Comparison of Amidoxime Adsorbents Prepared by Cografting Methacrylic Acid and 2-Hydroxyethyl Methacrylate with Acrylonitrile onto Polyethylene

Abstract

Methacrylic acid (MAA) and 2-hydroxyethyl methacrylate (HEMA) were cografted with acrylonitrile (AN) onto polyethylene fiber by radiation-induced graft polymerization. The cyano groups produced were converted to amidoxime groups (−C( NOH)NH 2 ) by reaction with hydroxylamine (NH 2 OH) to recover uranium in seawater. Various weight ratios of AN/MAA or AN/HEMA in the monomer mixture for cografting generated MAA- and HEMA-cografted amidoxime (AO) fibers with various hydrophilicities. The amidoxime group density and water content were balanced to enhance the uranium adsorption from seawater. MAA-cografted AO fibers exhibited a higher adsorption rate than HEMA-cografted AO fibers. The optimum value of the weight ratio of AN/MAA = 60/40 in the monomer mixture was observed both in a submerged mode at an ocean site and in a flow-through mode in the laboratory. The amount of uranium adsorbed was 0.90 g/kg of the MAA-cografted AO fiber at 293−298 K after 20 days of contact at the ocean site.