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Graphene oxide: A better membrane, but no ‘silver bullet’ for desalination

In recent decades, arid regions around the world have turned to the seas for drinking water.

Desalination – removing salt from seawater – offers dry places from the Middle East to the American Southwest an alternative to scarce rainfall and groundwater. With 1.8 billion people projected to live “in countries or regions with absolute water scarcity” by 2025, the demand for solutions to water-supply challenges looks set to grow in coming years, according to the United Nations.

Better filtration membranes could make desalination more viable as one of these solutions. Most modern plants use reverse osmosis, an energy-intensive process of pumping seawater through membranes to filter out the salt.

Since the 1960s, these membranes have almost always been made of polymers. But recent research has aimed to reduce the pumping energy by instead making them from “nanomaterials.” On Monday, British researchers at the University of Manchester’s National Graphene Institute in England announced that they had developed a membrane from one such material: graphene oxide.

Their new membrane marks a step forward for desalination technology. But it still faces a challenging road to the world’s seawater treatment plants, suggesting that the search for solutions to humanity’s thirst is far from over.

“The big cost is the energy cost of desalination and the reliability of the membranes, how long they last,” explains Peter Gleick, co-founder and president emeritus of the Pacific Institute in Oakland, Calif. “I think that the current research results are a great step forward for both of those issues … but in the end, it’s really going to depend on our ability to commercialize this process.”

For more than three decades, Dr. Gleick has researched and worked to raise awareness of water availability issues. During that time, some cities have seen the cost per cubic meter of desalinated water drop by half, from $1.50 to 75 cents.

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