The diffraction pattern of Fe3O4 (not shown) confirmed the
presence of only one phase, corresponding to magnetite with
a lattice parameter a = 8.357 Å and a crystallite size of 16.6 ±
0.2 nm. The diffraction pattern of MGNC (not shown)
confirmed the presence of a graphitic phase, in addition to the
metal phase, suggesting that Fe3O4 nanoparticles were
successfully encapsulated within a graphitic structure during
the synthesis of MGNC. The core-shell structure of MGNC is
unequivocally demonstrated in the TEM micrograph shown in
Fig. 1b. Characterization of the MGNC textural and surface
chemical properties revealed: (i) stability up to 400 oC under
oxidizing atmosphere; (ii) 27.3 wt.% of ashes (corresponding
to the mass fraction of Fe3O4); (iii) a micro-mesoporous
structure with a fairly well developed specific surface area
(SBET = 330 m2 g-1); and (iv) neutral character (pHPZC = 7.1). In
addition, the magnetic nature of MGNC (Fig. 2) is an additional
advantage for possible implementation of in situ magnetic
separation systems for catalyst recovery
