Chemical desiccant can be divided into three kinds of acidic desiccant, alkaline desiccant and neutral desiccant according to their acidity and alkalinity, and the main difference lies in:
1, different uses, acidic desiccant mainly dries acidic or gases such as sulfur dioxide, carbon dioxide, carbon monoxide, nitrogen dioxide and so on; alkaline desiccant mainly dries alkaline or neutral gases such as ammonia, carbon monoxide and so on; Neutral desiccant is used less, generally mainly used for drying neutral gas.
2, desiccant composition is different, acidic desiccant mainly has concentrated sulfuric acid, phosphorus pentoxide, silica gel, etc.; alkaline desiccant mainly has solid caustic soda, lime and soda lime (mixture of sodium hydroxide and calcium oxide), etc.; neutral desiccant mainly has anhydrous calcium chloride, anhydrous magnesium sulfate, etc., but the anhydrous calcium chloride can not be dried ammonia and ethanol.
It should be noted that in the use of desiccant, concentrated sulfuric acid can not dry hydrogen sulfide, hydrogen bromide, hydrogen iodide strong reducing acidic gas; neutral desiccant anhydrous calcium chloride can not dry ammonia and ethanol.
Expanded information:
Desiccant is often divided into two categories: chemical desiccant and physical desiccant. Among them, physical desiccant is dried through physical adsorption of water. It is suitable for preventing instruments, meters, electrical equipments, medicines, food, textiles and other kinds of packaged goods from moisture. Desiccant is also widely used in sea transportation, which can effectively remove moisture and prevent moisture, so that the quality of goods can be guaranteed.
According to the application environment, physical desiccant is generally three kinds of cases:
1. Used in small environment, desiccant is directly placed in bottles, cans or other airtight pouches, so as to make the articles in small environment keep dry.
2. Used in the medium environment, the desiccant is directly placed in the packed carton (or packed drum or bag) to avoid the moisture of the items in the package.
3. Used in large environment, desiccant is directly put in similar warehouse and container to control the purpose of large environment humidity.
Baidu Encyclopedia-Desiccant