Aplicação de SiO2 modificado com Zn⁺ NA degradação do glifosato por fotocatalise Heterogênea

Abstract

Brazilian agribusiness, due to its scope, allows Brazil to be one of the largest producers and suppliers of grains and forest products, on the other hand, the use in great demand of agricultural defensives, pesticides, fungicides and herbicides makes it one of the countries that most pollute the environment environment. The scientific community has reported on treatment methods to remove agricultural pollutants from the environment, which can be through physical, biological, chemical processes and advanced oxidative processes (AOPs), which stand out for being efficient in the decontamination of these pesticides and not generating by-products with toxic characteristics. Heterogeneous photocatalysis is a technique that fits into the AOPs, it is based on the use of simple and binary metal oxides. Binary oxides, when compared to simple ones, have improved, more stable and radiation-attenuating properties. Thus, the objective of this study was the preparation and characterization of oxides based on Six-1ZnxO2 (x= 0,10; 0,20 and 0,30 in mol of Zn2+) by the method of polymeric precursors, for application in the degradation of glyphosate. The synthesized oxide powders were characterized by X-Ray Diffraction (XRD), Infrared Spectroscopy (IR) and Absorption Spectroscopy in the UV-Vis Region, Scanning Electron Microscopy (SEM) and Brunauer, Emmett and Teller (BET). Through XRD analysis we can confirm that the oxides were successfully obtained by the method used at 800 °C for 4 hours of calcination. Infrared analyzes confirmed the presence of characteristic bands for Zn-O and O-Si-O and, according to the UV-Vis absorption spectra, the materials showed band gap values of 2,98 – 3,0 eV, close to the literature. SEM micrographs revealed irregular spherical shapes for the catalysts in smaller amounts of Zn2+ passing to rods for catalysts with larger amounts of Zn2+, according to the analysis of the BET method, the increase in the amount of Zn2+ in the SiO2 network promoted a smaller surface area, a smaller volume of pores and a subtle decrease in pore diameter, such factors may influence the performance of these materials in the degradation of the pollutant under study. Regarding the catalytic activity, the SiO2 and Si0,90Zn0,10O2 oxides showed the best performances in the degradation of glyphosate with efficiency of 2 hours of reaction for the solution at the concentration of 10 and 20 ppm.