Rear wheels of a truck sitting on tarmac

Rubber tyres shed a toxic chemical, but with the help of heat and acid this can be converted into materials with applications in electronics. Credit: Andre Kudyusov/Getty

Chemistry

Toxic tyre waste turned into electronic treasure

By-product of rubber tyres is transformed into valuable organic semiconductors.

When the rubber meets the road, it invariably leaves behind traces of the chemicals used to harden it during tyre manufacture. These chemicals, notably 2-(methylthio)-bezothiazole (MTBT), wash into waterways, where they can pose a health hazard if left untreated. The reactions used to break down MTBT just leave behind more waste — benign but useless.

Researchers in China report that they have found a way to not only neutralize MTBT, but also turn it into something valuable: an organic semiconductor. These are cheaper and more flexible than metallic semiconductors, and can be incorporated into items such as mobile-phone displays. Hui Huang at the University of the Chinese Academy of Sciences in Beijing and his colleagues applied a method that relies on a metal catalyst, acid and heat.

The team experimented with different recipes and temperatures to turn the MTBT into several different semiconductor compounds. One could be used to build a field-effect transistor, a key component of electronic devices. From another, the researchers created semiconductor nanoparticles, which can act as fluorescent dyes that allow scientists to image living cells in action.