Estudo da atividade fotocatalítica do ZnO através da degradação do herbicida 2,4-D e avaliação toxicológica utilizando Artêmia fransciscana.

Abstract

Environmental problems such as water pollution are continually increasing, so a particularly important global issue is to develop water treatment processes that are more efficient in degrading persistent organic pollutants and that are also cost-effective. In this sense, advanced oxidative processes (AOP), in particular, heterogeneous photocatalysis have stood out, since, in fact, it degrades organic and inorganic substances. Thus, the zinc oxide (ZnO) catalyst was synthesized by the modified Pechini method and its efficiency was verified from the removal of the 2,4-D herbicide, through heterogeneous photocatalysis, varying the kinetic parameters of the reaction. Thus, a catalyst was obtained that showed excellent catalytic activity, which is a monophasic oxide with high crystallinity, with a bandgap of 3.12 eV and degradation efficiency of the 2,4-D herbicide around 85% after 150 min of reaction, under mean solar irradiation of 1898.83 kJ m2

, 0.8 gL-1 of ZnO, 43.0 mg.L-1

of 2.4-D and pH 5.6. In the presence of artificial UV-Vis radiation, the catalyst achieved a performance of 92.8% removal of 2,4-D in 180 minutes of reaction, with 0.8 g.L-1

of ZnO, 20.0 mg.L-1

of 2,4-D, pH 5.6 and radiation rate of

2692.8 kJ.m-2

. The acute toxicity of concentrations of 41.0 mg.L-1

and 58.0 mg.L-1

was also evaluated. 2,4-D, treated or not with heterogeneous photocatalysis on Artemia franciscana, where toxic effects of 2,4-D and its first and main degradation by-product, 2,4-dichlorophenol, were observed. This suggests that the catalyst produced has a high potential to be used in the treatment of effluents contaminated by micropollutants, via heterogeneous photocatalysis.