title: Characterization and dissolution properties of ruthenium oxides.
abstract: Ruthenium oxides (RuO(2)·1·10H(2)O and RuO(2)) have been synthesized by forced hydrolysis and oxidation of ruthenium chloride. The resulting materials were extensively characterized to determine the crystallinity, surface area, and ruthenium oxidation state. Surface charging experiments indicate a large quantity of reactive functional groups for both materials and a decrease in the acidity of the surface functional groups with crystallization of the hydrous oxide. Dissolution studies conducted in acidic and basic pH environments indicate Ru-oxides are insoluble in 0.1 M HCl and slightly soluble in 0.1 M NaOH. Oxalate and ascorbate (5 mM) promoted dissolution of RuO(2)·1·10H(2)O demonstrated an increase in dissolution rates with decreasing pH and increasing ligand surface coverage. XPS analysis of the RuO(2)·1·10H(2)O surface after ligand promoted dissolution revealed the reduction of Ru(IV) to Ru(III) indicating that both ascorbate and oxalate reductively dissolve RuO(2)·1·10H(2)O. Dissolution experiments with RuO(2) resulted in dissolution only for 5 mM oxalate at pH 3. Dissolution rates calculated for RuO(2)·1·10H(2)O and RuO(2) are compared with previously published dissolution rates for iron oxides, demonstrating an order of magnitude decrease in the oxalate and ascorbate promoted dissolution.
authors.affiliation: Virginia Polytechnic Institute and State University, College of Agriculture and Life Sciences, Blacksburg, VA 24061, USA. luxton.todd@epa.gov
authors.forename: Todd P
authors.initials: TP
authors.lastname: Luxton
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Eick
authors.forename: Kirk G
authors.initials: KG
authors.lastname: Scheckel
mesh_terms: D006863:Hydrogen-Ion Concentration; D010316:Particle Size; D017975:Ruthenium Compounds / Q000737:chemistry*; D012995:Solubility; D013499:Surface Properties
chemical_list: D017975:Ruthenium Compounds; C029017:ruthenium dioxide