Study of the photocatalysis and increase of antimicrobial properties of Fe3+ and Pb2+ co-doped ZnO nanoparticles obtained by microwave-assisted hydrothermal method

The difficulty in treating organic effluents and increasing the resistance of microorganisms to conventional treatments promotes the development of new materials for these applications. In this work, it was obtained ZnO co-doped with Fe2+ and Pb2+ (ZnO:xFe:yPb, with x and y varying between 0, 1, 3 and 7 mol%) by microwave-assisted hydrothermal method with a reaction temperature of 140 degrees C for 30 min. The powders were characterized by X-ray diffraction (XRD), field-scanning electron microscopy (SEM), Brunauer-Emmett-Teller method (BET), ultraviolet diffuse reflectance spectroscopy (DRS-UV), X-ray fluorescence analysis (XRF) and Fourier transform infrared spectroscopy (FTIR). Photocatalytic properties were estimated by the degradation of the methylene blue dye when subjected to UV radiation. The antimicrobial properties were investigated by the formation of inhibition halos against E. coli and S. aureus bacteria. The XRD patterns show that there was no formation of secondary phases, obtaining only the ZnO phase, with hexagonal structure. Through the XRD, it can be seen that the intensity of the characteristic peaks is also reduced as the dopant concentration increases, indicating the appearance of defects in the crystalline lattice. SEM images show that an increase in the dopant concentration promotes a loss in the morphology of ZnO nanoparticles, accompanied by a reduction in their mean size. The co-doping reduces the photocatalytic activity of ZnO against the methylene blue dye, but increases the antimicrobial activity against E. coli and S. aureus bacteria.