SREL Reprint #2123

The effect of silica and phosphate on the transformation of schoepite to becquerelite and other uranyl phases

A. G. Sowder1, S. B. Clark2, and R. A. Fjeld1

1Clemson University, Department of Environmental Systems Engineering, Clemson, SC 29634-0919
2University of Georgia, Savannah River Ecology Laboratory, P. O. Drawer E, Aiken, SC 29802

Abstract: The influence of silica and phosphate on schoepite weathering in calcium bearing systems has been examined. The presence of Si (10-3M) retarded the transformation of schoepite to becquerelite in 10-2 and 10-3 M Ca systems as compared to silica free systems. The formation of uranyl silicates was not observed. The presence of phosphate (10-2 M) in a 10-2M Ca system led to the transformation of schoepite into autunite via several intermediate products, including becquerelite and one or more uranyl phosphates. These results indicate the importance of silica and phosphate in the transformation of secondary uranyl phases in natural systems.

SREL Reprint #2123

Sowder, A.G., S.B. Clark, and R.A. Fjeld. 1996. The effect of silica and phosphate on the transformation of schoepite to becquerelite and other uranyl phases. Radiochimica Acta 74:45-49.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).