Immobilization of uranium(VI) onto Mg2Al layered double hydroxide: role of key geochemical parameters

In this study, the sorption of U(VI) from aqueous solution on Mg2Al layered double hydroxide (Mg2Al LDH) was studied as a function of various water quality parameters such as contact time, pH, ionic strength, soil fulvic acid (FA), solid content and temperature by using a batch technique. The sorption of U(VI) on Mg2Al LDH was dependent on pH. The presence of FA increased U(VI) sorption at low pH, whereas decreased U(VI) sorption at high pH. Both kinetics and thermodynamic parameters of the sorption process were evaluated. It was found that the pseudo-second-order model was more suitable for our experiment. The Langmuir model fitted the sorption isotherms of U(VI) better than the Freundlich and D-R model at three different temperatures of 298, 303 and 313 K. The thermodynamic parameters (ΔH°, ΔS°, and ΔG°) were calculated from the temperature dependent sorption isotherms, and the results suggested that U(VI) sorption was a spontaneous and endothermic process. The results demonstrate that Mg2Al LDH is a promising sorbent material for the preconcentration and separation of uranium pollution from large volumes of aqueous solutions.