Removal of Uranium (VI) by Fixed Bed Ion-exchange Column Using Natural Zeolite Coated with Manganese Oxide

The adsorption of uranium (VI) on the manganese oxide coated zeolite (MOCZ) from aqueous solution was investigated in a fixed-bed column. The experiments were conducted to investigate the effects of bed height, flow rate, particle size, initial concentration of uranium (VI), initial pH, presence of salt and competitive ions. The U-uptake by MOCZ increased with initial uranium (VI) concentration and bed height, but decreased as the flow rate and particle size increased. In the presence of salt and competitive ions, the breakthrough time was shorter. The adsorption capacity reached a maximum at pH of 6.3. The Thomas model was applied to the experimental data to determine the characteristic parameters of the column for process design using linear regression. The breakthrough curves calculated from the model were in good agreement with the experimental data. The BDST model was used to study the influence of bed height on the adsorption of uranium (VI). Desorption of uranium (VI) in the MOCZ column was investigated. The column could be used for at least four adsorption-desorption cycles using 0.1 mol.L-1 NaHCO3 solution as the elution. After desorption and regeneration with deionized water, MOCZ could be reused adsorb uranium (VI) at a comparable capacity. Compared to raw zeolite, MOCZ showed better capacity for uranium (VI) removal.