PREPARATION OF FIBROUS ADSORBENTS CONTAINING AMIDOXIME GROUPS BY RADIATION-INDUCED GRAFTING AND APPLICATION TO URANIUM RECOVERY FROM SEA-WATER

Polypropylene fibers and polyethylene hollow fibers were used as trunk polymers and were irradiated by electron beams with a dose of 200 kGy under N2 atmosphere. Grafting of acrylonitrile to those irradiated fibers was carried out at 40-degrees-C for different periods of time. The degree of grafting was determined as a function of time. The fibrous adsorbents containing amidoxime groups were prepared by the reaction of acrylonitrile-grafted polymers with 3% hydroxylamine in a methanol-water mixture (1 : 1). Distribution of copper ions complexed with amidoxime groups at various adsorption times was obtained by electron-probe X-ray microanalysis. The amidoxime groups are homogeneously distributed in the cross section of fibrous adsorbents. The fibrous adsorbents based upon polypropylene fiber of 40 mum showed a remarkable kinetic behavior for Cu2+. Even after 15 min, the adsorption capacity was 2.32 mmol CU2+ per gram of fiber. Also, the functionalization with hydroxylamine was carried out at different conditions to compare the adsorption characteristics of the resultant adsorbents. Despite having superficially different properties (elemental microanalysis, ion-exchange capacities, adsorption capacity for UO22+), the polypropylene-based fibrous adsorbents showed similar adsorption properties for uranium from sea water. The adsorption tests proved the performance of the polypropylene-based fibrous adsorbents as a promising material for uranium recovery from sea water. In addition, uranium uptake of fibrous adsorbents increased in proportion to the volume of sea water.