Thursday, April 23, 2009

Osmium, Osmium, Everywhere

I don’t use osmium much. In fact, I don’t think I’ve ever used an osmium compound, although I’m fairly certain I once picked up a bottle of OsO4. The sum total of my osmium knowledge consists of knowing OsO4 (osmium tetroxide) is quite toxic. However, it now appears that if I ever do have need of osmium, I can just go outside and grab some. A group of researchers has studied the distribution of osmium across the globe and found that a surprising amount of the element is now present in rain, in snow, and in our rivers.

Osmium naturally occurs along with copper and nickel and is a by-product of their manufacture. But all this osmium in our water system comes from another source – during the production of platinum – much of which is used for the manufacture of automotive exhaust catalysts. During the process of refining platinum, the ore is subjected to high temperatures to burn out sulfur impurities. But volatile OsO4 is also produced and it has been spreading. According to the researchers, the levels of osmium are still small enough that this may not be a health concern, at least so far….

Russia and South Africa produce over 90% of the world’s supply of platinum and neither country regulates these osmium emissions. The demand for platinum may have dropped temporarily due to the worldwide plunge in car and truck sales, but it will return eventually. In addition, the current generation of hydrogen fuel cells also depend upon platinum for their electrodes, which means the rate of osmium release will probably only increase in the future.

Since I did mention platinum, I’ll point out that this week’s Chemistry In Its Element podcast covers platinum and its chemistry. Podcasts for many other elements are also available, including osmium, so feel free to see if your favorite element has been discussed yet.

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