Synthesis, characterization and properties of ethylenediamine-functionalized Fe3O4 magnetic polymers for removal of Cr(VI) in wastewater

A series of ethylenediamine (EDA)-functionalized magnetic polymers (EDA-MPs) have been prepared via suspension polymerization with the usage amount of the functional monomer glycidylmethacrylate (GMA) varied during the suspension polymerization procedure. The EDA-MPs were characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), X-ray diffractometer (XRD), thermogravimetry and differential thermogravimetry analysis (TG-DTA), Fourier-transformed infrared spectroscopy (FTIR) and elementary analyzer (EA). The adsorption properties of the EDA-MPs for the removal of Cr(VI) in wastewater were deeply studied. The results showed the adsorption efficiency was highly pH dependent and decreased with the increasing of initial concentration of Cr(VI). The adsorption data taken at the optimized condition, i.e., 35 °C and pH of 2.5 were well fitted with the Langmuir isotherm. The maximum adsorption capacities (qm) of EDA-MPs to Cr(VI) were highly related to the contents of EDA-MPs, i.e., the qm of EDA-MPs to Cr(VI) calculated from the Langmuir isotherm increased from 32.15 to 61.35 mg g−1 with the increasing of the usage amount of GMA. The adsorption kinetic data were modeled by the pseudo-second-order rate equation, and the adsorption of Cr(VI) by all the present EDA-MPs reached equilibrium in 60 min.