Desorption of cesium from kaolinite and illite using alkylammonium salts: Fid-Bau Portal

Desorption of cesium from kaolinite and illite using alkylammonium salts

Willms, Cari / Li, Zhaohui / Allen, Lori / Evans, Christine V

AbstractThis 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.