Adsorption behavior of metal ions on alkylhistidine extractant impregnated resins: Effect of functional groups of histidine

Two types of alkylhistidine extractants, histidine-2-ethylhexyl amide (His-EH) and N-p-tert-octylphenoxyacetyl-histidine (OP-His) were prepared. The alkylhistidine extractants were impregnated onto a methacrylate-based polymer support to investigate the adsorption selectivity for metal ions. His-EH, which has coordinating imidazole and amino groups, adsorbs Cu(II), Ni(II), Zn(II) and Co(II) at pH > 5. By contrast, OP-His, which has imidazole and carboxyl groups, shows adsorption selectivity; Cu(II) > Zn(II) > Ni(II) > Co(II). A column was packed with OP-His impregnated resin to investigate the separation selectivity between Cu(II) and Co(II). Cu(II) was selectively adsorbed and was efficiently concentrated to 59 times the concentration of the feed solution.