Browsing by Author "Novoa, Néstor"

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Antibacterial and antifungal properties of electrospun recycled PET polymeric Fibers functionalized with zinc oxide nanoparticles
(2021) Cruzat Contreras, Christian Américo; Vázquez Ordóñez, Katherine Anabel; Vanegas Peña, María Eulalia; Arrué, Ramón Francisco; Novoa, Néstor; Vanegas Peña, Paúl Fernando
Currently, to reduce the environmental problems associated with plastic waste, methods are being sought to use this waste as raw materials in different applications, such as fibers. In addition, to improve these materials and provide different properties, nanoparticles (NPs) are incorporated. In the present work, polymeric fibers made of recycled polyethylene terephthalate (r-PET) from post-consumer water bottles, functionalized with 0%, 1.5%, 3% and 6% zinc oxide nanoparticles (ZnO-NPs) in function of r-PET weight, were elaborated to evaluate their antibacterial and antifungal characteristics. The ZnO-NPs were synthesized by the solvothermal method, obtaining particles with a mean diameter of 38.15 nm, while the fibers were obtained by electrospinning with a diameter range between 200–5000 nm. The functionalized fibers were carried out against Escherichia coli and Bacillus subtilis through the agar diffusion method, obtaining the highest inhibition halo at 6% w/w ZnO-NPs, being 26.5 mm and 34.25 mm, respectively. In addition, the same method was used to evaluate the antifungal activity of Penicillium s.p. and Fusarium graminearum, observing antifungal properties due to the presence of nanoparticles in the fibers.
Potential biopolymer adsorbent functionalized with Fe3O4 nanoparticles for the removal of Cr(VI) from aqueous solution
(2022) Vanegas Peña, María Eulalia; Castro Tamay, Pablo Reinaldo; Novoa, Néstor; Arrué, Ramón; Juela Quintuña, Diego Marcelo; Cruzat Contreras, Christian Américo
In the present study, an adsorbent with a synergistic effect was developed from chitosan (CS) and Fe3O4 nanoparticles (Fe3O4 Nps) to remove Cr(VI) from aqueous solutions. The Fe3O4 Nps were synthesized by co-precipitation and were characterized by TEM. The CS/NPs composites were prepared by electrospinning technique and analyzed by SEM, FT-IR, DSC, and TGA. In the batch system, the influence of Fe3O4 Nps content, pH, contact time, Cr(VI) initial concentration, adsorbent dosage, and the temperature was investigated; the Cr(VI) concentration was determined using a colorimetric method by UV–Vis spectroscopy. The Fe3O4 Nps presented a quasi-spherical shape and an average size of 18 nm, with a low particle distribution. The SEM analysis reveals the presence of highly porous, interconnected micrometric structures. The optimal adsorption conditions were 1% load of Fe3O4 Nps by weight of CS, pH 3, 25 °C, and equilibrium was reached at just 9 min. Besides, the adsorption is favored by increasing Cr(VI) initial concentration and adsorbent dosage. The studies of reaction kinetics and adsorption equilibrium showed that the experimental data were better fitted to the Pseudo-second-order and Langmuir isotherm models, establishing monolayer formation and chemisorption. The maximum adsorption capacity of CS/ Fe3O4 Nps was 440.75 mg/g, which indicates a high affinity of the adsorbent for Cr(VI). Finally, a kinetic diffusion study established that intraparticle diffusion, and in particular surface diffusion, are important resistances in the transport of Cr(VI) from the liquid phase to the active site.