Desiccants are widely used in different fields, such as medicine, health products, diagnostic reagents. Medicinal desiccants require safety, environmental protection, non-toxicity and harmlessness, as well as super hygroscopicity and 100% degradability. Drug desiccants shall obtain the Registration Certificate of Pharmaceutical Packages issued by the State Drug Administration.
What is a desiccant and what is its hygroscopicity principle?
Desiccant is a kind of dehydrating agent which absorbs moisture from the atmosphere. Its drying principle is to absorb water molecules into its own structure by physical means or to change its chemical structure by chemical means to another substance.
What are the main types of desiccants?
At present, there are three typical desiccant products in the desiccant industry:
Silica gel desiccant - The main ingredient is silica, which is refined from natural minerals and becomes granular or beaded. As a slight Tb particle, it has good affinity for water molecules. The most suitable hygroscopic environment for silica gel is room temperature (20-32) and high humidity (60-90%). It can reduce the relative humidity of the environment to about 40%.
Clay desiccant (montmorillonite) - - the appearance of gray pellets, the most suitable for moisture absorption in the environment below 50 C. When the temperature is higher than 50 C, the "drainage" degree of clay is greater than the "water absorption" degree. But clay has the advantage of being cheap.
Molecular sieve desiccant - It is a synthetic desiccant product with strong adsorbability to water molecules. The pore size of molecular sieve can be controlled by different processing technology. Besides adsorbing water gas, it can also adsorb other gases. Water molecules can still be well accommodated at high temperatures above 230 C. Advantages: strong adaptability. Disadvantages: Low moisture absorption rate, poor environmental protection (non-degradable).
How to determine the dosage of desiccant?
The amount of desiccant depends on many factors: the size of drying space, the performance of packaging materials, the storage environment of packaging materials, the atmospheric conditions when sealing, the shelf life of packaging materials, the sealing degree of packaging and so on. When we design the dosage of desiccant for our customers, we need to know the above before we can give the best answer.
What is saturation and what is equilibrium capacity?
Although they are two concepts, for desiccants, in practical sense, they all mean that moisture is no longer absorbed. Saturation means that the desiccant is saturated and cannot be absorbed even if there is more water vapor.
Equilibrium capacity means that the desiccant absorbs enough moisture from the air, so that the air can hold more moisture than the desiccant can absorb water. At this time, adding more desiccants will not reduce the relative humidity of the environment.
What does a unit of desiccant mean?
Desiccant adsorption units commonly used abroad. According to the adsorptive capacity of desiccant: a unit desiccant can adsorb 3.00g water vapor at 25 C equilibrium temperature (RH = 20%) and a unit desiccant can adsorb 6.00g water vapor at 25 C equilibrium temperature (RH = 40%).
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