Fotocatalisador magnético obtido a partir de resíduos industriais para degradação de contaminantes orgânicos

Abstract

In this study, a magnetic photocatalyst was obtained using the following industrial wastes: electric arc furnace dust (PAE), waste pickling acid and tar, which are rich in ZnO, Fe2O3 and organic matter, respectively. Efficiency of the obtained photocatalyst (PAE/C/Fe) was investigated to degrade Remazol Black dye (PR). The following parameters were investigated: catalyst mass (75, 150 and 300 mg), lamp power (15, 36 and 51W), radiation type (UV and solar) and radiation incidence area (44 and 133 cm2

). X-Ray Diffraction analysis showed that the main phases present in PAE are ZnO and MgO. As for PAE/C/Fe, ZnO, MgO, Fe3O4 and amorphous carbon were found. The results obtained by thermogravimetric analysis showed that the photocatalyst has about 23% of PAE. Results of leaching experiments of PAE resulted in the separation of the magnetic fraction rich in coal and iron and a non-magnetic fraction rich in PAE. The SEM images and mapping indicated that the magnetic photocatalyst has a distinct morphology from PAE, with larger particles, which indicate the presence of coal containing zinc and iron on its surface. Results of photocatalytic reactions showed that the efficiencies of PAE/C/Fe (81%) and PAE (73%) regarding Remazol Black dye discoloration are similar. The best results obtained for the photocatalytic reactions were under the following conditions: 51W of UV lamp power, 133 cm2

of radiation incidence area and 300 mg of photocatalyst, which showed the importance of choosing these conditions. Sedimentation kinetics showed a reduction in turbidity of 81 and 62% for PAE/C/Fe and PAE, respectively, showing that the photocatalyst magnetic properties favor the separation from the aqueous medium when a magnetic field is used. The reactions performed with the magnetic and non-magnetic fractions showed that there was low photocatalytic efficiency of FM (10%) due to leaching of PAE from the photocatalyst and good photocatalytic activity of FNM, indicating the majority presence of PAE in its composition. Therefore, it can be concluded that the obtention of the PAE/C/Fe photocatalyst was successful, with further need of adjustments in the process aiming at improving the fixation of the PAE on the C/Fe support.