Anion‐Aluminum Hydroxide Gel Interactions

Abstract The interaction of the nitrate, sulfate, and carbonate anion with aluminum hydroxide gel was studied by infrared spectroscopy. A lowering in the anion symmetry due to the interaction with the aluminum hydroxide surface was observed. Evidence suggests that the nitrate anion interaction is outside of the coordination sphere of the aluminum cation and therefore is mainly electrostatic. However, the sulfate and carbonate anions both show evidence of coordination with the surface aluminum cations. The carbonate interaction appears to be the strongest and is believed to be responsible for the relatively high degree of stability of carbonate‐containing aluminum hydroxide gel.