Mesoporous silica SBA-15 functionalized with phosphonate derivatives for uranium uptake

Two functionalized SBA-15 materials were prepared by a post-grafting method using phosphonate derivatives of diethylethylphosphonate (DEP) and ethylphosphonic acid (PA), which were used as adsorbents for removal of uranium(VI) from aqueous solution. These materials were characterized by FT-IR, NMR, TEM, nitrogen adsorption/desorption experiments, and elemental analysis. The effect on uranium(VI) sorption behaviors of the functionalized SBA-15 was studied. Typical sorption isotherms (Langmuir and Freundlich) were determined for the sorption process, and the maximum sorption capacity was calculated. The influence of organic functional groups on uranium(VI) sorption was also discussed. As a result, SBA-15-ethylphosphonic acid (SBA-15-PA) possessed not only a good sorption ability and a desirable selectivity for U(VI) over a range of competing metal ions but also an excellent reusability, which has potential application in separation of uranium(VI).