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What is a desiccant, and what is its hygroscopic principle?

Date of issue:2018-09-19 14:35
Desiccant is a dehydrating agent that absorbs moisture from the atmosphere. Its drying principle is to absorb water molecules by physical means in its own structure or by chemical means to absorb water molecules and change its chemical structure into another substance.
What are the main types of desiccant?
Desiccant a lot of types, desiccant industry at present there are three typical desiccant products: silica gel, clay (that is, montmorillonite) and molecular sieve.
(1) silica desiccant - the main component is silica dioxide, from the natural mineral after purification and processing into granular or bead. As a desiccanter, its microporous structure (average of 2A). Has a good affinity for water molecules. The most suitable hygroscopic environment for silica gel is room temperature (20~32), high humidity (60~90%), which can reduce the relative humidity of the environment to about 40%.
(2) mineral desiccant - the appearance of the shape of gray balls, the most suitable for moisture absorption in the environment below 50℃. When the temperature is higher than 50℃, the clay will release more water than it absorbs. But clay has the advantage of being cheap.
(3) molecular sieve desiccant - it is a synthetic desiccant with strong adsorption to water molecules. The size of the molecular sieve pore size can be controlled by different processing technology, in addition to adsorption of water gas, it can also adsorption other gases. At high temperatures above 230 ° c, it can still contain water molecules well. Advantages: adaptable. Disadvantages: low moisture absorption rate, poor environmental protection (non-degradable).

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