What Is Sodium Aluminate?
Sodium aluminate refers to several inorganic compounds that contain sodium and aluminum, including NaAlO2, Na[Al(OH)4], Na2O-Al2O3, and Na2Al2O4. It is soluble in water and insoluble in organic solvents. It is a white solid at room temperature in powder form. Na[Al(OH)4] is typically handled as a liquid due to its difficulty in being isolated as a solid from the solution.
Uses of Sodium Aluminate
Sodium aluminate is widely used in civil engineering, construction, water purification, paper manufacturing, and pharmaceutical manufacturing as a raw material for industrial chemicals. It serves as a hardening agent for soil, an additive for firebricks, a coagulation aid in water treatment, and a sizing agent in paper manufacturing.
Principle of Sodium Aluminate
1. Sodium Aluminate Production Method
Sodium aluminate compounds are synthesized from aluminum (such as solid aluminum, aluminum oxide, or aluminum hydroxide) and strong bases like sodium hydroxide or sodium carbonate. Industrially, aluminum hydroxide Al(OH)3 is dissolved in a sodium hydroxide (NaOH) solution, heated, and dehydrated to obtain NaAlO2.
2. Properties of Sodium Aluminate
Sodium aluminate aqueous solutions are strong bases, reacting violently with acids and corrosive to certain metals. They react with ammonium salts and are considered a fire hazard. Sodium aluminum dioxide (NaAlO2) is water-soluble and forms a strong base when dissolved, easily hydrolyzed to precipitate aluminum hydroxide in weak acids.
Types of Sodium Aluminate
Sodium aluminate products, primarily NaAlO2 and Na[Al(OH)4], are available as chemical reagents and for various industrial applications. They are sold in forms like liquid Na[Al(OH)4] and powder NaAlO2, in packaging such as tank trucks, drums, and paper bags for industrial use.