Preparation and characterization of a new TiO2/SiO2 composite catalyst for photocatalytic degradation of indigo carmin

Abstract

The TiO 2 /SiO 2 composite was prepared by means of the SiO 2 -particle-entrapment method. The FTIR data showed the presence of Si-O-Ti stretching vibration band at 970 cm -1 in the TiO 2 /SiO 2 composite, suggesting a reaction between TiO 2 and silica on the TiO 2 particle surface during the silicagel formation around the TiO 2 particles. The photocatalytic efficiency of TiO 2 immobilized in silicagel was compared with that of the conventional TiO 2 Degussa P25 catalyst. For this purpose, the degradation of indigo carmin (IC) dye was used as model molecule in the tests. The effect of operational parameters such as catalyst loading and dye concentration on the photocatalytic degradation of the model dye was investigated. The rate of degradation increased with increasing catalyst loading, and when the concentration of the dye decreases.

Identification of relationship between the synthesis/process parameters and properties of a sol–gel‐derived polymer nanocomposite system

“…The FTIR spectra of the sol‐mixtures (1‐day‐aged) that contained 25 mol % Ti, and were nonrefluxed or refluxed at either 60 or 85°C were taken, and the spectral regions associated with the chemical changes thought to have taken place during the synthesis/sol ageing are shown in Figure 4. While there were no significant differences between the spectra in general, it was observable that the relative intensity of the absorption band belonging to the polymeric ether groups increased to some extent, and that of the one belonging to the epoxy rings decreased to nearly the same extent17–19 as a result of the incorporation of the reflux process applied at either 60 or 85°C. This observation indicated that the epoxy ring opening and crosslinking reactions in the refluxed systems took place to a greater extent in comparison with the nonrefluxed system.…”

“…The assignments of the generic peaks were made as follows: the broad peak around 3400 cm −1 was assigned to the OH bonds in the structure; the features around 2800 and 3000 cm −1 were assigned to the CH bonds; the strong peak around 1000 cm −1 was assigned to the SiOSi species. In addition, the peak around 910 cm −1 was assigned to the epoxy rings in the structure,16 and that around 950 cm −1 to the SiOTi species 17. The presence of the latter in the samples containing Ti demonstrated that Ti did incorporate into the final structure of the materials.…”

Light‐curing of a sol–gel‐derived silicate‐based epoxy‐functional polymer nanocomposite material system

“…The assignments of the generic peaks were made as follows: the broad peak around 3,400 cm −1 was assigned to the OH bonds in the structure; the features around 2,800 and 3,000 cm −1 were assigned to the CH bonds; the strong peak around 1,000 cm −1 was assigned to the SiOSi species. In addition, the peak around 910 cm −1 was assigned to the epoxy rings in the structure , and that around 950 cm −1 to the SiOTi species . The presence of the latter in the samples containing Ti demonstrated that Ti did incorporate into the final structure of the materials.…”

Oxidative desulfurization of thiophene on TiO2/ZSM-12 zeolite

“…Two bands were displayed in the spectra: the 3419 cm -1 one, related to the stretching of OH bonds, and the 1644 cm -1 band, related to the deformation of the OH bonds 13 . FTIR spectra of the TiO 2 /ZSM-12 samples showed an enlargement in two specific bands, 1097 and 803 cm -1 in relation of the ZSM-12 calcinated, which may be related to the presence of vibrations by Si-O-Si stretching and between these two bands, Ti-O-Si vibrations, as confirming the presence of titanium oxides in the samples 14 . The oxidative desulfurization reactions were performed in order to obtain the conversion of thiophene to sulfone as function of the reaction time present in a n-heptane solution at a concentration of 5000 ppm, and also in order to analyze the catalytic potential of the supported catalysts with different titanium content (5, 10 and 15%).…”