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Heterostructures based on niobates for remediation of organic contaminants


The main objective of this project deals, in this first step, with the synthesis by spray pyrolysis of K0.5Na0.5(WxNb1-x)O3-deltaNdelta, system and its heterojunction with Bi2WO6 by the hydrothermal method, resulting in the K0.5Na0.5(WxNb1-x)O3-deltaNdelta-Bi2WO6 system, where 1.0 d x d 3.0 % in mol and 0 d delta d 10 % in mass of glycine, as a source of nitrogen. Spray pyrolysis method is based on pyrolysis of an aerosol produced by ultrasonic atomizer. This method allows to obtain nanostructured powders, homogeneous in composition and in particle size, with excellent reproducibility. Hydrothermal synthesis has the advantage of using soft conditions to obtain heterostructures. Such heterostructures are built in order to improve photocatalytic efficiency and reduce the electron-hole recombination process in photocatalysis. The powders will be characterized by X-ray diffraction, with the refinement of structural parameters by Rietveld method, FTIR, Raman and UV-Visible spectroscopy, thermal analysis (TGA and DSC), zeta potential analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Nitrogen quantification in the heterostructures will be performed by CHN elemental analysis. The second step is the analysis of photocatalytic potential of the powders synthesized in the decolorization of organic contaminants. The textural analysis of the powders will be carried out by N2 adsorption using the BET method. The catalytic site will be investigated by X-ray photoelectron spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS) techniques. The photocatalytic activity of the heterostructures will be evaluated in the decolorization of organic contaminants, rhodamine 6G and bisphenol A in solution. The study of the solar fuels productions and solar-driven remediation of polluted water will be supervised by Prof. Dr. Juan Matos, of the Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, who has extensive experience in heterogeneous photocatalysis as well as reactor and photoreactors design: solar collectors; natural gas conversion and hydrogen production as alternative energy source. In this sense, it's intended to establish a cooperation with Prof. Matos with the purpose of develop methodologies for different photocatalytic reactions, as well as your collaboration in the training of graduate students of the LaCCeF group in conducting of the photocatalytic tests during the development of this research project. It is also expected to establish an official cooperation agreement between our institutions that will permit that collaborations and exchanges of training students will be a common policy. Thus, technology transfer, under this project, and studies of materials synthesized by this technique are of great importance for the clean energy production and the environmental remediation. (AU)

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(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
PRAXEDES, FABIANO R.; NOBRE, MARCOS A. L.; POON, PO S.; MATOS, JUAN; LANFREDI, SILVANIA. Nanostructured KxNa1-xNbO3 hollow spheres as potential materials for the photocatalytic treatment of polluted water. APPLIED CATALYSIS B-ENVIRONMENTAL, v. 298, . (20/00781-6, 07/03510-9, 14/11189-0)

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