With much of the world still lacking access to safe drinking water, the need for more efficient filtration systems is higher than ever. Wei Gao, from Rice University in Texas, has however invented a graphite-coated type of sand that is cheap to produce and much more effective at filtering water.
He called it the “super sand.” Each and every grain of this sand is coated in an oxide of graphite – a material you’re surely acquainted with from pencils. He tells the BBC that regular coarse sand is a lot less effective than fine sand when the water is contaminated with pathogens, organic materials and heavy metal ions.
“This material demonstrates comparable performance to some commercially available activated carbon materials,” says Dr Mainak Majumder from Monash University in Melbourne, Australia. “But given that this can be synthesized using room temperature processes and also from cheap graphite sources, it is likely to be cost-efficient,” he adds.
Gao explains the technique they used to produce the super sand. She says it involves dispersing graphite oxide into water and mixing it with regular sand. “We then heat the whole mixture up to 105C for a couple of hours to evaporate the water, and use the final product – ‘coated sand’ – to purify polluted water.”
Cleaning water is a must for today’s technology to solve cheaply and energy efficiently, since the World Health Organization says that “just 60% of the population in Sub-Saharan African and 50% of the population in Oceania [islands in the tropical Pacific Ocean] use improved sources of drinking-water.”