Aplicação de nanopartículas de WO3 na fotodegradação do corante Rodamina B
Data
2022-12-14
Autores
Ferreira, Ronan Bedia 
Orientadores
Mazzo, Tatiana Martelli
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
A intensa atividade industrial e sua constante evolução nas últimas décadas trouxe diversos benefícios para o ser humano como conhecemos hoje. A fim de remediar os impactos negati-vos decorrentes dessa evolução, a ciência avança cada vez mais, propondo métodos e tecnolo-gias capazes de reverter ou ao menos amenizar esses prejuízos. Nos últimos anos, cientistas de todo o mundo voltaram suas atenções para as aplicações de nanopartículas visando encontrar formas eficientes de degradar moléculas tóxicas oriundas de processos industriais. Uma dessas moléculas é a Rodamina B, importante corante orgânico utilizado na indústria têxtil pertencen-te a classe dos xantenos, altamente solúvel em água e toxicidade associada às irritações nos olhos e pele, ainda com potencial carcinogênico. O Trióxido de Tungstênio é um semicondutor não tóxico, quimicamente e fotoquimicamente estável em meios aquosos com um bandgap estreito na faixa de 2,6 e 3,5 eV. Esse óxido possui fotopropriedades catalíticas, químicas, elétricas e antibacterianas podendo ser ativado por irradiação de luz visível. Neste trabalho foram utilizados métodos de caracterização ótica por DRX e MEV-FEG para as análises mor-fológicas dos nanocristais de WO3 e WO3 dopado com prata, sintetizados a partir do método hidrotérmico assistido por microondas, espectroscopia difusa para medição da energia de ban-dgap das amostras e espectroscopia de absorção com luz UV-vis para a análise de fotodegra-dação do corante Rodamina B. Através das análises, pôde-se observar a diferença morfológica dos cristais de WO3 puros e dopados com prata, demonstrando que no segundo caso houve maior porosidade e desordem estrutural. A espectroscopia de reflectância difusa indicou que o bandgap da amostra dopada com Ag é menor decorrente da desorganização estrutural e do tipo de morfologia. Por fim, verificou-se a capacidade de fotodegradação da RhB em ambas as amostras, essas capazes de degradar 70% do corante em 60 minutos, no entanto a amostra de WO3 dopado com prata degradou cerca de 60% em 20 minutos enquanto que o WO3 puro alcançou um pouco menos de 40% no mesmo tempo, resultado esperado devido a presença de defeitos observada pelas técnicas de DRX, refletância difusa e MEV-FEG.
The intense industrial activity and its constant evolution in the last decades brought several benefits to human beings as we know them today. To remedy the negative impacts arising from this evolution, science is advancing more and more, proposing methods and technologies capable of reversing or at least mitigating these losses. In recent years, scientists around the world have turned their attention to the applications of nanoparticles, among them their capac-ity as catalytic nanoparticles, to find efficient ways to degrade toxic molecules from industrial processes. One of these molecules is Rhodamine B, an important organic dye used in the tex-tile industry, belonging to the class of xanthenes, highly soluble in water and toxicity associat-ed with eye and skin irritation, even with carcinogenic potential.Tungsten Trioxide is a non-toxic semiconductor, which is chemically and photochemically stable in aqueous media with a narrow bandgap in the range of 2.6 and 3.5 eV. This oxide has catalytic, chemical, electrical, and antibacterial photoproperties and can be activated by irradiation of visible light. In this work, methods of optical characterization by XRD and SEM were used for the morphological analysis of WO3 and silver-doped WO3 nanocrystals, synthesized from the microwave-assisted hydrothermal method, diffuse spectroscopy to measure the bandgap energy of the samples and absorption spectroscopy with UV-vis light for the analysis of photodegradation of the dye Rhodamine B.Through the analysis, it was possible to observe the morphological difference between pure and silver-doped WO3 crystals, demonstrating that in the second case there was greater porosity and structural disorder. The diffuse reflectance spectroscopy indi-cated that the bandgap of the sample doped with Ag is smaller due to the structural organiza-tion and the type of morphology. Finally, the photodegradation capacity of RhB was verified in both samples those capable of degrading 70% of the dye in 60 minutes, however the WO3 sample doped with silver degraded about 60% in 20 minutes while the WO3 pure reached a little less than 40% in the same time, an expected result due to the presence of defects ob-served by the XRD techniques, reflectance diffuses and SEM.
The intense industrial activity and its constant evolution in the last decades brought several benefits to human beings as we know them today. To remedy the negative impacts arising from this evolution, science is advancing more and more, proposing methods and technologies capable of reversing or at least mitigating these losses. In recent years, scientists around the world have turned their attention to the applications of nanoparticles, among them their capac-ity as catalytic nanoparticles, to find efficient ways to degrade toxic molecules from industrial processes. One of these molecules is Rhodamine B, an important organic dye used in the tex-tile industry, belonging to the class of xanthenes, highly soluble in water and toxicity associat-ed with eye and skin irritation, even with carcinogenic potential.Tungsten Trioxide is a non-toxic semiconductor, which is chemically and photochemically stable in aqueous media with a narrow bandgap in the range of 2.6 and 3.5 eV. This oxide has catalytic, chemical, electrical, and antibacterial photoproperties and can be activated by irradiation of visible light. In this work, methods of optical characterization by XRD and SEM were used for the morphological analysis of WO3 and silver-doped WO3 nanocrystals, synthesized from the microwave-assisted hydrothermal method, diffuse spectroscopy to measure the bandgap energy of the samples and absorption spectroscopy with UV-vis light for the analysis of photodegradation of the dye Rhodamine B.Through the analysis, it was possible to observe the morphological difference between pure and silver-doped WO3 crystals, demonstrating that in the second case there was greater porosity and structural disorder. The diffuse reflectance spectroscopy indi-cated that the bandgap of the sample doped with Ag is smaller due to the structural organiza-tion and the type of morphology. Finally, the photodegradation capacity of RhB was verified in both samples those capable of degrading 70% of the dye in 60 minutes, however the WO3 sample doped with silver degraded about 60% in 20 minutes while the WO3 pure reached a little less than 40% in the same time, an expected result due to the presence of defects ob-served by the XRD techniques, reflectance diffuses and SEM.
Descrição
Citação
FERREIRA, Ronan Bedia. Aplicação de nanopartículas de WO3 na fotodegradação do corante Rodamina B. 2022. 35 f. Trabalho de conclusão de curso (Graduação em Bacharelado Interdisciplinar em Ciência e Tecnologia do Mar) - Instituto do Mar, Universidade Federal de São Paulo, Santos, 2022.