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. Highlights: Hierarchically porous Fe₃O₄ was synthesized via a sol-gel accompanied by phase separation, followed by two-step heat treatment. Macroporous Fe₃O₄@DA@PAMAM can be obtained by graft modification of dopamine (DA) and polyamido-amine (PAMAM). Benefiting from the core-shell structure and macrostructure, the Fe₃O₄@DA@PAMAM possesses excellent adsorption capability. [ABSTRACT FROM AUTHOR]