Ferric alum, also known as ammonium iron(III) sulfate, is a double sulfate compound used primarily as a coagulant in water treatment to remove impurities, acting as a flocculant to clump particles for easy removal in drinking water, sewage, and industrial wastewater. It's also vital in the paper industry for sizing and in textiles for fixing dyes, appearing as a light violet to brownish crystal that can dehydrate in dry air.
Key Characteristics
Chemical Formula: NHFe(SO)12HO (Ammonium Iron(III) Sulfate).
Appearance: Light violet to brownish crystalline solid, though small crystals can appear colorless.
Properties: Water-soluble, acidic, and a potent coagulant/flocculant.
Instability: Loses color and transparency quickly in dry air due to dehydration, requiring storage in airtight containers.
Main Uses
Water Treatment: Clarifies drinking water, industrial water, and wastewater by removing suspended solids, color, and turbidity.
Paper Industry: Acts as a sizing agent to improve paper quality, texture, and resistance to ink bleeding.