Resumo (PT):
Abstract (EN):
Photocatalysis has become an attractive process to treat wastewater since it allows a
rapid and efficient degradation of micropollutants in water. A solution of ciprofloxacin
(CIP) was photocatalytically treated by ultraviolet A light (UVA) and titanium dioxide
(TiO2) or zinc oxide (ZnO) nanoparticles. Toxicity of CIP and of the treated CIP
solutions, as well as the toxicity of TiO2 and ZnO irradiated nanoparticles, was
evaluated towards Vibrio fischeri. The lowest concentration of CIP tested, 10 µg L-1
,
leads to 50% of luminescence inhibition. Regarding irradiated nanoparticles, ZnO
presented higher bacteria luminescence inhibition than TiO2, 97 and 38%, respectively.
Due to high toxicity of ZnO, it was only possible to evaluate the CIP solution treated by
UVA/TiO2. Initially, the toxicity decreased with the time of the process, but after 15
min the toxicity increased significantly (55%) and after 45 min of treatment, was 70%.
High-performance liquid chromatography (HPLC) and Fourier transform infrared
spectroscopy (FTIR) analysis proved that the initial decrease of toxicity was caused by
CIP adsorption on catalyst surface, which latter increased due to the generation of byproducts and toxicity contribution of soluble nanoparticles. Ten by-products were
identified by liquid chromatography–mass spectrometry (LC-MS) and the mechanism
of CIP photocatalytic degradation was proposed.
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica
Nº de páginas:
10