Sand has been used to purify drinking water throughout the world for more than 6,000 years. Mainak Majumder and colleagues, Monash University, Australia, coated sand grains with graphite oxide (GO) nanosheets. Their “super sand” showed five times the filtering capacity of regular sand in removing mercury and a dye molecule from water.

In the mercury test, ordinary sand was saturated within 10 min of filtration, while the super sand absorbed the heavy metal for more than 50 min.

Their studies suggest that it could be used to improve sand filtration in a cost-effective way.

• Engineered Graphite Oxide Materials for Application in Water Purification,
  Wei Gao, Mainak Majumder, Lawrence B. Alemany, Tharangattu N. Narayanan, Miguel A. Ibarra, Bhabendra K. Pradhan, Pulickel M. Ajayan,
  Appl. Mater. Interfaces 2011, 3 (6), 1821–1826.
  DOI: 10.1021/am200300u