ISSN 0004-881X

SOL-GEL SYNTHESIS OF TUNNEL STRUCTURE MATERIALS AND THEIR PHOTOCATALYTIC PERFORMANCE ON REDOX REACTIONS IN AQUEOUS SOLUTIONS

by Leticia M. Torres-Martinez*, Lorena L. Garza-Tovar, Isaias Juarez-Ramirez, and Arquimedes Cruz Lopez
Departamento de Ecomateriales y Energia, Instituto de Ingenieria Civil, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Av. Fidel Velasquez y Av. Universidad, Cd. Universitaria
San Nicolas de los Garza Nuevo Leon, CP 66450 Mexico

Abstract

In this work we present the photocatalytic activity of new ceramic semiconductors, with rectangular tunnel structures which are isostructural to Na2Ti6O13. These alkaline titanates were studied using the reduction-oxidation reaction of Cr+6 from aqueous solutions at room temperature. The synthesis of these compounds as pure phases was achieved by sol-gel method using metallic alcoxides at pH 7. The fresh gels were heat treated at 200, 400, 600 and 800°C. Reaction products were characterized by XRD, FTIR, N2 Physisorption and DTA-TGA techniques. The band gap energy (Eg) of each sample prepared was calculated from UV-Vis spectra. The Eg values obtained ranged from 3.4 to 3.1. The best activity found for Cr+6, reduction after 3.5 hours under UV radiation was performed by Na1.8Ba0.3Ti5.9O13 sol-gel pH 7, treated at 800°C. Kinetic studies showed half life values of t1/2 = 59 min. We consider that the photocatalytic activity is favored when the structure was already formed.

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