Estudo das propriedades fotocataliticas e bactericidasdo composito O Ag3PO4/NiCo- METAL-ORGANIC FRAMEWORK irradiado por diodo emissor de luz branca

Abstract

Nowadays, pathogenic resistant microorganisms such as viruses, bacteria, fungi, and protozoa are an increasingly evident threat due to the contamination of water by organic pollutants, making it necessary to develop new materials with bactericidal properties for the treatment of contaminated water. This work aimed to synthesize silver phosphate (Ag3PO4) crystals and nickel and cobalt metalorganic framework (NiCo-MOF) nanosheets to produce Ag3PO4/NiCo-MOF composites to check their photocatalytic and bactericidal activity. Ag3PO4 was synthesized using the kinetic control method and NiCo-MOF using the ultrasonication method. The composites were synthesized by mixing the pure materials in different proportions. The structural, optical, and morphological characterization of the materials was carried out using X-ray Diffraction (XRD), Diffuse Reflectance Spectroscopy (DRS), Infrared Fourier Transform (IR-FT), and field emission scanning electron microscopy (SEM-FEG). To determine the photocatalytic efficiency, photocatalytic tests were carried out with the dye Rhodamine B and radical scavengers to identify which reactive species are most prevalent. Bactericidal activity tests were carried out using the bacteria Staphylococcus aureus (S. aureus) ATCC 29213 and Escherichia coli (E. coli) ATCC 25922, using the serial dilution method in 96-well microplates, incubated for 24 hours with and without light, to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). The X-ray Diffraction (XRD) patterns of Ag3PO4 confirm the formation of crystals without a deleterious phase, the XRD pattern of NiCo- MOF shows the signals of the Ni-MOF phase, the XRD of the composites shows only the Ag3PO4 planes, due to the low diffraction intensity of NiCo-MOF, the displacement of the diffraction planes indicates interaction between the structures. Fourier Transform Infrared (FT-IR) spectra showed the main vibrational modes of each structure. Field Emission Scanning Electron Microscopy (SEM-FEG) images show the predominant tetrahedral morphology for Ag3PO4, and sheets for NiCo-MOF, and Ag3PO4/NiCo-MOF showed the presence of both morphologies. In the DRS, the materials showed band gap energy values between 2.32 eV and 3.60 eV, with Ag3PO4 being the material with the lowest value. The Rhodamine B dye degradation tests carried out under LED irradiation of pure Ag3PO4 showed 98.9% degradation in 15 minutes, while Ag3PO4/UMOFNs 5% showed 99.5% degradation in 20 minutes. The bacteria showed greater susceptibility in the presence of Ag3PO4 with Minimum Bactericidal Concentration (MBC) values of 64 􀈝g/mL when irradiated by white LED (􀈜max: 460, 500, and 625 nm). The Ag3PO4/NiCo-MOF-5% composite, when incubated without light, showed an MBC value of 64 􀈝g/mL (Staphylococcus aureus) and 32 􀈝g/mL (Escherichia coli). The better activity of Ag3PO4 when incubated under light is related to the formation of reactive oxygen species, and the bactericidal action of the composite may be related to the controlled release of silver ions into the solution, causing damage to the bacterial membrane in both cases.