Electrochemical dissolution of platinum in an ionic liquid

January 12, 2012

(PhysOrg.com) -- Precious metals, especially platinum, are important catalytic materials for many chemical reactions. For example, platinum is used in some fuel cells; however, broad commercialization of such fuel-cell technology is hampered by the fact that platinum is rare and thus far too expensive. Growing demand is making it necessary to develop efficient and environmentally friendly processes for recycling platinum. Jing-Fang Huang and Hao-Yuan Chen at the National Chung Hsing University in Taiwan have now introduced a new approach in the journal Angewandte Chemie. Their method is based on the dissolution of the metal in an ionic liquid.

Recycling is a difficult, complicated process. The first step is the dissolution of the used platinum. Because platinum is a very special precious metal, this isn’t so easy. The solvents used for this are usually highly corrosive aqua regia, a mixture of nitric and hydrochloric acids, or a highly oxidizing mixture of sulfuric acid and hydrogen peroxide known as piranha. There are also electrochemical recycling processes, but these mostly require highly toxic electrolytes or corrosive media, or they release toxic gases. They also suffer from insufficient current densities and passivation of the electrodes.

Huang and Chen have now developed a novel process that avoids all of these disadvantages. In this procedure, platinum is electrochemically dissolved in a mixture of zinc chloride and a special ionic liquid. An ionic liquid is an organic salt that is in a melted state at temperatures below 100 °C. Ionic liquids are considered environmentally friendly solvents because they have very low vapor pressures and are very thermally stable, so they do not release any toxic substances. They also have high ionic conductivity, which makes them very useful in electrochemical applications.

The used platinum is introduced in the form of an electrode, a voltage is applied, and the surrounding ionic liquid heated to about 100 °C. The platinum then dissolves surprisingly fast. The dissolved platinum can then be removed on a carrier electrode, either as the pure metal or as a zinc alloy, without prior treatment of the solution. The scientists are optimistic that this process can also be adapted for other .

Says Huang: “We are doing our best to solve the problem about the effective use of precious metals. The recycling of precious metals is a possible strategy. Even now, we do not think we have found the best process. We will continuously modify the process in order to extend its applications or look for a much better one”.

Explore further: Today's waste, tomorrow's fuel

More information: Angewandte Chemie International Edition, DOI: 10.1002/anie.201107997

Related Stories

Today's waste, tomorrow's fuel

July 3, 2007

A Cardiff University research collaboration is working to recycle precious metals from road dusts and vehicle exhausts to create greener energy.

Scientists demonstrate novel ionic liquid batteries

April 15, 2011

(PhysOrg.com) -- Scientists at the NRL Materials Science and Technology Division are providing solid evidence that there is a new route towards developing novel, lightweight energy storage devices. By moving away from centuries ...

Environmentally friendly rockets

May 27, 2011

(PhysOrg.com) -- Many rockets, satellites, and spacecraft are driven by hydrazine, sometimes with an oxidizing agent like nitric acid or dinitrogen tetroxide. When filling tanks with these highly toxic substances, technicians ...

Recommended for you

A new form of real gold, almost as light as air

November 25, 2015

Researchers at ETH Zurich have created a new type of foam made of real gold. It is the lightest form ever produced of the precious metal: a thousand times lighter than its conventional form and yet it is nearly impossible ...

Moonlighting molecules: Finding new uses for old enzymes

November 27, 2015

A collaboration between the University of Cambridge and MedImmune, the global biologics research and development arm of AstraZeneca, has led researchers to identify a potentially significant new application for a well-known ...

Atom-sized craters make a catalyst much more active

November 24, 2015

Bombarding and stretching an important industrial catalyst opens up tiny holes on its surface where atoms can attach and react, greatly increasing its activity as a promoter of chemical reactions, according to a study by ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.