Magnetic Fe2O3–Al2O3 composites prepared by a modified wet impregnation method

Fe2O3–Al2O3 composites were prepared by interaction of acetic acid vapors with iron oxides dispersed on the surface of a sol–gel derived porous alumina. Upon pyrolysis the created iron acetate species were transformed to magnetic iron oxide nanoparticles. The atmosphere which is used during the synthetic procedure affects significantly the nature of the nanoparticles which could be either γ-Fe2O3 or magnetite, or non-magnetic such as α-Fe2O3. X-Ray diffraction, surface area measurements and scanning electron microscopy (SEM) were used for the structural characterization and determination of the sorption properties of the composite material properties. The development of magnetic phases decreases the specific surface area of alumina by seeding of the alumina particles and, in parallel, the coverage of their free surface. Mössbauer spectroscopy, magnetic measurements and transmission electron microscopy (TEM) provide evidence for the formation, size and type of magnetic iron oxide phases.