Magnetic assisted separation of uranium(VI) from aqueous phase using diethylenetriamine modified high capacity iron oxide adsorbent

Abstract

Processing of uranium ore for the production of reactor-grade uranium results in the generation of large amount of aqueous waste containing small quantities of uranium, but higher than the guideline value (15 μg L−1) recommended by World Health Organization (WHO). The presence of uranium in aqueous waste poses several hazards and environmental issues due to the radioactive nature and migration behavior of uranium in the geosphere. In order to remove uranium (VI) from aqueous waste, the diethylenetriamine modified high capacity magnetic iron oxide adsorbent, abbreviated as Fe-DETA, was prepared and studied for the extraction of uranium from aqueous solutions. The Fe-DETA was characterized by X-ray diffraction, thermal analysis, infrared and Raman spectroscopy, and scanning electron microscopy. Significantly high amount (2 mmol g−1) of diethylenetriamine functional group (DETA) was anchored on magnetic iron oxide particles. The extraction of U(VI) from aqueous phase was studied as a function of pH of the aqueous phase, duration of the contact between Fe-DETA and aqueous phase, concentration of U(VI) in aqueous solution etc. The data on the rate of extraction of U(VI) in Fe-DETA was fitted into the first order and second order rate equations. The apparent uranium extraction capacity on Fe-DETA was determined to be 236 mg g−1, which correspond to the formation of 1:2 complex of U(VI) to diethylenetriamine ligand in Fe-DETA phase. The loaded U(VI) in Fe-DETA was quantitatively recovered using dilute Na2CO3 solution, and the recovered Fe-DETA was recycled for further extraction of U(VI), without any change in the apparent U(VI) extraction capacity.