(400a) Adsorption of Uranium From Seawater

Adsorption of Uranium from Seawater

J. Kim, C. Tsouris,
Y. Oyola, R.T. Mayes, C.J. Janke, S. Dai

Oak Ridge National
Laboratory, Oak Ridge Tennessee, 37831-6181, tsourisc@ornl.gov

G. Gill, L.-J. Kuo, J. Wood, K.-Y. Choe

Pacific Northwest
National Laboratory

Polyethylene
fibers functionalized with amidoxime ligands have been tested in laboratory and
field experiments for uranium uptake. Uranium adsorption was scaled up from
5-gallon batch to 110-gallon flow-through columns with recycling prior to continuous
flow-through column tests with seawater. Experimental data were analyzed by
dimensional analysis to provide a better understanding of the rate-limiting step
of the uranium uptake process. Continuous flow-through column experiments have
been performed at the Marine Sciences Laboratory of the Pacific Northwest
National Laboratory, Sequim, WA, the Rosenstiel
School of Marine & Atmospheric Science of the University of Miami, Miami,
FL, and the Woods Hole Oceanographic Institution, Woods Hole, MA. Packed adsorbent
beds have been set up in different configurations to investigate the effects of
flowrate and temperature on uranium uptake kinetics and equilibrium in
flow-through systems. The maximum amount of uranium uptake from seawater tests
was 3.3 mg U/g adsorbent after eight weeks of contact of the adsorbent with
seawater. This amount was three times higher than the maximum adsorption
capacity achieved in this study by a leading adsorbent developed by the Japan
Atomic Energy Agency (JAEA), which was 1.1 mg U/g adsorbent at equilibrium. The
initial uranium uptake rate of the ORNL adsorbent was 2.6 times higher than
that of the JAEA adsorbent under similar conditions. Mathematical analyses have
been performed to provide a better understanding of the uranium uptake behavior
under transient and equilibrium conditions.