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Microemulsion-Mediated Synthesis of Nanosize Oxide Materials
Published in Promod Kumar, K. L. Mittal, Handbook of Microemulsion Science and Technology, 2018
Wang et al. [107] synthesized zirconium hydroxide particles with the two-micro-emulsion method. The microemulsion system adopted was NP-5/NP-9/cyclohexane/water, and a Zr-containing microemulsion was mixed with an NH3-containing microemulsion (path AP3, Fig. 1). The as-produced zirconium hydroxide particles were spherical, and particle size was in the 5–40 nm range, as determined by TEM. The extracted particles, dried at 100°C, were X-ray amorphous. Thermogravimetric analysis (TGA) revealed two main weight loss steps, i.e., from room temperature to 120°C and from 120°C to 410°C. The first weight loss was attributed to the removal of residual water and solvent, while the second and more drastic weight loss was assigned to the transformation of zirconium hydroxide to zirconia, with additional contributions from solvent and surfactant removal. Differential thermal analysis (DTA) of the particles gave a major exotherm at 362°C, followed by a minor peak at 453°C. On the basis of X-ray diffraction data, the 362°C exotherm was attributed to the hydroxide-to-oxide transformation, while the 453°C exotherm was attributed to secondary crystallization. The primary crystallization temperature of 362°C was about 100°C lower than the corresponding temperature for conventional bulk aqueous phase synthesis.
Improving dispersion stability of zirconium hydroxide sol for preparing nano zirconia by the reverse precipitation
Published in Journal of Dispersion Science and Technology, 2019
Song-Ho Ri, Se-Ok Pak, Hye-Song Kwak, Yongsaeng Ri, Song-Jin Im
Zirconium hydroxide sol was prepared by the reverse precipitation method with ZrOCl2 solution as raw material and processing condition of the zirconium hydroxide sol was investigated. The pH-range for the stable zirconium hydroxide sol has been determined by measuring the zeta potential change of the zirconium hydroxide sol at different pH values. The effect of the surfactant PEG600 on the zirconium hydroxide sol particle has been discussed. The saturated absorption amount of the surfactant is 1.0 wt% the pH value for the highest stability was shifted from 7.9 to 9.3 and the pH range for preparing stable zirconium hydroxide sol widened as 8.0–11.0. The suitable concentration of the ZrOCl2 solution for the efficient gelation keeping the high dispersion stability has been investigated. On the basis of discussion of drying way of the prepared wet gel of zirconium hydroxide, the microwave drying has been demonstrated to be suitable for preparation of nanoparticle. The thermolysis process of zirconium hydroxide gel has been discussed. When the zirconium hydroxide gel was heated at 600 °C for 2h, tetragonal nanozirconia, of which particle size was around 35 nm, was prepared.