Effect of Porogen Type on the Synthesis of Uranium Ion Imprinted Polymer Materials for the Preconcentration/Separation of Traces of Uranium

Abstract.

Ion Imprinted Polymer (IIP) materials were prepared from different porogens by copolymerization of UO₂ ²⁺-5,7,dichloroquinoline-8-ol-4-vinylpyridine ternary complex in the presence of styrene as monomer, divinyl benzene as crosslinking agent and 2,2′-azobisisobutyronitrile as initiator. The uranyl ion was removed on leaching with 50% (v/v) HCl, which leaves cavities in the polymer particles. Of the various porogens tested, 2-methoxy ethanol gave a higher retention/adsorption capacity for uranium and better selectivity for uranium over thorium. The optimum pH value for quantitative enrichment is 5.0–7.0, and desorption can be achieved with 5 mL of 1 M HCl. The retention capacity of the uranyl ion imprinted polymer particles was found to be 34.0 mg g⁻¹ for uranium, which is much higher than blank or ion recognition polymer. More significantly, the selectivity coefficient (S_U/Th) is much higher (∼99.0) with 2-methoxy ethanol as porogen. The polymer particles obtained from this porogen have been characterized by IR, TGA, DTA, XRD, SEM and EDS analysis. Five replicate determinations of 40 µg of uranyl ion present in 1000 mL of aqueous solution with Arsenazo III spectrophotometric method gave a mean absorbance of 0.185 with a relative standard deviation of 2.46%. The detection limit corresponding to 3 times the standard deviation of the blank was found to be 2 ng mL⁻¹.