Photooxidation of dichloroacetic acid controlled by pH-stat technique using TiO 2 /layer silicate nanocomposites

Photooxidation of dichloroacetic acid controlled by pH-stat technique using TiO 2 /layer silicate... Nanocomposites containing anatase nanoparticles were prepared by heterocoagulation, using Na-montmorillonite and titanium dioxide obtained by hydrothermal sol–gel method. Heterocoagulation was carried out at pH 1 and 4. Based on X-ray diffraction measurements, an average particle size of 3.8–4.0 nm was calculated by the Scherrer equation for the particles intercalated between the silicate lamellae. Nitrogen adsorption studies revealed that the specific surface area of nanocomposites prepared at pH 1 varies in the range of 157–284 m 2 /g, depending on the TiO 2 content. After preparation at pH 4, the specific surface area of the samples is lower (123–248 m 2 /g). UV–vis analyses of the nanocomposites showed that as TiO 2 content is increased, band gap energies relative to TiO 2 decrease and gradually approach the value obtained for the pure sol–gel TiO 2 sample ( E g = 3.12 eV). The nanocomposites obtained were tested in photocatalytic degradation of dichloroacetic acid (DCA) in a suspension photoreactor. The reaction was quantitatively monitored during the entire irradiation time using the pH-stat technique. We found that higher catalytic efficiencies could be achieved when increasing sample TiO 2 content. The photocatalytic efficiency of composites prepared at pH 1 was well below that of the samples prepared at pH 4, which was attributed to structural changes in the support brought about by the highly acidic medium. When photocatalytic degradation data were normalized to pure TiO 2 , composite samples containing 47% and 57% TiO 2 were found to be the most efficient as compared to the 100% TiO 2 sample prepared by the sol–gel method. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied Catalysis B: Environmental Elsevier

Photooxidation of dichloroacetic acid controlled by pH-stat technique using TiO 2 /layer silicate nanocomposites

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Publisher
Elsevier
Copyright
Copyright © 2006 Elsevier B.V.
ISSN
0926-3373
D.O.I.
10.1016/j.apcatb.2006.07.012
Publisher site
See Article on Publisher Site

Abstract

Nanocomposites containing anatase nanoparticles were prepared by heterocoagulation, using Na-montmorillonite and titanium dioxide obtained by hydrothermal sol–gel method. Heterocoagulation was carried out at pH 1 and 4. Based on X-ray diffraction measurements, an average particle size of 3.8–4.0 nm was calculated by the Scherrer equation for the particles intercalated between the silicate lamellae. Nitrogen adsorption studies revealed that the specific surface area of nanocomposites prepared at pH 1 varies in the range of 157–284 m 2 /g, depending on the TiO 2 content. After preparation at pH 4, the specific surface area of the samples is lower (123–248 m 2 /g). UV–vis analyses of the nanocomposites showed that as TiO 2 content is increased, band gap energies relative to TiO 2 decrease and gradually approach the value obtained for the pure sol–gel TiO 2 sample ( E g = 3.12 eV). The nanocomposites obtained were tested in photocatalytic degradation of dichloroacetic acid (DCA) in a suspension photoreactor. The reaction was quantitatively monitored during the entire irradiation time using the pH-stat technique. We found that higher catalytic efficiencies could be achieved when increasing sample TiO 2 content. The photocatalytic efficiency of composites prepared at pH 1 was well below that of the samples prepared at pH 4, which was attributed to structural changes in the support brought about by the highly acidic medium. When photocatalytic degradation data were normalized to pure TiO 2 , composite samples containing 47% and 57% TiO 2 were found to be the most efficient as compared to the 100% TiO 2 sample prepared by the sol–gel method.

Journal

Applied Catalysis B: Environmental – Elsevier

Published: Oct 26, 2006

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