Novel polyazamacrocyclic receptor impregnated macroporous polymeric resins for highly efficient capture of palladium from nitric acid media

A novel composite resin C-8-Cyclen/CG-71M, with the specific binding ability to palladium ions in HNO3 solution, was developed by impregnating tetraoctyl-substituted 1,4,7,10-tetraazacyclododecane (C-8 -Cyclen) receptor into the macroporous polymeric resins (Amberchrom CG-71M). The structure and morphology of obtained products were fully characterized. Study on the batch experiments revealed that C-8 -Cyclen/CG-71M resin exhibited rapid kinetics, favorable adsorption ability and high selectivity toward Pd(II) in a wide HNO3 concentration. The theoretical interpretation of the experimental data by employing kinetics models, Langmuir/Freundlich isotherms and thermodynamic equations were implemented to describe the adsorption behavior. The results showed that the adsorption process of Pd(II) by C-8 -Cyclen/CG-71M was comforted to a monolayer-coverage with the maximum adsorption capacity of 169.5 mg/g. Besides, the XPS analysis was performed to probe the underlying adsorption mechanism to Pd(II). A suggested mechanism involving the synergistic effect of four cyclic amines in C-8-Cyclen receptors was proposed to describe the interaction manner between Pd(II) and C-8-Cyclen/CG-71M. Furthermore, the resin was also applied to recovery Pd(II) from HCl media and similar results were obtained. Overall, due to the benign synthesis, efficient adsorption ability and facile operation, C-8-Cyclen/CG71M might be a promising resin material for Pd(II) selective capture from radioactive wastes, and other leaching solution of spent catalysts and electronic scraps.