Open AccessUSE OF SiO2/TiO2NANOSTRUCTURED COMPOSITES IN TEXTILE DYES AND THEIR PHOTODEGRADATION IN RESPONSE TO NATURAL SUNLIGHT
Author(s) -
Camila S. Inagaki,
Andrea Eloisa da Silva Reis,
Nayara Maria Silvério da Costa Dallefi Oliveira,
Vitor H. Paschoal,
Ítalo Odone Mazali,
Antônio A. S. Alfaya
Publication year - 2015
Publication title -
química nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.214
H-Index - 73
eISSN - 1678-7064
pISSN - 0100-4042
DOI - 10.5935/0100-4042.20150105
Subject(s) - photodegradation , textile , materials science , sunlight , composite material , photocatalysis , catalysis , chemistry , optics , organic chemistry , physics
SiO2/TiO2 nanostructured composites with three different ratios of Si:Ti were prepared using the sol-gel method. These materials were characterized using energy dispersive X-ray fluorescence, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, photoluminescence, Raman with Fourier transform infrared spectroscopy, and the specific surface area. The band gaps of materials were determined by diffuse reflectance spectra, and the values of 3.20 ± 0.01, 2.92 ± 0.02, and 2.85 ± 0.01 eV were obtained as a result of the proportional increases in the amount of Ti within the composite. The materials exhibit only the anatase (TiO2) crystalline phase and have crystalline domains ranging from 4 to 5 nm. The photodegradation process of methylene blue, royal blue GRL, and golden yellow GL dyes were studied with respect to their contact times, pH variations within the solution, and the variations in the dye concentration of the solution in response to only sunlight. The maximum amount of time for the mineralization of dyes was 90 min. The kinetics of the process follows an apparently first order model, in which the obtained rate constant values were 5.72 × 10-2 min-1 for methylene blue, 6.44 × 10-2min-1 for royal blue GRL, and 1.07 × 10-1min-1 for golden yellow