Síntese e caracterização de nanopartículas de prata utilizando resíduo de poliuretano como agente redutor

Abstract

Nowadays, it is essential to add value to polymeric waste to promote sustainability. The present study reports on the synthesis of silver nanoparticles (AgNPs) using silver nitrate (AgNO3) as a metallic precursor and polyurethane (PU) waste from mechanical recycling of refrigerators as a reducing agent. Samples were synthesized ranging from 10% to 60% Ag based on the weight of PU. Characterization of the PU waste was performed using thermogravimetric analysis (TG), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. In addition to these techniques, the PU-AgNPs nanocomposites were also characterized using energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and ultraviolet-visible spectroscopy (UV-Vis), then their antimicrobial activity was analyzed through the disk diffusion test. TG analysis revealed that the thermal decomposition of the PU waste occurred by a complex mechanism and the polymer was constituted of methylene diphenyl diisocyanate (MDI) and unidentified polyol. The incorporation of AgNPs into the PU waste affected significantly its thermal stability, confirmed by activation energy value, calculated by Arrhenius’ equation. Diffractograms confirmed the presence of AgNPs in the PU waste, as well as contaminants. Utilizing Scherrer’s equation, the average size of the AgNPs was 10,82 nm. SEM images exhibited a morphology characterized by particles sprinkled with AgNPs and contaminants, which were further confirmed by EDS analysis. The combined use of FTIR and Raman techniques confirmed the AgNPs formation by decrease of intensity of characteristic bands of PU. The disk diffusion test did not reveal antimicrobial activity in the nanocomposites, which suggests the use of other technique to evaluate the antimicrobial activity.