| A novel method for preparing magnetic carriers, the functionalization of magnetic particles by molecular self-assembly, is described. Oriented and stable monolayers of a dibenzoic acid diamide bolaamphiphile were prepared on the surface of nanosized maghemite (γ-Fe2O3) particles. The nature of the monolayer was characterized by X-ray photoelectron spectroscopy (XPS), while the structure and stability were characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results show that the bolaamphiphile anchors on the surface through chemical bonding between one of the carboxylic head groups and the iron of the maghemite, leaving a pendant carboxylic moiety reactive. A density of the self-assembled films on γ-Fe2O3 was assessed from potentiometric titration studies of the coated particles in dimethylformamide (DMF). Modification of the carboxy-terminated carriers through a reaction with the ligand diethylenetriamine (DETA), using a typical carbodiimide, enabled the preparation of highly selective magnetic carriers. Potentiometric titration of the reacted carriers indicates a 50% yield of DETA-reacted surfaces. An application of the prepared magnetic carriers in the recovery of metals, such as Cu2+ ions from dilute streams, is demonstrated. The efficiency of carriers in the chelation of copper ions was assessed by complexometric titration. Imaging of the prepared magnetic carriers, using an advanced Pt/C replica technique of transmission electron microscopy (TEM), is presented. |
