Diethylenetriamine functionalized silica gel for adsorption of uranium from aqueous solution and seawater

The diethylenetriamine (DETA) organic moiety was anchored covalently on the surface of silica gel to obtain a surface-modified adsorbent abbreviated as Si-DETA. The adsorbent was characterized by FT-IR, Raman spectroscopy, thermogravimetry, scanning electron microscopy, and energy dispersive X-ray analysis. The adsorption behavior of uranium on Si-DETA was studied as a function of pH of the aqueous phase, duration of contact time, and concentration of uranium in the aqueous phase. The kinetics of uranium adsorption on Si-DETA was fitted with pseudo-first order and pseudo-second order kinetic models. The adsorption isotherm obtained from uranium loading was fitted into popular models such as Langmuir, Freundlich, Temkin, and D-R adsorption isotherms. The statistics of fitting revealed that the Langmuir adsorption model obeyed the adsorption data. The performance of the adsorbent was also evaluated under dynamic conditions by passing feed solution containing uranium in a buffered solution and seawater into a fixed bed column containing Si-DETA. The results were compared with those obtained in a batch mode. The study showed the possibility of using Si-DETA for the separation and recovery of uranium from aqueous waste and seawater. (author)