Interaction of uranium from seepage water with hydroxyapatite.

Column experiments used synthetic rock-pile seepage water, based on samples from Schlema uranium mine in Germany, percolating through packed quartz sand to quantify and characterise U(VI) retardation by hydroxyapatite. Batch experiments were also of assistance in assessing hydroxyapatite as a potential component for reactive barriers. The sorption of uranyl ions on phophate groups was found to be as important as their sorption on silanol groups, outweighing the low phosphate content. In the column experiments, retardation factors of around 30 were observed. The results suggested that the elution of U is governed by two processes of different rate, a conclusion consistent with the findings of time-resolved laser-induced fluorescence spectroscopy.
Column experiments used synthetic rock-pile seepage water, based on samples from Schlema uranium mine in Germany, percolating through packed quartz sand to quantify and characterise U(VI) retardation by hydroxyapatite. Batch experiments were also of assistance in assessing hydroxyapatite as a potential component for reactive barriers. The sorption of uranyl ions on phophate groups was found to be as important as their sorption on silanol groups, outweighing the low phosphate content. In the column experiments, retardation factors of around 30 were observed. The results suggested that the elution of U is governed by two processes of different rate, a conclusion consistent with the findings of time-resolved laser-induced fluorescence spectroscopy.