Preparation and graft modification of hierarchically porous ferriferrous oxide for heavy metal ions adsorption

Hierarchically porous ferriferrous oxide (Fe3O4) was facilely synthesized via a sol-gel process accompanied by phase separation, and further graft modified by dopamine (DA) and polyamido-amine (PAMAM) to prepare macroporous Fe3O4@DA@PAMAM for heavy metal ions adsorption. Appropriate phase separation inducer (poly(acrylamide), PAA) and solvent allows the formation of iron oxide xerogels with interconnected macropores and cocontinuous skeletons. Two-step heat treatment at 200 °C for 30 min in air and then at 500 °C for 2 h in N2 atmosphere leads to the precipitation of crystalline phase, Fe3O4, with high magnetic properties, without any deterioration of the macrostructure. The macroporous Fe3O4@DA@PAMAM show a core-shell structure and high adsorption capacity for Cu(II), Pb(II), and Cd(II) ions, which are promisingly used for removal of heavy metal ions.