Anion effects on the retention of selected actinides on geologic media
Date Issued
March 1, 1980
Author(s)
Krajewski, Thesia Mary
Advisor(s)
Joseph R. Peterson
Additional Advisor(s)
James Q. Chambers
G. Davis I'Kelley
Abstract
The distribution coefficients of americium-241 and neptunium-235 were measured on several minerals in synthetic groundwater and NaCl solutions. The minerals studied contain complexing anions within their crystalline lattices, and they were characterized for purity, ion exchange capacity, and surface area. A batch equilibration technique was used to determine the uptake of americium-24l and neptunium-235 by the minerals over a pH range of 4.0 to 9.0. It was found that apatite [Ca5(PO4)3(F,OH,Cl)], dolomite [CaMg(CO3)2], marble (CaCO3), fluorite (CaF2), and to a lesser extent anhydrite (CaSO4) sorbed americium-241 more strongly than did the other minerals. The distribution coefficients obtained on these minerals were higher in value and less pH dependent than the distribution coefficients obtained on the majority of minerals. Apatite was found to be the only mineral to sorb neptunium-235 very strongly. Precipitation and ion exchange reactions were found not to be important sorption mechanisms. Anionic complexation, especially with OH- and CO2-⁄3, and and/or chemisorption were reasoned to be playing an important role in the sorption of americium-24l and neptunium-235 on apatite, dolomite, marble, fluorite, and anhydrite. The significance of these results iies in isolation of nuclear wastes.
Degree
Master of Science
Major
Chemistry
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