Mainak Majumder and colleagues note that sand has been used to purify water for more than 6,000 years, and sand or gravel water filtration is endorsed by the World Health Organization. Their studies of a nanomaterial called graphite oxide (GO) suggest that it could be used to improve sand filtration in a cost-effective way, they write.
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. 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, the scientists discovered. 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 functionalized GO particles on the sand grains to further enhance contaminant removal efficiencies," they write.