Abstract
Uranium adsorbed on amidoxime-based polyethylene fibers in simulated seawater can be
quantitatively eluted using 3 M KHCO3 at 40°C. Thermodynamic calculations are in agreement
with the experimental observation that at high bicarbonate concentrations (3 M) uranyl ions
bound to amidoxime molecules are converted to uranyl tris-carbonato complex in the aqueous
solution. The elution process is basically the reverse reaction of the uranium adsorption process
which occurs at a very low bicarbonate concentration (~10-3 M) in seawater. In real seawater
experiments, the bicarbonate elution is followed by a NaOH treatment to remove natural organic
matter adsorbed on the polymer adsorbent. Using the sequential bicarbonate and NaOH elution,
the adsorbent is reusable after rinsing with deionized water and the recycled adsorbent shows no
loss of uranium loading capacity based on real seawater experiments.
