Preparation of hydroxy-Fe intercalated bentonite and its adsorption characteristics and mechanism of uranium(VI)

Hydroxyl Fe intercalated bentonite (OH-Fe-Bent) was prepared by Na-bentonite while using hydroxyl Fe as intercalated material. The synthesized OH-Fe-Bent composites applied to adsorb U(VI) from water solution. The effects of pH value, initial U(VI) concentration, temperature and contact time on adsorption of U(VI) for OH-Fe-Bent were experimentally determined, and the process of adsorption was investigated by kinetic and thermodynamic analysis. The corresponding adsorption mechanisms were analyzed by FTIR, SEM, and XRD etc. The experimental results indicate that the maximum adsorption capacity occurs at pH 4 and the removal rate of U(VI) for OH-Fe-Bent reaches 99.55% for initial U(VI) concentration of 10 mg/L and adsorbent dosage of 0.8 g/L at 15℃. Meanwhile the adsorption reaches equilibrium within 90 min. The adsorption process fits well with the Langmuir isotherm adsorption model and pseudo second-order kinetic model (square of correlation coefficient is about 1), and the theoretical saturated adsorption capacity is 97.09 mg/g, adsorption mechanism of U(VI) for OH-Fe-Bent is a monolayer adsorption. The FTIR and SEM analyses show that the structure of OH-Fe-Bent has no change after absorbing U(VI) and the XRD analysis shows that the hydroxyl Fe has already intercalated bentonite.