for people to contact it directly.

What are the common desiccants in life?

Food, cosmetics, drugs and other daily necessities are large users of desiccants, because we should prevent items from becoming damp and moldy.

Generally, the desiccant in this kind of daily necessities has special packaging, which can be filter paper, non-woven fabric, composite paper, etc. It will be printed with warning words such as "inedible", which translates as "do not eat or put in the microwave"; Some will also indicate the specific ingredients.

Common desiccant components in daily life include:

① Quicklime, called calcium oxide, is usually formed by calcination of limestone (mainly calcium carbonate). Young and middle-aged netizens with rural life experience may have seen the scene of lime burning in a lime factory.

In modern life, people rarely see quicklime. Maybe someone will ask: isn't the white slurry painted by gardeners on the tree trunk? In fact, before adding water, it was quicklime, but after adding water, it became mature lime, that is, the white slurry applied to the tree is hydrated lime.

Quicklime is often used as desiccant because of its good hygroscopic effect, convenient source and low price. Most of the desiccants in small foods are made of quicklime.

② Calcium chloride is only one word different from the above-mentioned "calcium oxide", but it is two completely different substances.

Calcium chloride is a kind of halogen salt. Industrial calcium chloride is generally obtained from sea salt by ammonia alkali method. In fact, calcium chloride is not far from people's life, especially for northern residents, because the thing used to remove snow and ice in winter is industrial calcium chloride.

In addition to calcium chloride for industrial use, there are calcium chloride for food and medicine.

Food and medicine grade calcium chloride is produced from low concentration hydrochloric acid and limestone. This grade of calcium chloride is generally used as stabilizer, thickener, desiccant and taste improver in food. Calcium chloride can also be made into calcium chloride injection for the treatment of calcium deficiency and magnesium poisoning.

③ Silica gel is a highly active adsorption material, which is usually prepared by the reaction of sodium silicate and sulfuric acid, and then through a series of post-treatment processes such as aging and acid bubble [5].

For the use of silica gel, everyone must know its application in plastic and cosmetic surgery. In fact, it is also widely used as a desiccant because of its good safety. For example, silica gel desiccant can be often seen in some cosmetics, electronic products and clothing, as well as in more expensive food.

④ Tea bag desiccant is also very common. It is packed in small bags of non-woven fabric or filter paper. The specific composition is unknown, but it is generally described as broken tea.

Because the broken tea powder is a hollow and fluffy structure with large surface area, it has certain hygroscopicity, but the hygroscopicity is not strong, and its main function is to remove the taste.

This is the desiccant I drink. As for what it tastes like, it does smell like tea. You should never drink in water because you are curious about its taste!

⑤ Gray powder or light red block: montmorillonite desiccant. Montmorillonite itself is also a clinically used antidiarrheal drug. Children's misuse will not cause obvious harm. Please drink plenty of water to promote discharge.

⑥ Gray round particles: mineral desiccant. The shape of this desiccant is gray, cyan or yellow round particles, which looks a bit like cat litter. Generally, the mineral desiccant may be large. Because the appearance is not attractive, it is usually not eaten by children.

Mineral desiccant generally takes natural attapulgite clay as the main raw material, a natural magnesium aluminosilicate containing water. Due to the adsorption of this material, the corresponding drugs with attapulgite clay as the main component have been available for a long time. It is mainly used for mucosal protection and treatment of diarrhea. Its clinical effect is similar to montmorillonite. After being taken by mistake, it has no obvious impact on the human body and does not need special treatment.

⑦ Brown powder: ferric oxide, which is mostly used as deoxidizer in food. Deoxidizer is generally written on the package, and the dehydration performance is not very strong. The taste is very poor. Even if children take it by mistake, there will not be many, so there is no need for special treatment.

If you eat more by mistake and have symptoms of nausea, vomiting, abdominal pain and diarrhea, you must give gastric lavage.