Síntese e aplicação biotecnológica de nanoestruturas de óxido de cério (iv), obtidas pelo método hidrotermal de micro-ondas.

• Ano de defesa: 2013
• Autor(a) principal: Santos, Carlos Christiano Lima dos
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraí­ba; BR; Química; Programa de Pós-Graduação em Química; UFPB
• Palavras-chave em Português: Oxido de cério (IV)- dióxido de cério; Nanotecnologia; Biotecnologia - aplicação odontológica; Nanotechnology; Cerium oxide (IV); Hydrothermal; Microwave; Biotechnology; Dentistry; CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/tede/7087

The cerium oxide(IV) (CeO2) has wide application in several areas such as environmental, catalytic, microbiological and its efficiency depends on the morphology and particle size. In this study, they were synthesized by hydrothermal method assisted by microwave under NaOH and NH4OH mineralizers added to a Cerium sulfate tetrahydrate (Ce(SO4)2.4H2O) aqueous solution, at 150°C for 1, 5, 15, 30 and 60 minutes,with and without surfactant that was used as a template for crystal growth. The thermal stability was studied by thermogravimetry (TG). The structural and morphological properties were evaluated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), BET method, infrared spectroscopy (IR), UV-visible spectroscopy (UV-vis) and Raman spectroscopy, Resazurin tests, absorbance, fluorescence and diffusion wells. All samples show XRD peaks corresponding to the plane (1 1 1), (2 0 0), (0 2 2), (3 1 1), (2 2 2) and (4 0 0) of a cube face-centered, fluorite, structure assigned to CeO2 in accordance with the standard JCPDS 34-0394. It is clearly seen that the reflection peaks are broad, indicating that the crystal size is small and should be in nanoscalerange. In addition, data give an indication of the influence of the template and the method for obtaining this nanostructured material. In the Raman spectrum, strong peak around 471 cm-1 was detected, which is the only active mode, of first order, assigned to symmetric O-Ce-O stretching. In the infrared spectra bands between 700 and 400 cm-1 were observed, being related to metal-oxygen vibration.Infrared spectra showed a vibration band between 700 and 500 cm-1related to metal-oxygen vibration (Ce-O). Bands assigned to hydroxyls groups (1100 cm-1) and carbonates (1530, 1050 and 850 cm-1) were also observed independently of the presence of the PEG 200. Bands assigned to water (1629 cm-1) were also present.The surface areas of the synthesized materials were approximately 200 g.m2 and particulates sizes around 5nm. FEG-SEM micrographs of samples obtained with and without template showed particles of different sizes, forming different clusters. Microbiological tests showed, at a concentration of 10% cerium oxide nanostructured in oxide zinc dental application, minimum inhibitory concentration value of 0,22 μg/mL-1.The results showed the influence of the template on the morphology of ceria nanoparticles, obtained by microwave-assisted hydrothermal method, its potential application as an antimicrobial agent against Streptococcus mutans bacteria, the most important microorganism related to dental caries ethiology, dental drug application.