The influence of chemical and thermal treatment on the point of zero charge of hydrous zirconium oxide

Abstract

Two zirconia samples were prepared by precipitation from aqueous zirconium oxychloride and zirconil sulphate solutions with potassium hydroxide. The prepared zirconia samples were amorphous. The pHpzc values of zirconia samples, determined from NaCl and NaNO3 solutions, were 6.6 ± 0.1 and 6.9 ± 0.1, respectively. After prolonged hydration of zirconia in doubly distilled water, pHpzc decreased to 4.7 ± 0.3. Crystallization into tetragonal (metastable) + monoclinic zirconia appeared at 691 K. Above 873 K, tetragonal metastable phase changes to monoclinic one. It was shown that crystallite sizes of zirconia treated at 673 - 1273 K increased from 9.5 nm to 40.5 nm, respectively. The increase in temperature from 385 K to 1070 K increased the pHpzc of zirconia samples from 6.6 to 9.0, respectively. [Projekat Ministarstva nauke Republike Srbije, br. 45012]

Keywords

• zirconium oxide
• point of zero charge
• thermal analysis
• surface properties