Novos materiais multifuncionais para aplicação em fotocatálise
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Data
2016-03-30
Autores
Silveira, Gisele Santos [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Este trabalho teve como objetivo a preparação, a caracterização estrutural e análise do potencial fotocatalítico de nanopartículas do tipo core@shell de ZnO@Cr, ZnO@Ni e dos compósitos de C/Zn@Cr e C/ZnO@Ni, combinando nanopartículas e carbono amorfo. As nanopartículas core@shell foram sintetizadas pelo método Pechini Modificado e os compósitos, contendo carbono amorfo, pelo método de Pirólise Parcial. Os materiais sintetizados foram caracterizados por análise termogravimétrica (TG), microscopia eletrônica de varredura (MEV) e microscopia eletrônica de transmissão (MET), difração de raios X (DRX), espectroscopia de absorção no infravermelho (I.V.), espectroscopia no ultravioleta-visível (UV-VIS) e medidas de condutividade térmica. As caracterizações estruturais mostraram a formação de um sistema do tipo core@shell, onde o recobrimento é essencialmente amorfo. Uma pequena fração de solução sólida foi identificada na interface núcleo/revestimento, bem como uma redução nos valores de energia de band gap, em função dos recobrimentos. Para os compósitos, as caracterizações estruturais mostraram a manutenção das nanopartículas core@shell em meio a uma matriz de carbono com estrutura do tipo turbostrática. A análise do potencial fotocatalítico mostrou que, os recobrimentos com Cr e Ni e a matriz de carbono, de modo geral, atuaram positivamente sobre a fotoatividade do ZnO. Foram obtidas taxas de descoloração entre 64 e 98%, sendo o melhor resultado obtido para a descoloração do corante basic blue 41 na presença das nanopartículas ZnO@Ni. Em todos os experimentos, a reação de descoloração dos corantes, seguiu uma cinética do tipo primeira ordem.
This work aimed the preparation, structural characterization and analysis of photocatalytic potential of ZnO@Cr and ZnO@Ni core@shell type nanoparticles and of C/Zn@Cr and C/ZnO@Ni composites, combining the nanoparticles and amorphous carbon. The core@shell nanoparticles were synthesized by the Pechini Modified method and the composites, containing amorphous carbon, were synthesized by the Partial Pyrolysis method. The synthesized materials were characterized by thermogravimetric (TG), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis) and thermal conductivity measurements. The structural characterization showed the formation of a core@shell type system where the coating is essentially amorphous. A small fraction of solid solution was identified in the interface core/coating, as well as a reduction in the band gap energy values as a function of the coatings. For the composites, structural characterizations showed the maintenance of the core@shell nanoparticles amid a carbon matrix with turbostratic type structure. The analysis of the photocatalytic potential showed that the coatings with Cr and Ni and carbon matrix acted positively on the photoactivity of ZnO. Discoloration rates between 64 and 98% were obtained. The best result was acquired for the discoloration of the basic blue 41 dye in presence of ZnO@Ni nanoparticles. In all experiments, the reaction of discoloration of dyes followed a kinetic of the first order type.
This work aimed the preparation, structural characterization and analysis of photocatalytic potential of ZnO@Cr and ZnO@Ni core@shell type nanoparticles and of C/Zn@Cr and C/ZnO@Ni composites, combining the nanoparticles and amorphous carbon. The core@shell nanoparticles were synthesized by the Pechini Modified method and the composites, containing amorphous carbon, were synthesized by the Partial Pyrolysis method. The synthesized materials were characterized by thermogravimetric (TG), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis) and thermal conductivity measurements. The structural characterization showed the formation of a core@shell type system where the coating is essentially amorphous. A small fraction of solid solution was identified in the interface core/coating, as well as a reduction in the band gap energy values as a function of the coatings. For the composites, structural characterizations showed the maintenance of the core@shell nanoparticles amid a carbon matrix with turbostratic type structure. The analysis of the photocatalytic potential showed that the coatings with Cr and Ni and carbon matrix acted positively on the photoactivity of ZnO. Discoloration rates between 64 and 98% were obtained. The best result was acquired for the discoloration of the basic blue 41 dye in presence of ZnO@Ni nanoparticles. In all experiments, the reaction of discoloration of dyes followed a kinetic of the first order type.
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Palavras-chave
ZnO, Core@shell, Carbono amorfo, Fotocatálise, Vermelho de fenol, Basic Blue 41, ZnO, Core@shell, Amorphous carbon, Phenol red dye, Basic blue 41