A novel NH₂-functionalized nano-sized magnetic polymer adsorbent coupled with tetraethylenepentamine (TEPA), named as TEPA-NMPs, has been obtained via co-polymerization and ring-opening reactions, followed by chemical co-precipitation for the preparation of Fe₃O₄. Three approaches, e.g. by adsorbing Cu(II), Cr(VI) from water simultaneously, or adsorbing Cr(VI) followed by adsorbing Cu(II), and vice versa, were applied for the investigation of adsorption mechanism of TEPA-NMPs in Cu(II), Cr(VI) co-existing water system. The results showed that the adsorption Cu(II) or/and Cr(VI) on TEPA-NMPs was competitive as well as cooperative. The adsorption mechanisms of Cu(II), Cr(VI) co-existing system could be related with coordination interactions, electrostatic attraction, and ion exchange. New adsorbents can be obtained via adsorption of Cu(II) or Cr(VI) by TEPA-NMPs, named as Cu-TEPA-NMPs and Cr-TEPA-NMPs, respectively. Cu-TEPA-NMPs and Cr-TEPA-NMPs can be reused for the adsorption of Cr(VI) or Cu(II), with high selectivity, broad pH applicable range and comparable adsorption properties with TEPA-NMPs itself.

Key words: tetraethylenepentamine-functionalized nano-magnetic ploymers, Cu(II), Cr(VI) co-existing water system, adsorption mechanism, pH effect