Sorption and desorption of uranium(VI) on GMZ bentonite: effect of pH, ionic strength, foreign ions and humic substances

The sorption and desorption of uranium(VI) on GMZ bentonite was investigated as functions of contact time, pH, ionic strength, foreign ions, HSs and initial U(VI) using batch experiments. It is revealed that the sorption strongly depended on pH, cations (Li + , Na + and K + ) and anions (CO 3 2− , SO 4 2− and PO 4 3− ). HA benefits the sorption at pH <7.0, while inhibited the sorption at higher pH. Moreover, the hysteresis occurred in the sorption–desorption process in the presence/absence of humic substances. The results could provide data base for the safety assessment of the deep geological disposal repository of high radioactive waste.