Sol–gel synthesis of sodium silicate and titanium oxychloride based TiO2–SiO2 aerogels and their photocatalytic property under UV irradiation
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Date
2013-07-26
Journal Title
Journal ISSN
Volume Title
Publisher
Chemical Engineering Journal
Abstract
Binary titania–silica metal oxides (TiO2–SiO2) have preferentially been used as photocatalysts for the degradation
of organic contaminants under UV irradiation. Herein we synthesized TiO2–SiO2 aerogel powders
with different Si-to-Ti ratios suitable for decolorization of organic pollutants using less expensive
silica source (sodium silicate) and titanium oxychloride as a titania precursor. Consequently, the surfaces
of the alcogels were hydrophobized using trimethylchlorosilane (TMCS) as a silylating agent to yield
hydrophobic aerogel powders at ambient pressure drying. The as-prepared samples were calcined at different
temperatures ranging from 200 to 1000 C to evaluate the effect of the heat treatment in the
microstructure of the aerogels. The physico-chemical properties of the aerogels were examined by
XRD, FTIR, XRF, TEM, SEM, N2 gas physisorption studies, TGA/DTA and diffusive reflectance spectrometry
analyses. It was found that calcination temperature is an important factor in improving the porosity and
crystallinity of the aerogels however; it has a detrimental effect on the hydrophobicity and photochemical
performance of the aerogels. The as-synthesized aerogels were hydrophobic and exhibited the highest
activity toward decolorization of methylene blue. The hydrophilic aerogels were obtained after
calcination at temperature P500 C however; the formed samples possessed lower activities. Hydroxyl
radicals ( OH) detection experiment performed in the presence of the photocatalysts indicated that the
generation of radicals during irradiation increases with increasing illumination time.
Description
Keywords
TiO2-SiO2 aerogel, sol-gel process, TiOCl2, Ambient pressure drying, Sodium silicate, Photocatalysis