Adsorption of uranium by diethylenetriamine functionalized magnetic mesoporous silica

The iron oxide (Fe₃O₄) embedded mesoporous silica was prepared and functionalized with diethylenetriamine (DETA) functional groups for the separation of uranium from aqueous medium. The prepared product was abbreviated as Fe-MCM-DETA. The Fe-MCM-DETA was characterized by Raman spectroscopy, particle size distribution, X-ray diffraction, BET surface area, BJH pore size distribution, thermogravimetry, FT-IR, scanning electron microscopy, and transmission electron microscopy. The adsorption of uranium on Fe-MCM-DETA was evaluated as a function of various aqueous phase parameters such as pH, duration of equilibration, concentration of uranium in the aqueous phase, and presence of interfering ions. The adsorption of uranium on Fe-MCM-DETA followed the second-order rate equation. The maximum adsorption capacity of uranium was determined to be ∼470 mg.g⁻¹ at pH 6 by Langmuir adsorption isotherm modeling. The results obtained from adsorption studies and the physical properties of Fe-MCM-DETA were compared with DETA functionalized on Fe₃O₄ (Fe-DETA), silica gel (Si-DETA), and mesoporous silica (MCM-DETA). The uranium loaded on Fe-MCM-DETA was retrieved using Na₂CO₃ solution, the feasibility for recycling of Fe-MCM-DETA without much loss of adsorption capacity was studied, and the results are reported in this paper.