SELECTIVE AND RAPID UPTAKE OF CU(II) BY BIS(BENZIMIDAZOLE) MODIFIED OXIRANE AND THIIRANE RESINS

The benzimidazole containing ligand 1,3-bis(benzimidazol-2-yl)propylam ine (bbpaH) was anchored onto poly(glycidyl methacrylate-co-trimethylo lpropane trimethacrylate) (GMT) and onto the thiirane analogue of poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) (GME-S). Abb reviations of the modified polymers are GMT-bbpaH and GME-S-bbpaH. A m ultistep synthesis was applied in an attempt to increase the ligand co ncentration on the polymer GMT, This resulted in the resin GMT-bbpaH(i nd) of which the solid state CP MAS C-13-NMR data showed that in this case only a monobenzimidazole was formed, i.e. only the 3-benzimidazol e group was formed. Batch extraction capacities were determined for th e chloride salts of Cu2+, Ni2+, Co2+, Cd2+, Zn2+ and Ca2+ in the pH ra nge 0.9-6.0 in buffered solutions at room temperature. All three resin s show a high selectivity for Cu2+ under competitive conditions, with maximum ligand occupations of 54%, 64% and 27% for GMT-bbpaH, GME-S-bb paH and GMT-bbpaH(ind), respectively. The resin GMT-bbpaH also takes u p some Zn2+ ions at pH > 4.5, the maximum ligand occupation being 17%. The resin GME-S-bbpaH shows some affinity for Zn2+ and Cd2+ ions in t his pH range, with ligand occupations of 17% and 7%, respectively. Onl y GMT-bbpaH(ind) shows complete selectivity for Cu(II) at pH 1 3, alth ough the maximum Cu2+-uptake capacity is rather low. Kinetic experimen ts showed that the oxirane derivative exhibits a faster uptake kinetic s compared with the thiirane analogue. Incomplete stripping of the Cu( II)-loaded ion-exchange resins and loss of Cu(II)-uptake capacity was observed during the regeneration experiments.