Study on preparation and properties of kaolin/ZrO₂ nanopowders

The ZrO₂ and kaolin/ZrO₂ nanopowders were prepared by hydrothermal method, using Zr(NO₃)₄·5H₂O as the zirconium source. The properties and microstructures of the obtained powders were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), ultraviolet and visible spectrophotometry (UV-Vis), and Brunauer-Emmet-Teller (BET) nitrogen adsorption method. In the results, both ZrO₂ and kaolin/ZrO₂ samples show the nanoscale microspheres with the mesoporous structure, and the surface microspheres of kaolin/ZrO₂ after calcination at 400℃ are more uniform without agglomeration; the ZrO₂ mainly exists in amorphous form, but a small number of tetragonal ZrO₂ phases are present in these two samples. The absorbance of kaolin/ZrO₂ nanopowders is stronger than that of pure ZrO₂ in the wavelength ranging from 190 to 800 nm, and the BET specific surface area is 19.05 m²·g^-1 higher than that of pure ZrO₂. The results indicate that the kaolin/ZrO₂ nanopowders have the greater advantages and potential in the preparation of ultraviolet specific materials and photo-catalytic treatment industrial wastewater.