The selection of an appropriate coagulant is a critical decision in water and wastewater treatment. Among iron-based coagulants, both Ferric Sulfate and Polyferric Sulfate (PFS) are widely recognized. However, they possess distinct differences in their chemical structure, properties, and ultimately, their performance. For procurement managers and engineers, understanding these nuances is vital to selecting the most effective and economical solution. This comparison aims to clarify the distinctions, drawing on insights from leading chemical suppliers. As a prominent polyferric sulfate manufacturer in China, we are well-positioned to explain these differences.

Chemical Structure and Nature:

The primary difference lies in their molecular architecture. Ferric Sulfate (Fe2(SO4)3) is a simple inorganic salt, a low-molecular-weight compound. In contrast, Polyferric Sulfate (CAS No. 10028-22-5) is an inorganic polymer. Its structure, [Fe2(OH)n(SO4)3-n/2]m, features multiple iron ions linked by hydroxyl and sulfate groups, forming long, chain-like molecules. This polymeric nature gives PFS its superior characteristics.

Physicochemical Properties:

These structural differences translate into significant variations in their properties:

  • Molecular Weight and Charge Density: PFS, being a polymer, has a much higher molecular weight and a greater number of positively charged iron species per unit mass compared to Ferric Sulfate. This higher charge density allows PFS to neutralize colloidal charges more effectively and form stronger, larger flocs.
  • Coagulation Efficiency: Due to its enhanced charge density and bridging capabilities, PFS generally exhibits superior coagulation and flocculation performance. It requires lower dosages to achieve similar or better results than Ferric Sulfate, especially in complex wastewater matrices.
  • pH Influence: While both are acidic, the polymerized structure of PFS tends to cause less drastic pH shifts in treated water compared to Ferric Sulfate, potentially simplifying pH control requirements.
  • Corrosivity: Ferric Sulfate can be more corrosive due to the higher concentration of free trivalent iron ions. PFS, with its polymerized form, is generally less corrosive.
  • Appearance: Ferric Sulfate is typically a grayish-white to yellowish powder. PFS is commonly a yellow to reddish-brown amorphous powder or granular solid.

Applications and Usage:

Both compounds can be used in water treatment, but their primary applications differ:

  • Ferric Sulfate: While it can be used in water treatment, its applications are more frequently found in medicine, industrial fertilizers, and as an analytical reagent or catalyst.
  • Polyferric Sulfate: PFS is primarily engineered for water and wastewater treatment. It is highly effective in removing turbidity, color, organic matter, heavy metals, and in improving sludge properties. Its superior performance makes it the preferred choice for challenging industrial and municipal effluents.

When considering your water treatment needs, choosing between these two iron salts depends on the specific requirements of your process. If you are looking for a more effective, efficient, and potentially less corrosive coagulant for water purification, and are seeking to buy polyferric sulfate powder, then PFS is likely the superior choice. As a dedicated supplier of polyferric sulfate, we offer high-quality PFS at competitive polyferric sulfate price points. We encourage you to consult with our experts to determine the best solution for your facility.