HZSM-5 zeolite supported boron-doped TiO2 for photocatalytic degradation of ofloxacin

Abstract

Boron-doped TiO2 was supported on HZSM-5 zeolite in a sol-gel route to prepare B-TiO2(x%)/HZSM-5 composites. The composites are composed of anatase TiO2 and HZSM-5 zeolite. The crystallite size of anatase TiO2 decreases after loading B-TiO2 on HZSM-5 zeolite. The SEM and TEM images of the composite show the dispersion of the B-TiO2 crystals on the external surface of HZSM-5. The bandgap energies of B-TiO2(x%)/HZSM-5 composites are approximately 3.2 eV. The N2 adsorption-desorption isotherms indicate that B-TiO2 is a mesoporous material and HZSM-5 zeolite is a microporous material. The mesoporous B-TiO2 layer is loaded on the external surface of the zeolite and does not enter into the inner micropores. The XPS results indicate the unchanged chemical environments of both titanium and oxygen in the supported B-TiO2. The B-TiO2(x%)/HZSM-5 composites have higher photocatalytic activity than the unsupported B-TiO2. The optimum B-TiO2 loading content is 20% in the composite, and 55.3% of the original ofloxacin molecules were degraded on the sample after 30 min of irradiation. Photocatalytic oxidation not only causes breaking up of the ofloxacin molecules, but also leads to decomposition of the major functional groups of the ofloxacin molecules.