PREPARATION AND CHARACTERIZATION OF MAGNETIC COMPOSITES BASED ON A NATURAL ZEOLITE

A magnetic composite was prepared by wet-impregnating a powder of a natural zeolite with a magnetic Fe oxide-containing synthetic material. Both starting materials were first characterized with X-ray diffraction, scanning electron microscopy, Mossbauer spectroscopy, and by isoelectric-point using vibrating-sample magnetometry. The synthetic Fe oxide-containing material was characterized as a mixture of magnetite (Fe3O4) and goethite (alpha-FeOOH). From the Fe-57 Mossbauer analysis, the relative subspectral area for magnetite corresponds to 93(2)%; the remaining spectrum is assignable to goethite. After the impregnation process, magnetite was still identified in the composite material as a magnetic layer surrounding the zeolite particles; no magnetically ordered goethite could be detected. The Mossbauer pattern for this sample indicates a much more complex structure than for the precursor material, based on Fe oxides, with some more altered magnetite and an intense central doublet of(super)paramagnetic Fe3+., probably due to small Fe (hydr)oxides and/or to a residual contribution of Fe-bearing species from the starting zeolite material. The composite preparation procedure also promoted the change of the characteristic A-type zeolite to mordenite. The resulting magnetic composite presented a magnetic coercivity of as much as 0.140 A m(-1), at 77 K. The final composite is now being evaluated as an adsorbent: results to date confirm that this novel magnetic material may have applications in the remediation of contaminated water bodies.