Abstract
A novel method for impregnating extractants to a polymeric porous membrane of hollow-fiber form was suggested to collect metal ions at high rate by permeating a metal-ion-containing solution through the pores of the extractantimpregnated porous membrane. The extractants, such as HDEHP, Cyanex 272, TOPO, and Aliquat 336, were impregnated to the polymer chain grafted onto the pore surface of the porous membrane via a hydrophobic interaction between the hydrophobic moiety contained in the extractant and the long alkyl chain introduced into the graft chain. The amounts of extractants impregnated ranged from 1.2 to 2.1 mole per kg of the GMA-grafted porous membrane, which was comparable to and higher than those of conventional extractant-impregnated beadous resins. For the impregnation of the neutral and basic extractants, the diol and carboxypentylamino groups, respectively, coexisting with hydrophobic groups of the graft chain worked well to retain the permeability after impregnation and to increase the amount of the extractant impregnated. The extractants impregnated to the graft chain were found to bind the metal ions efficiently, i.e., at a molar binding efficiency of 100%. In addition, no deterioration of the amount of metal ions adsorbed after the repeated uses of adsorption and elution procedures revealed that the leakage of the extractants from the graft chain was negligible.
