Preparation of hydrophilic amidoxime fibers by co grafting acrylonitrile and methacrylic acid from an optimized monomer composition

To improve the adsorption rate of uranium from seawater, hydrophilic amidoxime (Ao) fibers were prepared by co grafting of methacrylic acid (MAA) with acrylonitrile (AN) onto polypropylene fibers and subsequent conversion of the produced cyano group to an amidoxime group by reaction with hydroxylamine. An optimum amidoximation time of 0.75 h was selected at a weight ratio of AN to MAA (x/y) of 80/20. By varying x/y in the monomer mixture, co grafted polymers were prepared. The value of x/y governed the Ao group density and water content of the resultant fibrous adsorbents. As x/y increased, the Ao group density of the fiber increased and its water content decreased. The Ao/MAA adsorbent, based on the Pp fibers prepared by co grafting at an x/y of 60/40 and subsequent amidoximation, exhibited the highest uranium adsorption rate in the flow-through mode.