Preparation method of PFS

Preparation method of polymeric ferric sulfate

The preparation of polymeric ferric sulfate mainly includes direct oxidation method and catalytic oxidation method. Most PFS are prepared using direct oxidation method, which has a relatively simple process route and can reduce equipment investment and production links in industrial production, lowering equipment costs. However, this production process must rely on inorganic oxidants such as H2O2, KClO3, HNO3, etc. Catalytic oxidation method generally uses a catalyst to prepare polymeric ferric sulfate by oxidation with oxygen or air.

The following is the specific operation method for preparing polymeric ferric sulfate:
Hydrogen peroxide oxidation method:
Hydrogen peroxide (H2O2) is a strong oxidant in acidic environments, which can oxidize ferrous to trivalent iron to produce polymeric ferric sulfate
2FeSO4 + H2O2+ (1-n/2)H2SO4—→Fe2(OH)n(SO4)3-n/2+ (2-n)H2O
During the preparation process, ferrous sulfate, water, and sulfuric acid are added to the reaction kettle according to the production volume and required basicity. When the temperature rises to 30-45 ℃, H2O2 is slowly added to the bottom of the kettle through the feeding tube during the stirring process. H2O2 quickly oxidizes ferrous to trivalent iron. When the concentration of ferrous drops to the specified concentration, the reaction is stopped.
The production of polymeric ferric sulfate using this method has the characteristics of simple equipment, short production cycle, no need for catalysts in the reaction, no impurities in the product, and high stability. However, during the reaction process, H2O2 decomposes to form O2 gas, which does not have an oxidizing effect in the absence of a catalyst. To reduce the production of O2, it is necessary to control the rate of H2O2 input and prepare the process in an intermittent manner, which affects production efficiency. The cost of H2O2 is relatively high, which increases the production cost of polymeric ferric sulfate and is not conducive to industrial production. B