Adsorptive removal of sulfonamides from water by magnetic nanocomposite CoFeM48

A novel "core/shell" structured magnetic nanocomposite, CoFeM48, was synthesized by coating the mesoporous material (MCM-48) on the surface of cobalt ferrite (CoFe2O4) using the self-assembly technology. The crystalline structure, morphology, specific surface area and magnetic properties of CoFeM48 were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area measurement and vibrating sample magnetometer (VSM), respectively. The synthesized nanocomposite exhibited good performance for the removal of five commonly-used sulfonamides (SAs) from water, with the maximum adsorption capacity ranging from 68.9 μg · g-1 (for sulfamethazine) to 99.6 μg · g-1 (for sulfamethizole) at 15 ℃. The adsorption kinetics of SAs onto CoFeM48 could be simulated by the pseudo-second-order model, and the adsorption isotherms could be expressed by Freundlich model. Thermodynamic calculations indicated that the adsorption of SAs onto CoFeM48 was a spontaneous exothermic physical process. Infrared spectra revealed that hydrogen bonding was one of the major interaction forces between the surface functional groups of CoFeM48 and SAs. In addition, the π-π conjugate interaction between the ordered silica structure of MCM-48 and SAs tended to promote the adsorption.