Síntese, caracterização e atividade fotocatalítica de Ag3PO4/SBA-15 na degradação da ciprofloxacina sob irradiação policromática

Abstract

Ciprofloxacin is a fluoroquinolone that is sensitive to the conventional process of degradation and, in the environment, causes bacterial resistance. This study evaluates the ciprofloxacin degradation over the solids silver phosphate and SBA-15 under polychromatic irradiation. In the characterization of the solids, the X-Ray diffraction patterns (XRD) showed good crystallinity degree for both Ag3PO4 and the mesoporous hexagonal structure of the SBA-15. Besides, The Rietveld refinement was used in the phase index of Ag3PO4 showing a body-centred cubic structure space group P43̅̅̅̅n (218) for the Ag3PO4. The active vibrational modes related to the characteristic groups of the solids were identified by using Raman spectroscopy and Fourier Transform Infrared Spectroscopy. The images obtained by field-emission scanning electron microscopy (FE-SEM) revealed that cubic forms predominate as well as the average size of the particles, 498 nm for Ag3PO4. The UV-vis diffuse reflectance spectroscopy (DRS) showed that the Ag3PO4 has gap band energy (EBG) 2.25 eV, Ag3PO4/SBA-15(5%), 2.23 eV, Ag3PO4/SBA-15(10%), 2.21 eV and the Ag3PO4/SBA-15(20%), 2.14 eV. The reduction on the specific surface area values (BET) of 582.1 m2 g-1 (SBA-15) for 373.3 m2 g-1 (Ag3PO4/SBA-15(20%)) associated with a slight variation in the average pore diameter showed that the Ag3PO4 was impregnated on the external surface of the SBA-15. The photocatalytic tests showed that when the samples containing Ag3PO4 are irradiated, silver oxide and silver metal are originated from those samples, highlighting the photo-instability of the material. Even so, the photodegradation of CIP under polychromatic irradiation for 210 min, reached yields of 46.51, 56.18, 61.69 and 78,51% over the Ag3PO4/SBA-15(5%), Ag3PO4/SBA-15(10%), Ag3PO4/SBA-15(20%) and Ag3PO4, respectively.