A low-cost coating applied to sand could provide a means to purify water, saving millions of people’s lives in developing countries each 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 the World Health Organization (WHO) as a water purification process.
Now, a team led by Dr Mainak Majumder from the Monash Department of Mechanical and Aerospace Engineering in Australia, together with researchers from Rice University in Houston, has enhanced the natural filtering properties of sand by coating it with a nanomaterial called graphite oxide (GO).
The coating effectively increased the surface area of the sand, causing a corresponding increase in the material’s ability to filter contaminants.The research indicated that, while untreated sand became saturated after 10 minutes of filtration, the GO-coated ‘super sand’ absorbed contaminants for more than 50 minutes.
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 that it is not only more effective in removing contaminants, but still filters relatively quickly, making it a viable option for water purification.’
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 byproduct, it is likely to be cost efficient.’
The research was funded by Nanoholdings, a US venture capital company engaged in the commercialisation of this technology.