Heterogeneous equilibria in the Ru-H2O, Ru-Cl-H2O and Ru-S-H2O systems

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Logarithmic activity-activity diagrams, including Eh-pH, log{M}-pH and log{ligand}-pH diagrams have been generated with the aid of the DIAGRAM computer program for the systems Ru-H2O, Ru-Cl-H2O and Ru-S-H2O at 25 °C. Analysis of these diagrams indicates that elemental ruthenium exhibits a large stability field in aqueous solution, dissolving to Ru(III) and Ru(IV) species in acidic solutions only at relatively high oxidation potentials. Anhydrous RuO2 spans most of the pH range in aqueous solution so it is relatively stable in both acidic and alkaline solutions. Hydrated amorphous RuO2 is less stable than the anhydrous dioxide. A series of chloro or mixed hydroxo-chloro complexes form in the presence of chloride ions and their stability domains depend on both the Cl- ion concentration and the oxidation potential. The sulfide RuS2 is also stable in aqueous solution. The implications of these diagrams for dissolution and precipitation processes are discussed.

Original languageEnglish (US)
Pages (from-to)103-114
Number of pages12
JournalJournal of The Less-Common Metals
Issue number1
StatePublished - Jun 1989

All Science Journal Classification (ASJC) codes

  • Engineering(all)


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