Sol-Gel Preparation, Characterization and Photocatalytic Activity of Nanostructured TiO 2 Nanoparticles
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Sol-Gel Preparation, Characterization and Photocatalytic Activity of Nanostructured TiO2 Nanoparticles R. Carrera1*, S. Castillo2 1
Sección de Estudios de Posgrado e Investigación, Instituto Politécnico Nacional, 07738 D.F. México 2
Programa de Ingeniería Molecular, Instituto Mexicano del Petróleo, 07738 D.F., México
Email: [email protected]
ABSTRACT To establish a promising method for the purification of air containing volatile organic compounds, TiO2 nanoparticles with interesting physicochemical properties were prepared by the sol-gel method to perform the photocatalytic decomposition of acetaldehyde. The obtained samples were characterized by the x-ray diffraction -Rietveld refinement, transmission electron microscopy (TEM) and the Brunauer, Emmet and Teller (BET) model. According to the results, the sample that presented the highest activity (96.4%) in the photocatalytic oxidation of acetaldehyde was the one annealed at 200 0C. This material showed the presence of a mixture of the anatase (higher proportion) and brookite phases, nanometric crystal size (7.03 nm) and high surface area (189 m2g-1). The physicochemical properties present in the TiO2-P-200°C nanoparticles suggest that they may establish a photoassisted reaction process for air purification, in which volatile organic compounds are photocatalitically decomposed. Keywords: Ti, sol-gel, crystal, x-ray diffraction (XRD), transmission electron microscopy (TEM). INTRODUCTION Recently, as a result of the search and development of new materials, TiO2 nanoparticles have been considered as very interesting materials due to their applications in air pollution control [1]. In this field, TiO2 nanoparticles play a major role since one of the most important targets in the control of volatile organic compounds (VOCs) is the decomposition of low concentrations of formaldehyde and acetaldehyde in indoor environments through photoassisted reactions. These contaminants are emitted from buildings, interior materials and newly built houses that have damaged our health through the so-called sick-house syndrome [2]. Acetaldehyde is produced by the oxidation of volatile organic compounds when they are in contact with ozone in carpets, furniture, etc., and it is one of the most toxic VOCs [3]. The synthesis of nanostructured materials such as TiO2 nanoparticles by wet chemistry routes is a powerful way to obtain reproducible homogeneous samples. The control of the crystal size and phase composition ratio obtained by the sol-gel method is, by far, one of the most versatile, reproducible procedures in comparison with other methods, mainly to obtain high reactivity, crystal size and high surface areas [4, 5].
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From the three TiO2 phases (anatase, rutile and brookite), only the mixture of the two first phases has been widely studied, evaluated and compared in diverse photocatalytic applications, since the brookite phase occurs in small quantities as a by-product depending on the specific experimental conditions [6, 7]. The aim of the present research work was to synthesi
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