Metal uptake by a novel benzimidazole ligand immobilized onto poly(glycidyl methacrylate- co-ethylene glycol dimethacrylate)

Abstract

The novel benzimidazole ligand 4-(2′-benzimidazole)-3-azabutanoic acid has been synthesized and anchored to poly(glycidyl methacrylate- co-ethylene glycol dimethacrylate). The resulting resin contains 1.1 mmol of the ligand per gram of resin. The ligand binding and the resin structure have been confirmed by 13C solid-state cross-polarization and magic-angle-spinning nuclear magnetic resonance spectroscopy, infrared spectroscopy, and elemental analyses. The metal-uptake capacity of the resin for Cu 2+ is 0.7 mmol Cu 2+/g of resin at pH 5. The capacities for Ca 2+, Co 2+, Ni 2+, and Cd 2+ are significantly lower. The uptake of Cu 2+ ions by the resin was found to be rather fast: t 1 2 = 13 min at pH 5.8. The metal uptake from 0.08 M CuCl 2 solutions in concentrated hydrochloric acid (pH −0.8) is still reasonably high: 0.22 mmol/g. Metal-uptake experiments under competitive conditions confirm the high selectivity for Cu 2+. Elemental analyses and spectroscopic data suggest that mainly 1:1 (metal: ligand) complexes are formed on the polymer matrix. Removal of the metal ions from the loaded resins could be effected with 2 M H 2SO 4, although complete removal of Cu 2+ could not be achieved even after 48 h of acid treatment.