A New Type of Amidoxime-Group-Containing Adsorbent for the Recovery of Uranium from Seawater. II. Effect of Grafting of Hydrophilic Monomers

A fibrous adsorbent containing amidoxime groups (AOF) for recovering uranium from seawater was synthesized by the radiation-induced grafting of acrylonitrile (AN) to a fiber followed by the amidoximation of cyano groups of poly(AN) graft chains. When such hydrophilic monomers as N, N-dimethyl-acrylamide (DMAAm) and acrylic acid (AAc) were preliminarily grafted, both the water uptake and the mobility of the sorbed water in AOF were improved in the order: AOF-containing poly-(DMAAm) graft chains (AOF-DMAAm) > AOF-containing poly(AAc) graft chains (AOF-AAc) > AOF without hydrophilic graft chains. The uranium uptake with these adsorbents was, on the other hand, in the order: AOF-AAc > AOF-DMAAm > AOF. The adsorption of alkaline earths was related to the distribution pattern of poly(AAc) graft chains inside the fiber. The adsorbed alkaline earths were eliminated from the adsorbent fiber by introducing a solution of heavy metal ions such as Cu2+.