Degrading asbestos out of the environment

The presence of asbestos as a persistent pollutant in soil and water is of major environmental concern, but scientists at the University of Torino, Italy, may have found a way to clean it up.

Despite many countries having imposed strict regulations that limit asbestos use and control asbestos disposal, asbestos is still a growing environmental problem. For example, the various types of silicates that are classed as asbestos are often found in water or mud surrounding disused asbestos mines.

There are standard procedures for removing asbestos from buildings, but these aren’t suitable for application to soil or water remediation. Now, Bice Fubini and colleagues have developed a new procedure that could be developed into a tool for bioremediation of asbestos contaminated environments.

The researchers managed to degrade chrysolite – the most common form of asbestos – using a combination of oxalic acid and ultrasound treatment.  Oxalic acid acts as a chelating agent, binding to the magnesium in the asbestos. Together with the ultrasound, this disrupts the mineral structure, breaking down the long fibres that make the asbestos species carcinogenic. The resulting product is mainly an amorphous solid, with small amounts of mineral fibres that are unregulated and believed to be harmless.

Mike Hochella, professor of mineralogy and geochemistry at Virginia Polytechnic Institute and State University (or Virginia Tech), US, was impressed with the results. ‘The Fubini group has long been recognized as one of the best labs in the world for the study of fibrous silicates, and they have had many breakthrough discoveries. This paper appears to be another breakthrough,’ he said. ‘In the earth, these fibres may persist for as long as millions of years. In an organism, they may persist from years to decades. Under the treatment described in this paper, they persist for less than 24 hours. This technique has great potential as a remediation tool, and it may be relatively easy to implement.’

Fubini believes that practical application may not be far away. ‘Future development will be needed to adapt the method to a large influx of fibres suspended in water, and may require us to find out the optimal chelating agent concentration. But once found it could be applied to polluted waters, eluates from disused mines, and so on.’ –http://www.rsc.org