Preparation and UV-shielding property of Zr0.7Ce0.3O2-kaolinite nanocomposites

Nanocomposites of Zr0.7Ce0.3O2-kaolinite were prepared by two different methods. The first method was by solid mixing of kaolinite and Zr0.7Ce0.3O2 (ZrCeO), the latter being prepared by a citric acid complexion method, using an agate pestle and mortar as the mixing medium. The second method was by adding kaolinite during the synthesis of Zr0.7Ce0.3O2 (ZrCeO) itself. Kaolinite was obtained by the elutriation of tin tailing, which was then exfoliated by planetary ball milling with 40 mass% of urea for 1-5 h. The resulting nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), and specific surface area (SSA) determination using the BET (Brunauer-Emmett-Teller) method. The characterization results proved that kaolinite was successfully exfoliated by urea treatment after 5 h. It was also found that ZrCeO-exfoliated kaolinite nanocomposite, synthesized by the citric acid complexion method, without adding NH3, showed the highest UV-shielding property of > 80% absorption ability for wavelength < 400 nm. This is better than pure ZrCeO, even at the lower content of ZrCeO in the nanocomposite (i.e. at 70 mass% content).