Synthesis, structure and magnetic properties of porous magnetic composite, based on MCM-41 molecular sieve with Fe3O4 nanoparticles

Porous magnetic composites were prepared by the synthesis of molecular sieve MCM-41 in the presence of Fe3O4 nanoparticles with average diameter of 15 run. Nanoparticles were captured by porous silica matrix MCM-41, which resulted in their incorporation, as it was confirmed by TEM, SEM and X-ray diffraction. The materials possessed high surface area (392-666 m(2) g(-1)), high pore volume (0.39-0.73 cm(3) g(-1)) along with high magnetic response (M-s up to 28.4 emu g(-1) at 300 K). Calcination of samples resulted in partial oxidation of Fe3O4 to alpha-Fe2O3. The influence of nanoparticles content on sorption and magnetic properties of the composites was shown. No hysteresis was found for the samples at 300 K; at 5 K, H-C was in the range 370-385 G for non-calcinated samples and 350-356 G for calcinated ones. (c) 2006 Elsevier Inc. All rights reserved.