Credit: © 2008 Wiley

The need to remove hazardous by-products goes hand in hand with nuclear energy. Radioactive ions are discharged from nuclear power stations, and also by the mining industry, so materials that can irreversibly absorb large quantities of these ions from waste water are needed. To this end, natural materials such as clays and zeolites have proved useful because radioactive cations are preferentially exchanged with cations in the material. This exchange traps the radioactive cations, enabling them to be disposed of. However, synthetic cation exchange materials have been found to have much better selectivity.

Moreover, in absorbent materials that are not completely stable, the exchange process can cause structural collapse, which traps the radioactive ions permanently. Dong Jiang Yang and co-workers1 at Queensland University of Technology and Nankai University have now demonstrated this property with a layered titanate nanofibre, which has an interlayer containing exchangeable sodium cations. The observed absorption values for cations of similar sizes to various radioactive nanoparticles were higher than those for clays and zeolites, as well as other previously developed synthetic exchange materials.

The nanofibres can be synthesized easily and at low cost, they can be dispersed in solutions more effectively than clays and zeolites, and they can be separated from liquids using simple techniques.