Ravi K.P. Gudavalli, Yelena P. Katsenovich
This research evaluated the effect of aqueous hydrogen carbonate solutions on the uranium rate of release from natural Ca-autunite and quantified the process kinetic rate law for a better prediction of the stability of autunite-group minerals. Testing was accomplished via a single-pass flow-through (SPFT) apparatus using buffered aqueous bicarbonate solutions (0.0005 to 0.003 M) at temperatures of 23–90 °C and pH values of 7–11. The release rate of uranium from Ca-autunite was directly correlated to increasing concentrations of hydrogen carbonate solutions and showed strong pH dependency. Ca-autunite kinetic rate law parameters were compared to the values obtained for synthetic Na-autunite. The power law coefficient and intrinsic rate constant were higher at pH 9–11 for Ca-autunite than for Na-autunite. The lower stability of Ca-autunite was attributed to the high Ca-autunite surface cracking, fractures and basal plane cleavages as compared to Na-autunite and the combined effect of the formation of aqueous uranyl–carbonate and calcium uranyl carbonate species as a driving force for uranium(VI) detachment and the formation of secondary Ca–P hydroxyapatite and uranyl phosphate mineral phases as a driving force for phosphate and calcium detachment controlling the net release of elements.
@article{6d02de59-3772-4458-9bee-07120b9c68e0,
title={Comparison of the kinetic rate law parameters for the dissolution of natural and synthetic autunite in the presence of aqueous bicarbonate ions},
author={Ravi K.P. Gudavalli and Yelena P. Katsenovich},
year={2013},
language={en}
}TY - JOUR TI - Comparison of the kinetic rate law parameters for the dissolution of natural and synthetic autunite in the presence of aqueous bicarbonate ions AU - Ravi K.P. Gudavalli AU - Yelena P. Katsenovich PY - 2013 LA - en ER -
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