Fotodegradação do antibiótico levofloxacino promovida por catalisadores porfirínicos

Abstract

The environmental occurrence of emerging pollutants, especially in the aquatic environment, has been reported by researchers in recent years. Due to the world population growth and the intensification of anthropogenic activity, the availability and quality of water have become important to be monitored and evaluated. Among the emerging pollutants, the antibiotic class represents a particular concern, as their presence in the environment can cause an increase in bacterial resistance to treatments already used in clinical medicine and, consequently, lead to the appearance of superbacterias. Thus, this work presents a photocatalytic degradation study of the levofloxacin, an antibiotic, promoted by porphyrinic catalysts in homogeneous and heterogeneous on TiO2 support systems. The levofloxacin photodegradation experiments were performed using a LED lamp (white light, wavelength range 380 and 750 nm). Different types and amount-of-substance of oxidants [PhI(OAc)2, H2O2 and Oxone®] were carried out in aqueous medium systems. Despite being environmentally friendly, systems in the presence of hydrogen peroxide resulted in a low degree of LEV degradation (up to 36% of degradation). In the presence of porphyrins immobilized in titanium dioxide, the best degree for LEV degradation were obtained for catalyst: Oxone® in the molar proportion 1:100 and catalyst:iodobenzene diacetate in the molar proportion 1:200, with 67% and 68% of LEV degradation, respectively. The degradation products were analyzed by mass spectrometry, being observed some products already described in the literature and products that had not been previously reported, and for which structures were proposed. In addition, the toxicity of some products was evaluated using human embryonic kidney (HEK-293) cells; through these experiments, no significant toxicity was observed for the analyzed systems, indicating the potential application of these photocatalytic systems mediated by porphyrinic catalysts for the degradation of LEV and other environmental contaminants.