A new method has been developed by scientists to transform ordinary sand into a "super sand" used to purify drinking water.
The new material with five times the filtering capacity of regular sand could be a low-cost boon for developing countries, where more than a billion people lack clean drinking water.
Mainak Majumder and colleagues note that sand has been used to purify water for more than 6,000 years, and the World Health Organization endorses sand or gravel water filtration.
Their studies of a nanomaterial called graphite oxide (GO) suggest that it could be used to improve sand filtration in a cost-effective way.
The researchers used a simple method to coat sand grains with graphite oxide, creating a "super sand" that successfully removed mercury and a dye molecule from water.
The scientists discovered that in the mercury test, ordinary sand was saturated within 10 minutes of filtration, while the super sand absorbed the heavy metal for more than 50 minutes.
"Its filtration performance is comparable to some commercially available activated carbon," the scientists said.
"We are currently investigating strategies that will enable us to assemble functionalised GO particles on the sand grains to further enhance contaminant removal efficiencies," they wrote.
The study has been published in the ACS journal Applied Materials and Interfaces.