Effect of Kaolinite Exfoliation on the Photocatalytic Properties of Kaolinite/Ti02 Composite

摘要

Photocatalytically active composites based on the nanostructured TiO_2 fixed on the surface of raw and exfoliated kaolinite were prepared. Exfoliation of the kaolinite was achieved after the thermal treatment of the kaolinite previously intercalated with urea. It was observed that the introduction of urea into kaolinite interlayer significantly increases the dehydroxylation rate even at the relatively low temperature 500 °C. The exfoliation of kaolinite led to increasing of specific surface area from 14.3 m~2/g measured for original kaolinite to 24.3 m~2/g obtained for exfoliated kaolinite. Kaolinite/TiO_2 composites with 50 wt.% of TiO_2 were prepared using thermal hydrolysis of titanyl sulphate. Prepared composites were further thermally treated at 500 °C and characterized using X-ray fluorescence spectroscopy and X-ray diffraction method. It was observed that higher yield of Ti02 was achieved for the composites prepared using exfoliated kaolinite and it was proved that TiO_2 occurs in anatase form. The photodegradation activity of the prepared composites was proved using UV induced discoloration of their aqueous suspension containing azo dye acid orange 7. Comparing the photodegradation activity of the composites there was not detected any significant difference related between the samples prepared using original and exfoliated kaolinite.