Batch sorption experiments and time-resolved laser-induced fluorescence spectroscopy (TRLFS) technique were applied to investigate uranium(VI) sorption and desorption on phlogopite in the presence of humic acid (HA). The results showed that HA inhibited U(VI) sorption on phlogopite above pH 4 and such effect became much more pronounced by increasing HA concentration from 20 mg/L to 50 mg/L.  Below pH 4, the presence of HA made little difference on U(VI) sorption.  Thus the cause of the inhibition effect was likely due to the formation of soluble U(VI)-HA binary complexes.  Time-resolved U(VI) fluorescence spectra clearly indicated formation of multiple U(VI) surface complexes, including ternary U(VI)-HA-phlogopite species. Results of U(VI) desorption experiments showed that U(VI) sorption in the presence of HA was  reversible while introduction of HA after U(VI) sorption completion did not cause U(VI) desorption from phlogopite within 48 hr, providing further evidence that U(VI) sorption involved U(VI)- HA-phlogopite ternary complex (SO-OOC-HA-U(VI)).

Retardation and release study of uranium(VI) on phlogopite at the presence of HA: Batch and TRLFS study

248th National Meeting (2014)

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