Removal of uranium (VI) ion from aqueous solution by SBA-15

SBA-15, a type of mesoporous material, was employed to remove uranium (VI) from aqueous solution. Variables of the batch experiments were investigated including initial concentration, pH of initial solution, contact time, weight of adsorbent, ionic strength and desorption. The results indicate that the adsorption equilibrium can be reached within 30 min with a saturated adsorption capacity of 203 mg/g at optimum pH of 6 for the fresh calcined SBA-15. According to the coefficients, the isothermal data correlates with the Langmuir model better than the Freundlich model, and the adsorption process follows a pseudo-second order rate equation. Five repeated adsorption–desorption cycles were carried out. The maximum adsorption capacity of SBA-15 in the last four cycles is almost kept at 170 mg/g and achieves equilibrium within 10 min. Therefore, SBA-15 could be as a promising adsorbent to remove uranium ion from aqueous solution with large adsorption capacity, fast adsorption rate and reusability.

► SBA-15 was utilized as an adsorbent for removal of uranium from aqueous solutions.
► The maximum adsorption capacity is 203 mg/g for fresh SBA-15.
► The outer surface of SBA-15 is the main adsorption site.
► Demonstrating an excellent reusability with adsorption capacity of 170 mg/g.