We report on a new approach for the synthesis of TiO2-pillared montmorillonite, where the pillars exhibit a high degree of crystallinity (nanocrystals) representing a mixture of anatase and rutile phases. The structures exhibit improved adsorption and photocatalytic activity as a result of hydrothermally activated intercalation of titanium polyhydroxo complexes (i.e., TiCl4 hydrolysis products) in a solution with a concentration close to the sol formation limit. The materials, produced at various annealing temperatures from the intercalated samples, were characterized by infrared spectroscopy, differential scanning calorimetry (DSC)/thermogravimetric analysis (TGA), X-ray diffraction, dynamic light scattering (DLS) measurements, and liquefied nitrogen adsorption/desorption. The photocatalytic activity of the TiO2-pillared materials was studied using the degradation of anionic (methyl orange, MO) and cationic (rhodamine B, RhB) dyes in water under UV irradiation. The combined effect of adsorption and photocatalysis resulted in removal of 100% MO and 97.5% RhB (with an initial concentration of 40 mg/L and a photocatalyst-sorbent concentration of 1 g/L) in about 100 minutes. The produced TiO2-pillared montmorillonite showed increased photocatalytic activity as compared to the commercially available photocatalyst Degussa P25.
An
ultrasound-assisted biotemplate method for producing biomorphic
fibrous titanium oxide (TiO2) is reported. Wood pulp in
the form of sheets was used as a biotemplate, and a solution of titanium
hydroxocomplexes as a precursor. On completing the impregnation, the
samples were dried and calcined at temperatures of 300–1000
°C. The process of obtaining fibrous TiO2, as well
as its structure and textural properties, was investigated by DSC/TG
analysis, X-ray diffraction, scanning electron microscopy, and nitrogen
adsorption/desorption, while photocatalytic activity was studied using
Rhodamine B dye degradation by UV irradiation. It is shown that the
phase composition, textural and sorption characteristics of the biomorphic
TiO2 samples essentially depend on the biotemplate annealing
temperature. The TiO2 sample obtained at 600 °C is
a mixture of anatase and rutile (with a ratio of 72 and 28%, respectively)
and possesses the highest surface area, adsorption capacity, and photocatalytic
activity with respect to Rhodamine B. All samples of biomorphic TiO2 are characterized by increased photocatalytic activity as
compared to commercially available photocatalyst Degussa P25.
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