SYNTHESIS, CHARACTERIZATION, METAL-UPTAKE BEHAVIOR OF BIS(BENZIMIDAZOLE) RESIN SUPPORTED ON EPOXIDE POLYMER

The new chelate resins, abbreviated as PNBMZs and PBBMZs based on epoxide polymer, were synthesized by polycondensation of N,N-diglycidyl-4-glycidyloxyaniline or 1,4-bis(2,3-epoxypropyl)benzene with the primary amine group of 1,3-bis(benzimidazol-2yl)propylamine (BBPAH). The ion exchangers contain 2.71–3.23 mmol of the ligand contents per gram of the resin. Batch extraction capacities were determined for the metal chloride salts in buffer solutions in the pH range from -1 to 6.0. The chelate resins were very selective for Cu²⁺, Zn²⁺, Cd²⁺ in the presence of other divalent transition metal ions. The maximum uptake capacities of PNBMZ (synthetic molar ratio = 1:1.5) under non-competitive condition were found to be 0.94 mmol/g for Cu²⁺ at pH = 2, 1.3 mmol/g for Cd²⁺ at pH = 1 and 1.75 mmol/g for Zn²⁺ at pH = -1 respectively. While in the case of PBBMZ, it was 1.39 mmol/g for Cd²⁺ at pH = 1. The metal-uptake behaviors for both of them showed strong pH dependence, and their extraction capacities increase with decreasing pH. The uptake of Cu²⁺ by the resin PNBMZs at pH = 1 was found to be rather fast with t_1/2 = 18 min. Metal-uptake experiments under competitive conditions also confirm that the chelate resins have a high selectivity for Cu²⁺Zn²⁺, Cd²⁺ and the contrary pH dependence.