Aluminum potassium sulfate resembles aluminum sulfate in its properties. It, therefore, serves as a substitute for sodium sulfate in many applications, such as papermaking, dyeing and water purification. Like aluminum sulfate, it has astringent properties. Because of the similarity of the two chemicals, aluminum sulfate is sometimes called alum, even though this name more properly applies to aluminum potassium sulfate.
Sulfur effectively lowers the pH of soil and serves as a substitute for aluminum sulfate in the treatment of excessively alkaline soils. Other chemicals that serve the same purpose are ammonium sulfate and sulfur-coated urea, according to Clemson University.
Aluminum acetate can fulfill some of the same functions as aluminum sulfate. For example, it is an excellent mordant. Like aluminum sulfate, aluminum acetate is an astringent, and enjoys ample use in medicine
In baking, sodium aluminum sulfate enjoys a much wider use than aluminum sulfate. It often serves as an ingredient in baking soda. When applied to pastry in conjunction with sodium bicarbonate, it has a leavening effect.
Ferric sulfate can replace aluminum sulfate as a coagulant in water treatment. Most water destined for home use contains many small particles called colloids that remain in suspension indefinitely. Such coagulants as aluminum sulfate and ferric sulfate cause these colloids to clump together, so that they settle to the bottom. Other coagulants for drinking water impurities are polyaluminum chloride and aluminum chlorohydrate, according to a thesis presented to the University of Waterloo by Walid El Henawy.
To render paper resistant to water, paper makers size their paper. This means that they apply some material, such as gelatin or a starch solution to the surface of the sheet. In the past, manufacturers added aluminum sulfate during the sizing process because it fixed the sizing material to the sheet. Recently, however, synthetic materials, such as polyaluminum silicate sulfate, have been replacing aluminum sulfate. Polyaluminum silicate sulfate has also been used in the water purification process. "Polyaluminum" stands for polymeric aluminum.