Amidoxime-functionalized materials and their use in extracting metal ions from liquid solutions

A method for extracting metal ions from a liquid solution containing metal ions, the method comprising contacting said liquid solution with a functionalized material useful in absorbing metal ions from aqueous solutions, the functionalized material produced by a method comprising:

• (i) providing a precursor material having nitrile groups appended to its surface, wherein said precursor material is produced by graft co-polymerization of a nitrile-containing vinylic monomer and itaconic acid, thereby producing a precursor material having nitrile groups and carboxylic acid groups derived from itaconic acid on the surface of the precursor material;
• and
• (ii) reacting said nitrile groups with hydroxylamine or a derivative thereof in the presence of a polar aprotic solvent having a boiling point of at least 100° C., at a temperature of 60-80° C. for at least 1 hour, to convert at least a portion of said nitrile groups to amidoxime and imide dioxime groups, followed by reaction with a base to hydrolyze any remaining nitrile groups to carboxylic acid groups;
• wherein said functionalized material has a higher uranium absorption capacity than a functionalized material produced under same conditions except that the nitrile groups are reacted with hydroxylamine or a derivative thereof in only a protic solvent.