Desiccants refer to substances that can remove moisture from moist substances. They are usually divided into two categories: chemical desiccants, such as calcium sulfate and calcium chloride, which are dried by combining with water to form hydrates; physical desiccants, such as silica gel and Alumina and the like are dried by physically adsorbing water.
Medicine and health products, biological reagents, food industry-specific desiccant. Special desiccant features: high hygienic requirements, packaging materials passed the US FDA demonstration, the product is small and efficient, delicate and environmentally friendly, has good compatibility and chemical stability.
According to the application environment, there are generally three cases:
(1) Use in a small environment: The desiccant is placed directly in a bottle, can or other closed small bag to keep the items in the small environment dry.
(2) Use in the middle environment: The desiccant is used directly in the packaged carton (or packaging barrel, bag) to prevent the items in the package from getting wet.
(3) Use in the large environment: The desiccant is directly used in similar warehouses and containers to achieve the purpose of controlling the humidity in the large environment.
name | Chemical formula | Water absorption capacity | Drying speed | Acidity | Regeneration method |
Calcium sulfate | CaSO 4 | small | fast | neutral | Drying and regeneration at 163 |
Barium oxide | BaO | - | slow | Alkaline | Cannot reproduce |
Phosphorus pentoxide | P 2 O 5 | Big | fast | Acidic | Cannot reproduce |
Calcium chloride (fused) | CaCl 2 | Big | fast | neutral | 200 drying regeneration |
Magnesium perchlorate | Mg (ClO 4 ) 2 | Big | fast | neutral | Dry regeneration (decomposed at 251 ° C) |
Potassium hydroxide (fused) | KOH | Big | fast | Strong alkaline | Cannot reproduce |
Alumina | Al 2 O 3 | Big | fast | neutral | 110 300 drying and regeneration |
Concentrated sulfuric acid | H 2 SO 4 | Big | fast | Strong acidity | Evaporation and concentration regeneration |
Silica gel | SiO 2 | Big | fast | Acidic | Drying at 120 |
Sodium hydroxide (fused) | NaOH | Big | fast | Strong alkaline | Cannot reproduce |
Calcium Oxide | CaO | - | slow | Alkaline | Cannot reproduce |
Activated anhydrous copper sulfate | CuSO 4 | Big | - | Weakly acidic | 150 drying regeneration |
Magnesium sulfate | MgSO 4 | Big | fast | Weakly acidic | 200 drying regeneration |
Sodium sulfate | Na 2 SO 4 | Big | slow | neutral | Dry regeneration |
Potassium carbonate | K 2 CO 3 | in | slow | Alkaline | 100 drying regeneration |
Sodium metal | Na | - | - | Alkaline | Cannot reproduce |
Note: Be careful when using perchlorate. Carbon, sulfur, phosphorus, and all organic matter must not be in contact with it. Otherwise, a violent explosion will occur, causing danger.
