Platinum is one of the rarest, strongest, and most expensive elements in Earth’s crust [ref2]. At the moment, 80% of the platinum comes from South Africa [ref7]. It naturally occurs in alluvial sands, unconsolidated terrestrial sediment composed of sorted or unsorted sand, gravel, and clay that has been deposited by water [ref4]. Since it occurs naturally in the alluvial sands of various rivers, South American natives used it to produce artifacts. Platinum also occurs in form of sulfides (PtS), tellurides (PtBiTe), and arsenides (PtAs2), and as alloys with nickel or copper. Platinum arsenide, (PtAs2), is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada [ref7].
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Platinum’s resistance to wear and tarnish makes it an appropriate metal for creating fine jewelry. Also, it has an exceptional resistance to corrosion and high temperature and has stable electrical properties. All of these characteristics have been used for industrial applications [ref7]. In 2006, approximately 240 tons of platinum was sold. More than 50% of platinum was used in catalytic converters in exhaust systems of most cars. Catalytic converters combine carbon monoxide (CO) and unburned fuel with oxygen from the air, forming (CO2) and water vapor (H2O). Furthermore, 20.5% was used for making jewelry and 5.5% was used in electronics and 4.68% was used in the chemical industry as a catalyst due to its non-reactive nature. The remaining went to various other minor applications, such as electrodes and anticancer drugs [ref3].
Platinum in the form of a compound is also found to be significant to the human society. For instance, cisplatin, a platinum-containing compound, is used to treat various types of cancers because of its ability to kill cells. Cisplatin can be obtained by electrolysis of platinum electrodes [ref6]. In its pure state, platinum is quite soft. Alloying it with other platinum group metals like palladium, ruthenium and iridium can increase its hardness. For example, a combination of 950 platinum with 50 parts per thousand of ruthenium leads to the formation of a hard alloy. This alloy is preferred by the Platinum Guild and is used in wedding bands. Similarly, a combination of 900 platinum with 100 parts per thousand of iridium is an American favorite for hand fabrication of jewelry due to its added hardness [ref1].
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Although platinum has so many applications, one shouldn’t ignore the problems caused by the continued use of the element. Platinum’s excessive use in the exhaust systems of most cars causes the release of platinum compounds, which become a part of the road dust. Platinum content of road dusts can be soluble. Therefore, it enters the waters, sediments, soil and finally, the food chain [ref5]. Short-term exposure to these platinum compounds may cause irritation of the eyes, nose, and throat, and long-term exposure may cause both respiratory and skin allergies [ref7].
References:
- 1Weddingband.com. http://www.1weddingband.com/platinfo.html (accessed 12/09/02)
- Cohen, D.W. New Scientist. http://www.newscientist.com/article/mg19426051.200-earths-natural-wealth-an-audit.html (accessed 12/09/02)
- George M.W.; Platinum-Group Metals, USGS 2007, 57, 1
- Geotech.org. http://www.geotech.org/survey/geotech/dictiona.html#sectA (accessed 12/09/02)
- Ravindra, K.; Bencs, L.; Van Grieken, R. Platinum group elements in the environment and their health risk. Sci. Total Environ. 2004, 318, 1-43.
- Rosenberg, B.; Van Camp, L.; Krigas, T.; Inhibition of Cell Division in Escherichia coli by Electrolysis Products from a Platinum Electrode, Nature 1965, 205, 698-699.
- Wikipedia. http://en.wikipedia.org/wiki/Platinum (accessed 12/09/02)
