Desorption of cesium from kaolinite and illite using alkylammonium salts

Abstract This study addresses Cs + desorption from a kaolinite (KGa-1b) and an illite (Morris, IL) by quaternary ammonium ions. The Cs + sorption capacities on the kaolinite and illite were 14 and 24 mmol/kg, respectively. Desorption of Cs + from Cs + -preloaded kaolinite and illite at different loading levels followed different trends. In general, Cs + was more readily removed from kaolinite than from illite. The hydrocarbon chain lengths of the alkylammonium ions had strong influences on Cs + desorption from kaolinite. At the same alkylammonium concentration, the percentage of Cs + removal from kaolinite increased as the chain length of the alkylammonium ions increased because of a stronger affinity for clay surfaces with a longer chain length. In contrast, initial alkylammonium concentrations had a greater influence on Cs + removal from illite than surfactant chain length. As the alkylammonium concentrations increased, the percentage of Cs + desorption increased. For kaolinite, at the same alkylammonium concentration, a higher percentage of Cs + desorption was achieved when Cs + loading was low. As the Cs + loading on kaolinite increased, the percentage of Cs + desorption decreased. In contrast, a higher percentage of Cs + desorption was obtained from illite when Cs + loading was high. The percentage of Cs + desorption decreased as the Cs + loading on illite decreased. For kaolinite and illite with higher Cs + loading, the percentage of Cs + removal increased logarithmically with the increase in the ratio of hexadecyltrimethylammonium/Cs + . A minimum value of 30 for this ratio is required to achieve 80% Cs + removal from kaolinite.