Effect of Sulfate on the Release Rate of Al³⁺ from Gibbsite in Low-Temperature Acidic Waters

Authors

Moira K. Ridley, University of Nebraska-LincolnFollow
David J. Wesolowski, Oak Ridge National Laboratory
Donald A. Palmer, Oak Ridge National Laboratory
Pascale Bénézeth, Oak Ridge National Laboratory
Richard Kettler, University of Nebraska-LincolnFollow

Date of this Version

1997

Comments

Published in Environ. Sci. Technol. 1997, 31, 1922-1925

Abstract

Solubility experiments were performed at 5 °C by reacting 1 g of powdered gibbsite with 45 g of aqueous H₂SO₄-NaCl and HCl-NaCl (0.01 m H+) solutions at 0.1 m ionic strength. The kinetics of dissolution were monitored under extremely undersaturated conditions and appeared to favor a zero-order rate-determining process. The dissolution rate of gibbsite in the sulfate solution was approximately 10 times faster than in the HCl solution, which is consistent with trends reported in the literature for studies performed at higher temperatures. The enhanced dissolution kinetics of gibbsite (and by analogy, other aluminum-containing minerals) in the presence of sulfate may contribute to the elevated Al concentrations observed in natural lowtemperature waters associated with acid rain and acid mine drainage.