Having clean water is a luxury that’s only available to a portion of the global population – approximately one in eight people lack access to safe water supplies, and 3.575 million people die each year from water-related disease. In an effort to help find a viable solution for this crisis, researchers at Rice University report that sand, long used as a water cleaning agent, combined with the added benefit of a graphite oxide coating may be be the perfect recipe for what they are calling “super sand.” One of the problems associated with using the uncoated sand to purify water is that it does not have a particularly high retention for organic contaminants or heavy metal irons. With the water soluble graphite oxide coating the sand’s ability to absorb these materials is increased making the purification process faster and more effective.
This magic coating is achieved when nanosheets of graphite are made to have both hydrophilic (water-loving) and hydrophobic (water-hating) properties. When the sheets are combined into a solution with sand they self-adhere around the granules leaving the hydrophilic parts exposed. It’s this combo that increases the sand’s ability to absorb water-soluble contaminants and its water cleaning abilities.
Pulickel Ajayan, a chemistry, mechanical engineering and materials science professor at Rice, along with collaborators from Georgia and Australia, ran two experimental processes to determine the effectiveness of the graphite coated sand – mercury and Rhodamine B dye. Through these tests they found that the regular sand’s capacity to absorb mercury tapped out within 10 minutes while the coated sand continued cleaning for more then 50 minutes. They had very similar results for the Rhodamine B. In an article published by Rice University they state the following, “The researchers found coated sand sequestered contaminants just as well as the commercially available active carbon filtration systems they tested.”