THIAGO FERNANDO DOS SANTOS
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Resumo IPEN-doc 31002 Synthesis and characterization of TiO2/GE nanocomposite films deposited on AISI 304 stainless steel2024 - SANTOS, THIAGO F. dos; COTINHO, SAMUEL P.; CORREA, OLANDIR V.; PILLIS, MARINA F.TiO2 and TiO2/exfoliated graphite (GE) films were prepared by the sol-gel method and applied to the surface of AISI 304 stainless steel using the cold spray technique. Initially, natural graphite was subjected to the liquid phase exfoliation process in an aqueous solution containing isopropanol and acetone under UVC irradiation, where expanded graphite was obtained. A solution containing titanium isopropoxide and ethanol was prepared to obtain the sol. The exfoliated graphite, after drying, was then added to the solution in concentrations between 2.5 and 10%, mass/volume ratio. The films were dried in an oven at 100ºC and heat treated at temperatures between 400 and 500 ºC in a tubular oven, under an argon atmosphere. Electrochemical techniques, field emission gun scanning electron microscopy (SEM-FEG), Raman spectroscopy and X-ray diffraction were used to characterize the coatings. The results confirm the formation of the anatase phase in all films and the presence of GE in the composite films. The films have a cracked morphology and TiO2 and GE particles on the surface of the sample were present. The samples were evaluated using potential x time and linear polarization techniques in a 3.5% NaCl aqueous solution at room temperature. The corrosion resistance of the samples increased compared to the substrate, suggesting that the coating act as a physical barrier [1].Resumo IPEN-doc 30995 Synthesis, characterization, and photocatalytic performance of nanostructured ZnO films under UV light2024 - COTINHO, SAMUEL P.; BENTO, RODRIGO T.; SANTOS, THIAGO F. dos; OLIVEIRA, LEANDRO da S.; SANTOS, CAMILA M.G.; SANTOS, DAVI R. dos; CORREA, OLANDIR V.; PILLIS, MARINA F.The limited natural water resources have been contaminated by effluents originating from both the industrial and domestic sectors. A large portion of the available water is consumed in chemical processes in various industrial sectors, including textiles, paper, and leather. Also, the inappropriate disposal of pharmaceuticals and dyes on a large scale results in effluent contamination. Methyl orange is one of the most widely used azo dyes on a large scale. Photocatalysis is a promising green alternative for the removal of organic dyes in wastewater. This research aimed to synthe and characterize nanostructured zinc oxide films to obtain a UV-light-activated photocatalyst capable of degrading organic compounds. The films were obtained using the sol-gel method. Zinc acetate, MEA, and ethanol were kept under constant stirring for 60 minutes at 70°C. The solution obtained was sprayed onto cleaned borosilicate glass substrates by using an airbrush. The samples were then heat treated at temperatures of 450 and 500°C for 45 minutes. The characterization of the films was performed using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), UV-Vis spectrophotometry and wettability. The efficiency of the films was determined by the degradation of a 5 mg.L-1 methyl orange dye water solution at neutral pH, at constant temperature of 20°C, and under two sources of ultraviolet radiation (λ=352 nm) for 300 minutes. The films exhibited hydrophilic characteristics and superficial morphology consisting of spherical nanoparticles. The films showed photoactivity when exposed to UVA radiation, with the best performance in removing methyl orange dye being 48.6% for the film treated at 500°C. This removal value can be attributed to the improvement in the homogeneity of the morphology and thickness of the film treated at 500°C.Resumo IPEN-doc 29392 Síntese e caracterização de filmes nanocompósitos de TiO2/C depositados sobre o aço inoxidável AISI 3042022 - SANTOS, T.F. dos; BENTO, R.T.; CORREA, O.V.; PILLIS, M.F.Filmes de TiO2 e TiO2/C foram preparados pelo método sol-gel e aplicados sobre a superfície do aço inoxidável AISI 304 por spray a frio. Inicialmente, grafite natural foi submetido ao processo de esfoliação em fase líquida, onde se obteve grafite expandido. Para tanto, uma suspensão de grafite em solução aquosa contendo isopropanol e acetona foi irradiada por 2h em luz UVC. Foi preparada uma solução de isopropóxido de titânio e isopropanol para a obtenção do sol. O grafite esfoliado, após secagem, foi então adicionado à solução em concentrações entre 2,5 e 10%, razão massa/volume. Os filmes foram secos em estufa a 100ºC e tratados termicamente a temperaturas entre 400 e 500 ºC em forno tubular, sob atmosfera de argônio. Técnicas de difração de raios X, espectroscopia Raman, espectroscopia UV-visível (UV-vis), microscopia de força atômica e microscopia eletrônica de varredura foram utilizadas na caracterização. Os resultados obtidos confirmam a esfoliação do carbono e a formação da fase anatase em todos os filmes. Resultados de AFM sugerem que a formação da heterojunção semicondutor-carbono, confirmada por espectroscopia Raman, promoveu modificações morfológicas nos filmes, e influenciam o comportamento frente à corrosão do aço revestido, o qual foi avaliado por técnicas de impedância eletroquímica e polarização linear em uma solução aquosa 3,5% NaCl à temperatura ambiente.