Fast photocatalytic degradation of pharmaceutical micropollutants and ecotoxicological effects

Abstract

Aqueous solutions of ciprofloxacin (CP) and ibuprofen (IBP) in the presence of LaFeO3 photocatalyst, of H2O2, and of both LaFeO3 and H2O2 were irradiated under visible light. The degradation rate in the presence of both LaFeO3 and H2O2 after 5 h irradiation was more than 90% for CP and 40% for IBP, much higher than that with only H2O2 under visible light. For the sake of comparison, the experiments were also carried out in the dark, and both CP and IBP were not significantly converted. The degradation rate was enhanced by the simultaneous presence of small concentration of LaFeO3 (130mgL-1) and H2O2 (0.003M). However, tests on the aquatic acute toxicity indicate that the degradation products of CP and IBP induce toxic effects on aquatic organisms, consequently indicating incomplete detoxification after 5 h irradiation. The main degradation product of IBP was 4-isobutylacetophenone (4-IBAP), detected in the irradiated solutions by using UV/vis spectrophotometry. 4-IBAP was more toxic and showed a slower photocatalytic degradation than the parent compound. On the contrary, the toxicity of CP degradation products, although not negligible, was comparable to that of CP itself.