Selection of the alkylamino group introduced into the polymer chain grafted onto a porous membrane for the impregnation of an acidic extractant

Bis(2-ethylhexyl)phosphate (HDEHP) as an acidic extractant selective for lanthanides was impregnated into an alkylamino group introduced into a polymer chain grafted onto the pore surface of a porous hollow-fiber membrane. The alkyl chain length was varied from 2 to 18 carbons by reacting the glycidyl methacrylate (GMA)-grafted hollow fiber with various alkylamines. The HDEHP-impregnated porous hollow-fiber membrane originating from the GMA-grafted hollow fiber prepared with methanol used as a solvent for GMA had the highest pure water flux among that prepared with methanol, ethanol, 1-propanol, or 1-butanol. The HDEHP impregnated into the dodecyl- or octadecylamino group of the graft chain exhibited the absence of leakage in a high ionic strength medium as well as a high binding ratio of yttrium ion to the impregnated HDEHP. The equilibrium binding capacity of the HDEHP-impregnated porous hollow-fiber membrane for yttrium ion was 0.6 mol/kg of the GMA-grafted hollow-fiber membrane. The HDEHP impregnated into the dodecylamino group was found to efficiently bind yttrium ion in a permeation mode.