Avaliação da toxicidade aguda de fotocatalisadores de nióbio em Daphnia magna e Artemia salina

Abstract

The niobium oxide (Nb2O5) is a white solid, insoluble in water and stable. It's materials are used pure in heterogeneous catalysis, such as promoters and / or carriers. Due to its acidity, is applied to catalytic reactions of dehydration, hydration, esterification, hydrolysis, condensation, alkylation, dehydrogenation, and oxidation. Even if its photocatalytic activity is still unspoilt, its toxicity to the environment needs to be assessed. In this sense, the present work aimed to evaluate the acute toxicity of photocatalysts niobium, with and without the presence of visible light and UVA, using as test organisms Daphnia magna and Artemia salina. The tests consisted of exposure of organisms to different concentrations of photocatalysts, 50, 100, 250, 450 and 650 mg L-1, and acute toxicity was evaluated under three conditions: photoperiod with UVA light (8h / 16h), with photoperiod visible light (8h / 16h) and absence of light. The absence of light allowed to assess whether the compound alone is toxic to organisms and the treatments withlight allowed to verify its phototoxicity. Some studies report the absence of acute toxicity of various photocatalysts often studied in relation to Daphnia magna. However, the assessment of phototoxicity, in other words, the effect that the incident radiation can generate, have been few explored. In the tests performed, no photocatalyst had acute toxicity in the absence of light and, to the wavelengths used here, all niobium photocatalysts, also showed no acute toxicity.