A desiccant is a hygroscopic substance that induces or maintains a dry state (drought) around it; it's the opposite of humectant. A commonly found desiccant package is a solid that absorbs water. Dryers for special purposes may be in a form other than solid, and may work through other principles, such as chemical bonds of water molecules. They are usually found in foods to maintain crispness. Industrially, dryers are widely used to control water levels in the gas stream.
Video Desiccant
Jenis desiccants
Although some desiccants are chemically inert, others are highly reactive and require special handling techniques. The most common drying agents are silica, a white solid that is inert, nontoxic, and insoluble in water. Tens of thousands of tons are produced annually for this purpose. Other common impurities include activated charcoal, calcium sulphate (Drierite), calcium chloride, and molecular sieves (usually, zeolites).
Performance efficiency
One measure of desiccant efficiency is the ratio (or percentage) of water that can be stored in a desiccation relative to the mass of the dryer.
Another measure is the relative residual moisture of air or other liquids that are dried.
The performance of each desiccant varies with temperature and relative humidity and absolute humidity. To some extent, the performance of the desiccant can be precisely described, but most commonly, the ultimate choice best suited to a given situation, how much is used, and in what form, is made based on testing and practical experience.
Color saturation indicator
Sometimes the humidity indicator is included in the desiccant to indicate, by color change, the water saturation level of the dryer. One commonly used indicator is cobalt chloride (CoCl 2 ). Anhydrous cobalt chloride is blue. When bonding with two water molecules, (CoCl 2 o2H 2 O), it turns into purple. Further hydration results in the hexaaquacobalt (II) chloride pink complex [Co (H 2 O) 6 ] Cl 2 .
Maps Desiccant
Apps
One example of dryer use is in the manufacture of insulated windows where zeolites spheroids fill rectangular spacer tubes in the perimeter of glass panels. Desiccant helps prevent condensation of moisture between the panels. Another use of zeolite â € <â € Desiccants induce drought in any environment and reduce the amount of moisture present in the air. Dryers come in many forms and have been widely used in food, pharmaceutical, packing, electronics and many manufacturing industries. Air conditioning systems can be based on desiccants. Desiccants are used in many types of farms to dry newborn animals, such as piglets. Use of good desiccation can help them dry out faster and save energy, which can be very important for animal development. Another use is to reduce bacteria and pathogens that thrive on a wet surface, reducing bacterial stress. However, some desiccants have very high pH levels, which can be harmful to animal skin.
Solvent drying
Desiccants are also used to remove water from solvents, usually required by chemical reactions that do not tolerate water, for example, Grignard reactions. The general method, though not always, involves mixing the solvent with a solid dryer. Studies show that molecular sieves are superior to desiccants relative to chemical drying reagents such as sodium-benzophenone. The filters offer a safe advantage in the air and can be recycled.
See also
- Desiccator
- Humidity buffer
- Humidity indicator card
- Hygroscopy
- Isotherm moisture absorption
- Solar air conditioning
- Oxygen scavenger (oxygen absorber)
- Sorben
- Volatile Corrosion Inhibitor
References
Further reading
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Lavan, Z.; Jean-Baptiste Monnier & amp; Worek, W. M. (1982). "Second Legal Analysis of the Desiccant Cooling System". Journal of Solar Energy Engineering . 104 (3): 229-236. doi: 10.1115/1.3266307. -
S. Sadik; J. W. White (1982). "The real potato seed dries over the rice". Potato Research . 25 (3): 269. doi: 10.1007/BF02357312.
Source of the article : Wikipedia
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