Scientists, led by an Indian-origin researcher, have claimed that a low-cost coating can be well applied to sand for wide-scale purification of water in developing countries, saving millions of lives every year.
Sand, an abundant natural resource, has been used to clean polluted water for six millennia.
Filtration using sand in its natural form is endorsed by World Health Organisation as a water purification process.
Now, Mainak Majumder of Monash University and his international team, which included researchers from Rice University in Houston, have significantly enhanced the natural filtering properties of sand by coating it with a nanomaterial called graphite oxide in their research.
The scientists changed the structure of graphite, a material found in pencils, to dramatically increase its surface area before coating coarse grains of sand.
Increasing the surface area of the sand caused a corresponding increase in the material's ability to filter contaminants.
The research, published in the ACS Applied Materials & Interfaces, indicated that untreated sand became saturated after 10 minutes of filtration, while the GO-coated 'super sand' absorbed contaminants for more than 50
Majumder said the super sand's performance was comparable to some commercially available activated carbon materials, which are used for filtration purposes.
"By increasing its surface area, we've improved the filtering capability of sand so it's not only more effective in removing contaminants but still filters relatively quickly, making it a viable option for water purification," he said.
Majumder said the other big advantage of the super sand is that it is relatively cheap to produce.
"Given that the functional carbon can be synthesised using room temperature processes and also from cheap graphite sources, such as mining by-product, it's likely to be cost-efficient," he said.
Access to clean water is a significant challenge for the global population.
The WHO reports that, annually, access to safer water could prevent 1.4 million deaths from diarrhoea; 500,000 deaths from malaria and 860,000 deaths from malnutrition.
"We hope that in the future our technology will help to improve the living conditions of people facing water scarcity," said Majumder.
