Hydrous RuO2 has been prepared by alkaline fusion of Ru+KNO3+ KOH and successive decomposition of the ruthenate and perruthenate. The product has been analyzed by thermogravimetric analysis, differential thermal analysis, X-ray diffraction and scanning electron microscopy. Aqueous suspensions of samples of the hydrous oxide calcined at various temperatures between 300 and 500°C have been titrated potentiometrically to determine the point of zero charge. The results have been compared with commercial RuO2·xH2O. The two oxides have been found to differ in composition, structure, morphology and acid-base properties. In particular, hydrous RuO2 contains chemically bound water besides physically bound water, which is the only water present in the commercial sample. The dependence of the point of zero charge of the hydrous RuO2 on calcination temperature follows the same pattern as RuO2 obtained by thermal decomposition of RuCl3, while the behaviour of the commercial sample diverges below the temperature where the chemically bound water is lost by the hydrous RuO2. © 1989.
The point of zero charge of hydrous RuO2 / S. Ardizzone, A. Daghetti, L. Franceschi, S. Trasatti. - In: COLLOIDS AND SURFACES. - ISSN 0166-6622. - 35:1(1989), pp. 85-96. [10.1016/0166-6622(89)80321-X]
The point of zero charge of hydrous RuO2
S. Ardizzone;
1989
Abstract
Hydrous RuO2 has been prepared by alkaline fusion of Ru+KNO3+ KOH and successive decomposition of the ruthenate and perruthenate. The product has been analyzed by thermogravimetric analysis, differential thermal analysis, X-ray diffraction and scanning electron microscopy. Aqueous suspensions of samples of the hydrous oxide calcined at various temperatures between 300 and 500°C have been titrated potentiometrically to determine the point of zero charge. The results have been compared with commercial RuO2·xH2O. The two oxides have been found to differ in composition, structure, morphology and acid-base properties. In particular, hydrous RuO2 contains chemically bound water besides physically bound water, which is the only water present in the commercial sample. The dependence of the point of zero charge of the hydrous RuO2 on calcination temperature follows the same pattern as RuO2 obtained by thermal decomposition of RuCl3, while the behaviour of the commercial sample diverges below the temperature where the chemically bound water is lost by the hydrous RuO2. © 1989.
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