Sunscreen, soda...voila

Last Updated: Saturday 04 July 2015

A cheap way to clean up radioactive waste

a common ingredient of sunscreens, when mixed with another ingredient of soaps, can clean up wastewater containing radioactive material. Upon heating, titanium dioxide and caustic soda form a ceramic. This, a group of Australian and Chinese researchers found, could absorb radioactive material. With the demand for nuclear material for electricity increasing across the world, this ceramic could find wider use: removing radioactive ions from wastewater of nuclear reactors and mines.

This ceramic has layers of nanofibres, with sodium ions in them. When added to wastewater from nuclear plants and uranium mines, the radioactive material got attracted into the spaces between the layers, where it displaced sodium. After absorbing the toxin to its capacity, the nanofibers collapsed--because the ceramic is unstable--locking in it the toxic material.

This action is irreversible. The fibres can be removed from the wastewater simply by filtration, sedimentation or centrifugation. A paper in the journal Advanced Materials (Vol 20) said the solid material left behind is stable when exposed to radiation, chemicals, heat and stress and can be disposed safely.

"The fibres are stable as stones," said H Y Zhu, one of the authors. "The used fibres can be buried away from residential areas. This would allow the radioactive material to decay. There is no safety issue," said the scientist of the Queensland University of Technology in Brisbane, Australia.

The nanomaterial could replace materials used now, like the natural zeolite, which traps radioactive ions in microscopic holes. The material can then be pressed to secure the ions inside. But nanomaterial is safer and more efficient, because it is selective. It is faster, too, taking up 80 per cent of it capacity within 24 hours. In contrast, synthetic absorption material used now, like layered g-ZrP, take up to 110 hours.

Titanium dioxide and caustic soda are cheap and easily available. The researchers are looking for industrial partners to scale up the technology.

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