High-performance collection of palladium ions in acidic media using nucleic-acid-base-immobilized porous hollow-fiber membranes

We prepared nucleic-acid-base-immobilized porous membranes of a hollow-fiber form with pore size, porosity, and thickness of 0.2 μm, 70%, and approximately 0.7 mm, respectively. Glycidyl methacrylate was graft-polymerized onto a polyethylene-made porous hollow-fiber membrane, followed by ring-opening of the epoxy group with the amino groups of adenine, guanine, and cytosine. The collection of palladium ions was achievable during the permeation of palladium chloride solution through the adenine-immobilized porous hollow-fiber membrane. The diffusional mass-transfer resistance of palladium ion to immobilized adenine was negligible because palladium ion was transported by permeative flow through the pores. The adenine-immobilized porous membrane with an immobilization density of 0.85 mol/kg of the membrane exhibited the highest molar binding ratio of palladium ion to immobilized adenine of 0.31 in 1 M hydrochloric acid. In addition, a quantitative elution with 4 M hydrochloric acid was experimentally demonstrated.