Toxic removal

Tiny particles of pure silica coated with an active material could be used to remove toxic chemicals, bacteria and viruses from water much more effectively and at a lower cost than conventional water purification methods, according to Australian researchers.

The availability of drinking quality water is fast becoming a major issue across the globe, especially in the developing world. However, water purification technology is often complicated, requires sophisticated equipment and is expensive to run and maintain. Moreover, it usually requires a final costly disinfection stage.

Now, Peter Majewski and Chiu Ping Chan of the Ian Wark Research Institute at the University of South Australia, suggest that nanotechnology could provide a simple answer to the problem.

The researchers developed silica particles coated with a nanometre-thin layer of active material based on a hydrocarbon with a silicon-containing anchor. The coating itself was formed through a chemical self-assembly process so involved nothing more than stirring the ingredients to make the active particles.

The active particles, so-called Surface Engineered Silica (SES), were then tested to demonstrate that they could remove biological molecules, pathogens such as viruses like the Polio virus, bacteria like Escherichia coli, and Cryptosporidium parvum, which is a waterborne parasite.

'The results clearly show that organic species can efficiently be removed from drinking water by stirring the coated particles in the contaminated water for up to one hour and then filtering the powder,' the researchers said. They point out that the filtration process occurs through an electrostatic attraction between the pathogens and the surface engineered particles.

The team believes that its nanotech approach to water purification could help prevent disease and poisoning for potentially millions of people.