SYNOPSISA number of lightly cross-linked poly (acrylonitrile-co-divinylbenzene) beads ( RN-5 ) have been synthesized by suspension polymerization. The use of solvating diluents such as chloroform, dichloroethane, and tetrachloroethane resulted in copolymer beads having highly porous structures. The chelating resins containing amidoxime as a functional group (RNH-5 ) have been prepared by the reaction of copolymer beads with 3% hydroxylamine in methanol. A detailed analysis is made of the pore structure of lightly cross-linked copolymers of acrylonitrile-divinylbenzene and their amidoxime derivatives in the anhydrous state including pore-size distribution, specific surface area, and pore structure in the aqueous media by means of gel permeation chromatography (GPC) . A set of experiments have been performed to ascertain the potential of the resins for the adsorption of uranium from seawater. Because of their modified pore structures, the chelating resins exhibited a marked adsorption rate for uranium in seawater as high as 23 pg of U/cm3 of resinlday without alkaline treatment.

It was found that the chelating resins (RNH) containing amidoxime groups show the selective adsorption ability for uranium in sea water. The favorable chelating resins were prepared by the reaction of macroreticular acryronitrile-divinylbenzene copolymer beads with hydroxylamine in methanol. When sea water (104 times as large as the resin volume) was passed through the RNH column at the space velocity of 60 hr-1, 80% of uranium on that in sea water was recovered. The elution of uranium adsorbed on RNH was accomplished by passing 1 N sulfuric acid solution through it. The recycle of adsorption and elution was found to be satisfactory.

No abstract

SY NOPSlSPolypropylene fibers and polyethylene hollow fibers were used as trunk polymers and were irradiated by electron beams with a dose of 200 kGy under Nz atmosphere. Grafting of acrylonitrile to those irradiated fibers was carried out at 40°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 electronprobe 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 pm 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 UO ;+), the polypropylenebased 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. 0 1993

Lightly crosslinked poly(acry1onitrile-co-divinylbenzene) beads (RN-5) have been synthesized by suspension polymerization. The use of dichloroethane and chloroform as a porogen produced lightly crosslinked copolymer beads having highly porous structures. The chelating resins containing amidoxime groups (RNH-5) have been prepared by the reaction of copolymer beads with NHzOH in MeOH. The resulting chelating resins have been used in the batchwise adsorption of UO:+ from nitrate solutions containing 0.01 m~l . d m -~ UO:+ at pH 3.25. In order to get some measure of the relative performance of each resin in kinetic terms, the extraction of UO:+ was monitored with time and some adsorption profiles were obtained. An increase in porogen content resulted in a marked increase in the batchwise adsorption of UO:+. Alkaline treatment allowed a high swelling and hence rapid accessibility of UO:+ to the ligands. Even after 30 minutes, the alkali-treated resins were 50% loaded.