Polyferric sulfate and ferrous sulfate are similar in name, but they are not the same kind of products. The morphology of PFS is light yellow amorphous powder solid, easily soluble in water, 10% aqueous solution is reddish brown transparent solution, with hygroscopicity. Polyferric sulfate is widely used in the purification of drinking water, industrial water, various industrial wastewater, urban sewage, sludge dewatering and so on.

The molecular formula of ferrous sulfate is FeSO4.7H2O, which is a by-product produced in the process of producing a rare metal product by sulfuric acid method. The appearance of the product is light green or light yellow green crystalline solid. Adding a certain amount can adjust the pH value of alkaline water, organically combine with suspended solids in water, and accelerate precipitation. It is mainly used in water purification and industrial wastewater treatment, and has bactericidal effect at the same time. Ferrous sulfate is also used as food additive, pigment, raw material for electronic industry, hydrogen sulfide deodorant, soil amendment, industrial catalyst, etc.