Investigation into the solubility of nanopowders of the ZrO2–Y2O3–CeO2–Al2O3 system in the aqueous medium at various pH

Abstract

Nanopowders of ZrO₂–Y₂O₃–CeO₂ and ZrO₂–Y₂O₃–CeO₂–Al₂O₃ systems are investigated with the purpose of studying the influence of pH of the dispersed medium on the solubility of nanopowder particles of a complex composition in an aqueous medium after membrane filtration and centrifugation to further prepare the stable dispersions necessary for toxicological investigations of nanoparticles. Concentrations of elements remaining in a supernatant after the sample preparation, which includes membrane filtration and centrifugation, are measured by inductively coupled plasma optical emission spectroscopy. It is established that that the largest aggregative stability of the nanopowder dispersion without the Al₂O₃ additive corresponds to the optimal range of pH 5.5–9.5, while with the Al₂O₃ additive, it is region pH 7.0. The results evidence that, when dispersing these powders, the hydrosol of yttrium oxyhydroxide, which is dissolved at pH < 6.0, is formed. When dissolving in water of the powder with the Al₂O₃ additive in the neutral medium, aluminum hydroxide is formed; in the acidic medium (pH < 6), it is replaced by main soluble aluminum salts; and in the alkali medium (pH > 7), amphoteric aluminum hydroxide is dissolved because of the formation of aluminates.