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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 |
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