Iron-based coagulants are indispensable reagents for water purification due to their ability to function effectively over a broader pH range compared to aluminum-based coagulants. They are primarily used in wastewater treatment across various industries, especially in the food sector.

Iron-based coagulants are mainly differentiated by the chemical nature of their active ingredients, despite having similar concentrations.

Applications of Iron-Based Coagulants:

• Wastewater Treatment:

  • Used in industrial and municipal treatment facilities to remove phosphates, organic substances, and fats.
  • Applied to sludge sedimentation and volume reduction of wastewater.

• Industrial Water Treatment:

  • Utilized in chemical, petroleum, metallurgical, textile, and food industries for purifying process water.

Mechanism of Action of Iron-Based Coagulants:

• Hydrolysis with the Formation of Hydroxo Complexes:

  • Iron-based coagulants, such as FeCl₃ or Fe₂(SO₄)₃, hydrolyze in water, forming hydroxo complexes and colloidal ferric hydroxide, which has high adsorption capacity.

• Charge Neutralization:

  • Similar to aluminum-based coagulants, Fe³⁺ ions or their complexes neutralize the negative charge of colloidal particles, promoting aggregation.

• Coagulation:

  • Ferric hydroxides create “bridges” between contaminant particles, combining them into flocs that easily settle or are removed during filtration.

Advantages of Using Iron-Based Coagulants for Water Treatment:

• Wide pH Range:

  • Iron-based coagulants operate effectively within a pH range of 3 to 11.

• Odor Reduction:

  • By interacting with contaminants, iron-based coagulants efficiently restore the organoleptic properties of water.

• High Reactivity:

  • They facilitate the removal of sulfide ions, phosphate ions, and organic substances.

Alternative Names:

• Ferric chloride (FeCl₃)
• Ferrum(III) chloride
• Ferric sulfate
• Polyferric chloride (PFC)
• Hydrated iron sulfate
• Ferrous sulfate (FeSO₄)
• Liquid ferric chloride