The main classification of Polyferric Sulfate (PFS) is as follows:

Polymeric Ferric Sulfate (PFS):Polyferric sulfate is commonly classified under the broader category of polymeric ferric salts. These are characterized by their polymeric structure, which distinguishes them from simple iron salts such as ferric chloride or ferric sulfate. Specifically, PFS is synthesized through the polymerization of ferric sulfate and ferric hydroxide, resulting in a complex polymer structure where iron ions are linked together in larger molecules.

Key characteristics of Polyferric Sulfate (PFS) include:

1. Polymeric Structure: PFS molecules are polymeric in nature, containing multiple iron atoms linked together through oxygen atoms. This structure enhances its coagulation and flocculation capabilities compared to monomeric iron salts.

2. High Basicity: PFS exhibits high basicity due to its hydrolyzed iron species, which contributes to its effectiveness in destabilizing particles in water and promoting the formation of dense flocs.

3. Enhanced Performance: The polymeric structure of PFS allows for improved efficiency in water treatment processes, particularly in the removal of suspended solids, organic matter, and color from water. 

4. Application Flexibility: PFS finds applications across various sectors, including municipal water treatment for drinking water purification and industrial wastewater treatment in sectors such as papermaking, textile manufacturing, and food processing.

In summary, Polyferric Sulfate (PFS) is classified as a polymeric ferric salt distinguished by its complex molecular structure and high basicity, making it a preferred choice for water and wastewater treatment applications requiring efficient coagulation and flocculation processes.