2017 Volume 66 Issue 11 Pages 771-782
Polymeric adsorbents capable of capturing and purifying rare metal ions were prepared using radiation-induced graft polymerization. Polymeric chain was appended onto porous polyethylene membrane or sheet, and nylon-6 fiber, followed by the introduction of chelate-forming groups and the impregnation of extractants. First, adenine, one of four nucleic acids, was immobilized to the polymer chains grafted onto porous polyethylene hollow-fiber membrane or 6-nylon fiber to specifically bind palladium or ruthenium ionic species. The density of adenine immobilized was 0.85 mmol g−1, which was comparable to the ion-exchange group density of conventional ion-exchange beads. HDEHP, bis(2-ethylhexyl) phosphate, representative of acidic extractants was impregnated onto the polymer chains grafted onto porous polyethylene sheet or 6-nylon fiber. During the permeation of yttrium solution through the HDEHP-impregnated porous sheet with a density of HDEHP impregnated of 3.4 mmol g−1, the amount of yttrium ions adsorbed was constant irrespective of flow rate because of negligible diffusional mass-transfer resistance in the pores. Neodymium and dysprosium ions loaded onto the HDEHP-impregnated fiber-packed bed were purified by elution chromatography at a high loading and a high flow rate, compared with HDEHP-impregnated bead-packed bed. Neodymium and dysprosium ions loaded onto the HDEHP-impregnated fiber-packed bed were purified by elution chromatography at high loading and high flow rate, compared with HDEHP-impregnated bead-packed bed. Third, hybrid fibers coexisting of dodecane-thiol group with dioctyl sulfide specifically collected palladium ions in concentrated HCl medium.