Foam-based and powder-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

A method for forming a foam-based adsorbent for the recovery of metal ions from an aqueous solution, the method comprising:

• exposing a polymer foam to ionizing radiation and co-grafting polymerizable monomers containing nitrile and hydrophilic groups to form grafted side chains;
• reacting the nitrile groups in the grafted side chains with hydroxylamine to convert the nitrile groups into amidoxime groups;
• and
• conditioning the grafted polymer foam with an alkaline solution.

A method for forming a powder-based adsorbent for the recovery of metal ions from an aqueous solution, the method comprising:

• exposing a powder including polymer granules to ionizing radiation;
• co-grafting polymerizable monomers containing nitrile and hydrophilic groups onto the irradiated powder to form grafted side chains;
• reacting the nitrile groups in the grafted side chains with hydroxylamine to convert the nitrile groups into amidoxime groups;
• and
• conditioning the powder with an alkaline solution.