Used primarily in water treatment to remove impurities through coagulation and flocculation. It helps clarify drinking water and treat wastewater by binding with suspended particles and settling them out. Also applied in paper manufacturing as a sizing agent to improve ink absorption and strength. Commonly used in soil pH adjustment for agriculture, especially to increase acidity for plants like blueberries. Found in fire retardants, antiperspirants, and textile processing for dye fixation.