Sorption of uranium(VI) on Na-montmorillonite colloids - Effect of humic acid and its migration -

摘要

Sorption kinetics of U(VI) ions and U(VI)-humic acid (HA) complexes on dispersed Na-montmorillonite colloids was investigated at pH 6.0 by kinetic spectra. For the sorption of U ions, we observed the fast and the slow processes. The fast one was considered to be assigned to the sorption on the outer surface of montmorillonite. The slow one was assigned to the sorption in the interlayer. On the other hand, assuming that U-HA complexes were sorbed on montmorillonite by pseudo-fast-order reaction, we observed only the fast process, indicating that U-HA complexes were sorbed on the outer surface of montmorillonite. We studied the migration of U ions and U sorbed on montmorillonite colloids in the absence and in the presence of humic acid through quartz-packed column. It was found that U ions strongly retained in the column, but that more than 60 % of U sorbed on montmorillonite colloids was eluted from the column.