Navegando por Autor "Oliveira, Y. G."

Agora exibindo 1 - 3 de 3

Increase of antimicrobial and photocatalytic properties of silver- doped PbS obtained by sonochemical method
(Springer, 2018-09-08) Paskocimas, Carlos Alberto; Andrade Neto, Nivaldo Freire de; Oliveira, Y. G.; Delmonte, Maurício Roberto Bomio; Motta, Fabiana Villela da
In this work, pure PbS powders doped with silver were obtained in the proportions of 1, 2, 4 and 8 mol% by sonochemical method. Powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV–Vis spectroscopy (UV–Vis) and EPR analysis. The photocatalytic properties were estimated by degradation of methylene blue dye. The antimicrobial properties were studied by the formation of inhibition halos against Escherichia coli and Staphylococcus aureus bacteria and Candida albicans yeast. XRD patterns show that PbS, with a cubic structure, was obtained without the formation of secondary phases. FE-SEM analysis indicates loss of the cubic aspect of PbS samples as the Ag+ concentration increases and particle size reduces. The defects generated by the substitution of Pb2+ by Ag+ increase the photocatalytic activity, where PbS and P8A samples reduced by 25% and 68%, respectively, the MB concentration and significantly increased the antimicrobial activity against E. coli and S. aureus bacteria and C. albicans yeast
Synthesis and characterization of Co2+ and Mn2+ Codoped ZnO nanoparticles obtained by the sonochemical method: photocatalytic and antimicrobial properties
(Springer, 2019-06-18) Andrade Neto, Nivaldo Freire de; Oliveira, Y. G.; Delmonte, Maurício Roberto Bomio; Motta, Fabiana Villela da
Nanoparticles of Co2+ and Mn2+ codoped ZnO have been obtained by the sonochemical method. The nanoparticles were characterized by x-ray diffraction, scanning electron microscopy, ultraviolet–visible spectroscopy, N2 adsorption by the Brunauer–Emmett–Teller method and electrical measurements by current–voltage curves. The photocatalytic property was analyzed against the methylene blue (MB) dye and the antimicrobial properties were estimated against the Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria by the disc diffusion method. The results indicate that ZnO powders were obtained without the formation of secondary phases, with initial nanoplate morphology, which is lost with doping. The codoped sample had a five-fold higher electrical response, reduced the MB dye concentration by 10% and increased the inhibition halo by 3 cm and 4 cm against S. aureus and E. coli, respectively, compared to bare ZnO
Synthesis, characterization, optical properties investigation and reusability photocatalyst capacity of AgCl‐xGO composite
(Springer, 2019-07-20) Andrade Neto, Nivaldo Freire de; Oliveira, Y. G.; Nascimento, José Heriberto Oliveira do; Carvalho, Bruno Ribeiro de; Delmonte, Maurício Roberto Bomio; Motta, Fabiana Villela da
In this work, we report the photocatalytic reuse study of AgCl-xGO composite with diferent GO concentration (x=1, 2, 4 and 8 mass %) to degrade cationic dyes. X-ray difraction and scanning electron microscopy analysis were performed to characterize the formation and morphological features of the synthesized AgCl-xGO composite. Raman spectroscopy and UV–Vis studies were used to characterize the AgCl optical properties. It was observed an Increasing in the photocatalytic efciency due to interface created by AgCl-GO composite associated to the impeding recombination of the electron–hole pair. Additionally, we notice that after 3 min of exposure to UV radiation, the AgCl-8%GO composite completely degraded the methylene blue dye while pure AgCl sample degraded 75.3%. The AgCl-8%GO composite showed stable photocatalytic activity even after the fourth cycle, indicating a high potential for application in consecutive photocatalytic cycles

SIGAA

Navegando por Autor "Oliveira, Y. G."