MARGARIDA SZURKALO
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Artigo IPEN-doc 21345 Influência do tratamento com moléculas auto-organizáveis no comportamento de corrosão da liga de alumínio 10502008 - SZURKALO, MARGARIDA; ASSIS, SERGIO L. de; COSTA, ISOLDAMoléculas auto-organizáveis são compostos de baixa solubilidade capazes de alterar as propriedades superficiais de substratos metálicos pela formação de camadas auto-organizadas. Essas moléculas aumentam a resistência à corrosão e promovem uma boa aderência entre revestimentos orgânicos e o substrato. Em razão disso, elas têm sido consideradas como uma alternativa ao tratamento de cromatização na preparação da superfície de ligas de alumínio para revestimento. Esse trabalho investiga a influência do tratamento da superfície em solução com moléculas auto-organizáveis na resistência à corrosão da liga de alumínio 1050. A resistência à corrosão dessa liga, seja com a superfície tratada ou sem tratamento com moléculas autoorganizáveis foi avaliada por ensaios de espectroscopia de impedância eletroquímica e curvas de polarização em solução de sulfato de sódio, à temperatura ambiente. Amostras cromatizadas foram também ensaiadas nas mesmas condições que as amostras tratadas com moléculas autoorganizáveis, e os resultados foram comparados. Os resultados obtidos indicaram aumento na resistência à corrosão das amostras tratadas com as moléculas auto-organizáveis em relação às amostras sem tratamento, mas a resistência à corrosão das primeiras foi bem inferior à das amostras cromatizadas.Resumo IPEN-doc 25476 UV–Vis photocatalytic performance of the S-doped TiO2 and TiO2 thin films for water treatment2018 - BENTO, R.T.; SZURKALO, M.; OLIVEIRA, E.C.; CORREA, O.V.; PILLIS, M.F.TiO2 films have been widely used as catalysts in oxidative processes in order to degrade organic contaminant. However, without the presence of a dopant material, its photocatalytic activity is limited only in the region of ultraviolet radiation (UV), due to its high-energy band gap. In this present research, anatase TiO2 thin films were grown on borosilicate substrates by metalorganic chemical vapor deposition (MOCVD) at 400ºC. To make the semiconductor active in the visible light region, sulfur doped TiO2 films were prepared by means of a thermochemical treatment carried out in a tubular oven, under atmosphere of H2S at 50ºC for 60 minutes. The films were characterized by XRD, AFM, FE-SEM and XPS technique. The photocatalytic behavior of the films was evaluated by methyl orange dye degradation under UV-Vis irradiation for 300 minutes. The photocatalytic tests were realized in a reactor illuminated by two tubular UV lamps (352 nm), and in a reactor illuminated by visible light (400-700 nm) on different intensities, both containing 40 mL of the dye solution. The results showed that the S-TiO2 films present promising photocatalytic efficiency. Without the presence of the catalyst, there was no degradation of the methyl orange dye under UV-Vis irradiation. Non-doped TiO2 films do not exhibited photocatalytic activity under visible light. It was possible to observe that the visible light intensity influences the doped films photocatalytic performance.Artigo IPEN-doc 25006 Characterization and photocatalytic behavior of TiO2 thin films grown by MOCVD process2017 - BENTO, RODRIGO T.; OLIVEIRA, EDUARDO C. de; SZURKALO, MARGARIDA; CORREA, OLANDIR V.; PILLIS, MARINA F.This research aims to evaluate the influence of the thickness on the photocatalytic behavior of TiO2 thin films grown at 400ºC by metalorganic chemical vapor deposition. Titanium dioxide films with 280 and 468 nm of thickness were grown on borosilicate substrates. The photocatalytic behavior was evaluated by monitoring the degradation of methyl orange dye under UV light for 2h. The results show that both films presented anatase crystalline phase and that increasing the thickness the grain size and the roughness were also increased. The best photocatalytic performance was attributed to the film of 468 nm of thickness that exhibited 40% of dye degradation after 2h under UV light.Artigo IPEN-doc 25005 Synthesis and characterization of TiO2 films obtained by sol-gel method2017 - SZURKALO, MARGARIDA; OLIVEIRA, EDUARDO C. de; CORREA, OLANDIR V.; BENTO, RODRIGO T.; PILLIS, MARINA F.Borosilicate coated titanium dioxide thin films were produced by the sol-gel method. The films were calcinated at 450°C for 20 minutes for crystalization. X-ray diffration analyses show that before the heat treatment the film was amorphous and after that it crystallized in anatase phase presenting mean grain size of 34 nm and RMS roughness of 8 nm. The crystallized film was used as photocatalist in the degradation of methyl orange dye presenting an efficiency of 25% after 2h under UV light.Artigo IPEN-doc 24951 Morphological characterization of N-doped TiO2 thin films2017 - OLIVEIRA, EDUARDO C. de; SZURKALO, MARGARIDA; CORREA, OLANDIR V.; BENTO, RODRIGO T.; PILLIS, MARINA F.Metallorganic chemical vapor deposition was used to grown TiO2 and N-doped TiO2 on borosilicate substrates at 400°C. Titanium isopropoxide IV was used as titanium and oxygen precursors and ammonia as nitrogen source. Analyses by atomic force microscopy showed that both films presented rounded well-defined grains. The results showed that nitrogen doping resulted in a decrease in the mean grain size and in the surface roughness.