Chelation of Iron and Nickel Metal Ions From Aqueous Solutions Using Poly(aminoamide) Dendrimers

In this study, removal of different Fe and Ni metal ion concentrations from contaminated water was achieved by using fourth generation poly-aminoamide (PAMAM) dendrimer with terminal hydroxyl groups (G4-OH) in aqueous solution. Dendrimers are well defined and highly branched polymers with controllable architecture that consist of a core, interior and terminal branch units, and they can be used as a nanoscale container for toxic metals ions in aqueous solution. The chelation process between Fe⁽⁺³⁾ and Ni⁽²⁺⁾ metals ions and the internal tertiary amine groups of the dendrimers was monitored visually and recorded using digital imaging. To quantify the results, time resolved UV-Vis absorption spectroscopy was used. Transmission Electron Microscopy and X-ray absorption spectroscopy were used to measure the size and distribution of the zerovalent metals after reduction of the coordinated metal ions to investigate the dispersion of the metal ions uptake by the usage of dendrimer. The results indicates the formation of mostly monodisperse metal clusters with diameter in the range of 1 to 2nm (40-400 atoms/cluster), which is consistent with the mole equivalent of the original metal ion to dendrimer concentration.