LIBERAÇÃO CONTROLADA E FOTODEGRADAÇÃO DE AGROQUÍMICOS

Abstract

Agrochemicals represent the most widely products found in surface water and groundwater around the world, due to the widespread use in agricultural and urban areas. Atrazine is a herbicide potentially toxic, carcinogenic and mutagenic and has been reported in numerous studies its presence in water sources due to their persistence and mobility. Taking into account this assumption, the present study evaluated the degradation of atrazine in aqueous solution and chitosan solution, using nanostructured catalysts TiO2, ZnO and TiO2/ZnO. In samples supported on chitosan, it was also evaluated controlled release of the herbicide. For degradation, heterogeneous photocatalysis methodology was used, and photodegradation was analyzed in the range 0 to 100 min. The photocatalysis of atrazine in the presence of chitosan demonstrated that the herbicidal degradation occurred significantly less when using the catalyst nanoparticle. The potential for anchoring and the release of atrazine biopolymer for controlled release were evaluated for 56 days, and the results of this study revealed that the chitosan has proved to be an applicable biopolymer in anchoring studies and controlled release of this herbicide. The photocatalytic degradation of atrazine in water was investigated using the same catalysts that showed nanoscale, which was confirmed in the results of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The process was monitored using absorption spectroscopy in the ultraviolet and visible (UVVis) and high-performance liquid chromatography (HPLC). The decrease in absorbance at a specific wavelength of atrazine was observed during the irradiation of samples for all catalysts. The HPLC analysis showed a significant reduction of the herbicide and the formation of other compounds as degradation products. The use of ZnO catalyst was more effective in the degradation of atrazine molecule opposite the other nanoparticles.