Aluminium sulfate

Aluminium sulfate is an inorganic salt composed of aluminium cations and sulfate anions. It is used chiefly as a coagulant in water treatment and in papermaking and dyeing.

Coagulation: A process in which fine suspended particles aggregate into larger clusters that can be separated. Aluminium sulfate promotes particle aggregation during water treatment.
Drinking water treatment: Treatment processes that make source water safe and acceptable for consumption. Aluminium sulfate is a common coagulant in conventional drinking-water treatment.
Aluminium: A lightweight metallic chemical element with symbol Al and atomic number 13. Aluminium provides the cations in aluminium sulfate.
Ferric chloride: An iron(III) chloride salt used as a coagulant and in several chemical processes. It is an alternative coagulant with different performance and residual-ion tradeoffs.
Flocculation: The gathering of destabilized particles into larger, removable flocs. After aluminium sulfate destabilizes particles, mixing helps them form settling flocs.
Papermaking: The manufacture of paper from pulp by forming and drying a fiber mat. Aluminium sulfate has historically helped control sizing and retention in papermaking.
Sulfate: The polyatomic anion SO₄²⁻, consisting of one sulfur atom bonded to four oxygen atoms. Sulfate is the counterion paired with aluminium in the salt.
Polyaluminium chloride: A family of pre-hydrolyzed aluminium coagulants used in water and wastewater treatment. It can achieve coagulation with different pH effects and dosing requirements.
Aluminium hydroxide: An aluminium compound that is sparingly soluble in water and forms gelatinous precipitates. Water treatment with aluminium sulfate commonly produces this precipitate, which traps suspended matter.
Sizing: Treatment of paper or textiles to control absorbency, strength, or surface properties. Aluminium sulfate was used with rosin sizing to make paper resist water penetration.

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