Synthesis and characterization of iron photocatalysts supported on microporous zeolites

ZSM11 and BETA zeolitic materials were synthesized by the hydrothermal method and were further impregnated with a 6 wt% of iron and characterized by different physicochemical techniques in order to be employed in the photocatalytic degradation of methyl orange (MO). Matrices structures and crystallinity were verified by X Ray Diffraction (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR), even for modified zeolites. XRD patterns showed the characteristic signals at 2 theta=7, 9, 23 and 24 degrees for ZSM11 matrix, and 2 theta= 7-8 degrees and 21- 22 degrees, for BETA. According to BET results, specific surface area were 392 m(2)/g for ZSM11 and 585 m(2)/g for BETA. In both cases, an area reduction with metal incorporation were obtained. Iron content was confirmed by Atomic Absorption (AA) spectroscopy, finding similar values than the theoretical ones. Additionaly, iron signals (0,5 y 6,5 KeV) were detected by SEM EDX. Band gap energies of the materials were calculated employing Diffuse Reflectance Spectroscopy- UVvis (DRS-UVvis), obtaining similar values than alpha-Fe2O3. A reduction of the band gap energy in comparison with the correspondent material was also found by this technique. The materials were further evaluated as catalysts for MO photodegradation obtaining a 96 % and 56% of degradation for Fe-ZSM11 and Fe-BETA, respectively.