Acceleration effect of sulfate ion on the dissolution of amorphous silica

The dissolution rate of amorphous silica is enhanced by sulfate ions. The zeta potential for silica particles in Na2SO4 solution was lower than that in NaCl solution with the same ionic strength. These facts indicate that the specific adsorption of sulfate ions occurred by overcoming repulsion between negative charges of the SO2−4 ion and SiO− on the surface of silica. The dissolution rate of amorphous silica may be accelerated by the specific adsorption of SO2−4 ions because of a decrease in the strength of the SiOSi bond in amorphous silica due to donation of electron density from the adsorbed SO2−4 ions.

The dissolution of amorphous silica is accelerated by specific adsorption of sulfate ion on the surface of silica. (▴) Pure water. (●) 0.3 M sodium chloride. (■) 0.1 M sodium sulfate.Figure optionsDownload as PowerPoint slide