Influence of hydrolysis on the sorption of metal cations by smectites: Importance of edge coordination reactions |
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| Authors: | John M Zachara James P McKinley |
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| Institution: | (1) Pacific Northwest Laboratory, Geosciences Department, MS: K3-61, PO Box 999, 99352 Richland, WA, USA |
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| Abstract: | A comparison was made between the adsorptive behaviors of Cd2+ and UO
2
2+
relative to two smectites that differed in their ratio of edge sites to fixed-charge sites. Adsorption varied with both pH and ionic strength, consistent with sorptive contributions of ion exchange and coordination reactions to edge hydroxyls. Both clay minerals exhibited a greater affinity for UO
2
2+
than for Cd2+, and the clay with a higher proportion of edge sites retained both ions more strongly. A computational model including fixed-charge sites and edge hydroxyls resulted in a good prediction of overall UO
2
2+
and Cd2+ uptake to both smectites. |
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| Keywords: | Adsorption smectites UO
2
2+ Cd2+ ion exchange surface complexation modeling |
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