Sodium dihydrogen phosphate (NaH2PO4) is an important chemical, widely used in food, medicine, printing and dyeing, metallurgy and other fields. In the field of raw materials for chemical production, there are mainly the following manufacturing methods for disodium phosphate:
1. Wet phosphoric acid method preparation
Wet phosphoric acid method preparation of disodium phosphate is to use phosphate ore, sulfuric acid and soda ash as raw materials, after the reaction to obtain disodium phosphate. The specific steps are as follows:
(1) Crush phosphate rock to a certain size, and react with sulfuric acid to generate phosphoric acid.
(2) Add soda ash into phosphoric acid, and react to produce sodium dihydrogen phosphate and sodium sulfate.
(3) Filtering, crystallization, centrifugal separation, drying, to get the product of sodium dihydrogen phosphate.
This method has the advantages of easy availability of raw materials and simple process, but the production process produces a large amount of waste residue and waste gas, which causes some pollution to the environment.
2. Preparation by trisodium phosphate method
The preparation of disodium phosphate by trisodium phosphate method is to use trisodium phosphate and sulfuric acid as raw materials, and obtain disodium phosphate after reaction. The specific steps are as follows:
(1) Add trisodium phosphate to sulfuric acid, and react to produce sodium dihydrogen phosphate and sodium sulfate.
(2) Filtering, crystallization, centrifugal separation, drying, to get the product of sodium dihydrogen phosphate.
This method has the advantages of higher yield and better product quality, but the production process needs to use a large amount of sulfuric acid, and the cost is high.
3. Ion exchange method preparation
Ion exchange method preparation of disodium phosphate is to use ion exchange resin and phosphoric acid as raw materials, and get disodium phosphate through ion exchange reaction. The specific steps are as follows:
(1) Pass the phosphoric acid through the ion exchange resin, and the sodium ions in the resin are exchanged with the hydrogen ions in the phosphoric acid to produce disodium phosphate and sodium hydroxide.
(2) Crystallize, centrifugally separate and dry the generated sodium dihydrogen phosphate solution to obtain a sodium dihydrogen phosphate product.
This method has the advantages of high product purity and easy operation, but the resin needs to be regenerated periodically and the cost is high.
In summary, the above three methods can be used to prepare disodium phosphate, but each has its own advantages and disadvantages. In the actual production, the suitable preparation method should be selected according to the specific situation. At the same time, in order to reduce production costs and improve product quality, it is also necessary to continuously optimize the production process and equipment, improve the degree of production automation, strengthen the environmental protection management in the production process, and promote the sustainable development of the manufacturing industry of sodium dihydrogen phosphate.
