What Is Ruthenium?
Ruthenium is a silvery-white, hard but brittle solid that easily transforms into powder. This element belongs to the platinum group, with the symbol Ru, atomic number 44, atomic weight 101.07, and CAS number 7440-18-8. Discovered by the German chemist Osan in 1828 from deposits in the Urals of Russia, its first pure isolation was achieved by the Russian chemist Krauss in 1844. Ruthenium naturally occurs in the earth’s crust alongside other platinum metals like iridium.
Uses of Ruthenium
Ruthenium’s applications are diverse, spanning various fields:
1. Addition to Metals
Alloyed with platinum, palladium, titanium, and molybdenum, ruthenium enhances resistance to corrosion, oxidation, and wear. Ruthenium-palladium alloys find use in jewelry, ornaments, and dentistry, while ruthenium-platinum alloys serve in electrical contacts and decorations.
2. Medical Materials
The beta-decay isotope Ru-106 is utilized in radiotherapy for ocular tumors, especially malignant melanoma of the uvea. Ruthenium complexes are being explored for their potential anti-cancer properties, offering greater hydrolysis resistance and expected tumor selectivity compared to platinum complexes.
3. Catalysts
Ruthenium compounds are valuable as catalysts in various chemical reactions. Homogeneous catalyst applications include olefin metathesis, catalyzed by ruthenium trichloride and Grubbs catalysts, and enantioselective hydrogenation of ketones. Heterogeneous catalyst uses involve Fischer-Tropsch synthesis.
4. Others
Additional uses of ruthenium include cathodic protection of structures and as components of composite metal oxide anodes in chlorine production from salt water via electrolysis.
Properties of Ruthenium
With a melting point of 2,450°C and a boiling point of 3,700°C, Ruthenium is a solid at room temperature, featuring a density of 12.43 g/cm3. It shows remarkable chemical stability, being insoluble in acids, including aqua regia, and only soluble in molten alkalis, forming ruthenates (RuO42-). Ruthenium significantly enhances hardness and strength when alloyed in small quantities with platinum, palladium, or titanium.
Other Information on Ruthenium
1. Ruthenium Manufacturing Process
Ruthenium is obtained commercially as a by-product from nickel, copper, and platinum ore processing. During the electrolytic refining of copper and nickel, it precipitates as anodic mud along with other precious metals, from which ruthenium can be extracted. It is also sourced from spent nuclear fuel as a fission or neutron absorption product.
2. Ruthenium Reactions
Ruthenium can be oxidized to ruthenium dioxide (RuO2) and further to ruthenium tetroxide (RuO4), a potent oxidant, using sodium meta-periodate. Ruthenium tetroxide serves mainly as an intermediate in ruthenium purification from ores and radioactive waste.
3. Regulatory Information
Ruthenium is not regulated under any safety laws.
4. Handling and Storage Precautions
Recommended precautions for handling and storage include sealing the container tightly, storing it in a dry, cool, and dark place, using it in well-ventilated areas or outdoors, avoiding contact with strong oxidizers, and wearing protective gear. After handling, thorough hand washing is advised, along with immediate rinsing of skin or eyes upon contact.