Tiny particles of pure silica coated with an active material
could be used to remove toxic chemicals, bacteria, viruses, and other
hazardous materials from water much more effectively and at lower cost
than conventional water purification methods, according to researchers
writing in the current issue of the International
Journal of Nanotechnology.
Peter Majewski and Chiu Ping Chan of the Ian Wark Research
Institute, at the University of South Australia, explain that the
availability of drinking quality water is fast becoming a major
socio-economic 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. The
Australian team suggests that nanotechnology could provide a simple
answer to the problem.
The researchers have investigated how silica particles can be
coated easily with a nanometre-thin layer of active material based on a
hydrocarbon with a silicon-containing anchor. The coating is formed
through a chemical self-assembly process so involves nothing more than
stirring the ingredients to make the active particles.
These 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 at pH ranges of drinking water by stirring the coated
particles in the contaminated water for up to one hour and filtering
the powder," the researchers say. They point out that the filtration
process occurs through an electrostatic attraction between the
pathogens and the surface engineered particles.
The recent report entitled 'Water for People - Water for Life'
of the World Water Assessment Program of the UNESCO says that more than
6000 people die every day due to water-related diseases, including
diarrhoea, worm infections, and infectious diseases. In addition,
organic pollutants from industrial waste water from pulp and paper
mills, textiles and leather factories, steel foundries, and
petrochemicals refineries, are a major cause of illness in parts of the
world where regulations do not necessarily protect people from such
industrial outflows. The team's nanotech approach to water purification
could help prevent disease and poisoning for potentially millions of
people.
Posted 21st February 2008
