Selective extraction of uranyl ions using ion-imprinted chelating microspheres

• Uranyl complex with Schiff base derived from p-aminostyrene and salicyaldehyde (HASS).
• The prepared [UO2(ASS)2] complex were copolymerized with styrene and divinylbenzene.
• The uranyl ions were removed from the cross-linked network to produce the uranyl ion-imprinted resin.
• The resin was applied to selectively remove UO22+ ions from aqueous solutions.

In this work, uranyl complex with Schiff base derived from condensation of p-aminostyrene and salicyaldehyde (HASS) was synthesized. Both ligand and uranyl complex were characterized using elemental analysis, FTIR, 1H and 13C NMR spectra. The complex was then copolymerized with styrene and divinylbenzene cross-linker using potassium persulfate free radical initiator through emulsion polymerization technique. The uranyl ions were then leached out from the cross-linked network to finally produce uranyl ion-imprinted microspheres (U-PASS), which were investigated using SEM and FTIR. The effect of various significant parameters such as pH, temperature, contact times and initial uranyl concentration on the removal of uranyl from aqueous solution was examined and the results indicated that the adsorption was exothermic in nature and the kinetics of adsorption fit with the second-order kinetic model. Also, Langmuir adsorption isotherm exhibited the best fit with the experimental results with maximum adsorption capacity 147.8 mg/g. Moreover, the selectivity studies revealed that the ion-imprinted microspheres resin exhibited an obvious affinity toward the uranyl ions in presence of other interfering metal ions compared to the non-imprinted resin.

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