Síntesis y caracterización de nanopartículas de plata como agente bactericida en aguas residuales

Abstract

Water is the essence of life, the present research work aimed to obtain silver nanoparticles (AgNPs) through green synthesis so that they are evaluated as bactericidal agents in wastewater treatment. For the synthesis of silver nanoparticles, green methodology was used by reduction, where the precursor salt was silver nitrate (AgNO3) and the reducing agent was an aqueous extract of the leaves of Physalis Peruviana L (uvilla). Characterization was performed by Uv-vis spectroscopy and scanning electron microscopy (SEM). The evaluation of the bactericidal activity of the nanoparticles was carried out in vitro in solid culture media (nutritive agar), determining the growth of bacteria in CFU/ml. For the statistical analysis, a 3^2 factorial design was used with two factors, the concentration of AgNPs and the time of exposure to sunlight (1, 2 and 3 hours); being the variable studied the bacterial growth in the medium. The presence of AgNPs was evidenced with the analysis of the Uv-vis spectrum, presenting readings of 412-415 nm. Through the SEM analysis, the morphology of the AgNPs was observed, identifying oval and irregular shapes with a variable size in the range of 7.88—30.47 nm. The best result as a bactericidal agent was obtained by using AgNPs synthesized at a concentration of 1.5 M and with an exposure of 3 hours to sunlight. It was concluded that the silver nanoparticles obtained by a green synthesis act as a bactericidal agent against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Salmonella parathypi, Pseudomona oryzihabitans, Edwardsiella tarda and Shigella flexnery. It is recommended to perform phytochemical tests on the extracts of the silvers to know which metabolites allow the reduction of metals to nanoparticles.