The preparation of polyferric sulfate (PFS) mainly involves two methods: direct oxidation and catalytic oxidation. Most PFS are prepared using the direct oxidation method, which has a simpler process route and can reduce equipment investment and production steps, thus lowering equipment costs for industrial production. However, this process relies on an oxidant, such as inorganic oxidants like H₂O₂, KClO₃, or HNO₃. The catalytic oxidation method generally uses a catalyst to oxidize PFS using oxygen or air.
This method of producing PFS has advantages such as simple equipment, short production cycle, no catalyst required, impurity-free product, and high stability. However, during the reaction, H₂O₂ decomposes to form O₂ gas, which is released and does not play an oxidizing role in the absence of a catalyst. To reduce O₂ production, the H₂O₂ addition rate needs to be controlled, and the preparation process needs to be intermittent, affecting production efficiency. The relatively high cost of H₂O₂ increases the production cost of PFS, which is detrimental to industrial production.
