A nonwoven fabric made of polypropylene coated by polyethylene was used as the trunk polymer in the preparation of a highly efficient new adsorbent. Metal ion uptake capacity has been aimed to be increased by introducing double amidoxime groups per repeating unit of the chains grafted to trunk polymer. The base polymer was irradiated by electron beams with a dose of 200 kGy under N 2 atmosphere and glycidyl methacrylate (GMA) was grafted onto irradiated nonwoven fabric. Grafting conditions were optimized, and GMA-grafted polymer was modified with 3,3 0 -iminodipropionitrile in ethanol at 808C. GMA grafting (150%) was determined to be the optimum degree given that higher extent of grafting rendered the materials brittle. Pendant nitrile groups were then amidoximated by using 6% hydroxylamine in methanol-water mixture (1 : 1). The all-polymeric structures were characterized by using FTIR, SEM, and thermal analysis methods, confirming the grafting, modification, and amidoximation stages gravimetrically, spectroscopically, and visually.

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Particulate and fibrous adsorbents with enriched amidoxime groups were synthesized by using a novel monomer N,NЈ-dipropionitrile acrylamide. The adsorption properties of amidoximated poly(N,NЈ-dipropionitrile acrylamide) [poly(DPAAm)] particles and a nonwoven fabric grafted with the same for UO 2 2ϩ , Pb 2ϩ , Cu 2ϩ, and Co 2ϩ at high concentrations were investigated by batch process. Metal ion adsorption studies were conducted from metal ion solutions with different initial concentrations (100 -1500 ppm). It was shown that particulated amidoximated poly-(DPAAm) has higher adsorption capacity than amidoximated nonwoven fabrics for all metal ions, especially for uranyl ions. The results of the adsorption studies showed that the interaction between UO 2 2ϩ and amidoximated groups agree with the Langmuir-type isotherm. From the Langmuir equation, the adsorption capacities were found as 400 mg UO 2 2ϩ /g dry amidoximated poly(DPAAm) and 250 mg UO 2 2ϩ /g dry amidoximated graft polymer.

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A new type of fibrous adsorbent with excess amidoxime groups was synthesized by radiation-induced graft polymerization. Glycidyl methacrylate (GMA) was first radiation-grafted on polyethylene-coated polypropylene nonwoven fabrics and chemically modified with 3,3 0 -iminodipropionitrile [NH ( -CH 2 -CH 2 -CN) 2 ] (IDPN), which was further reacted with hydroxylamine to obtain graft chains containing two amidoxime groups per graft repeating units. The adsorption properties of this new adsorbent for uranium (U), vanadium (V), lead (Pb), copper (Cu), and cobalt (Co) ions at low concentrations (3.3 -1000 ppb) Vol. 39, No. 7, pp. 1631-1643, 2004 were investigated by a batch process. The adsorbent showed enhanced adsorption capacity for uranium and vanadium ions. In adsorption studies from a mixture of metal ions in aqueous solutions, the adsorbent showed selectivity for metal ions in the following order: V . U ) Cu ! Pb ) Co. The selectivity of the adsorbent was assessed by determining the distribution coefficient D, of the metal ions studied. The U and V ions were shown to be up to six times more selectively adsorbed onto the new adsorbent than the other metal ions.