| Synthesis of MFI-type zeolites with boron and iron in their framework using conventional hydrothermal method
was investigated. The effect of several parameters including gel composition and pH on the crystallization of zeolites
was systematically studied. The prepared samples were characterized by X-ray diffraction (XRD), scanning
electronmicroscopy (SEM), and N2 physical adsorption analysis. The XRD patterns showed that the crystallization
of boroferrisilicate zeolite takes place at pH values higher than 9 with molar ratio of Si/(Fe+B) ≥ 8.3. The crystallinity
and BET surface area of zeoliteswas decreased by increasing the amount of Fe3+ ions in the synthesis gel. The
SEM images revealed that Fe/B ratio of synthesis gel could also influence the morphology of zeolite particles. The
drug loading capacity of boroferrisilicateswith different Fe/B ratioswas evaluated by loading of doxorubicin (DOX)
as amodel drug. Among zeoliteswith Fe/B ratios of 0.5, 1 and 2, higher loading efficiency was achieved for sample
with lower iron content. However, for sample with Fe/B = ∞ which the formation of iron oxide particles on the
external surface of sample was confirmed by XRD and SEM analysis, the DOX loading efficiency was remarkably
high. Since the desorption of DOX molecules from zeolites surface was prevented by the strong interaction between
drug molecules and the surface of heteroatom-substituted zeolites, the release efficiency for all
boroferrisilicate zeolites was low. |