‘Stellar conditions’ could help turn saltwater to freshwater
Drought and population booms have a growing number of communities taking a closer look at building desalination plants, but turning saltwater to freshwater is more expensive than many would like.
Many researchers believe the magic bullet that lowers costs will be a high-strength membrane that can withstand the intense water pressure needed to desalinate water.
No one has found the perfect membrane so far, but Chad Sosolik of Clemson University could be on to something. The answer, he said, involves a piece of cutting-edge equipment that simulates stellar conditions on Earth.
Sosolik and his team of graduate students are using an electron beam ion trap, or EBIT, to poke atom-size holes in a strong, carbon-based material called graphene.
The holes could be made so small and precise that they would allow water molecules to pass, while filtering out the salt, Sosolik said.
Sosolik, an associate professor of physics, said today that he has begun to partner with industry and is launching a major push for government funding to advance the research.
“I want to show it works,” Sosolik said. “Just to see the physics of this would be interesting to me. If it does have a use, all the better.”
A solution couldn’t come too soon. Climate change is making rainfall less predictable and droughts more common, as rising populations increase demand for freshwater.
California’s historic drought has led to water restrictions across the state.
The American Southwest has been in drought for 11 of the past 14 years, directly affecting more than 64 million people, according to NASA. Countless others are indirectly affected because of the farms, orchards, and ranches that supply the rest of the United States.
While there are several ways to desalinate water, one involves high water pressure. Salt water is pushed through a membrane to filter out the salt. Pure water comes out the other side.
The ideal membrane would be ultra thin yet strong enough to hold up under the pressure.
For Sosolik and his team, the solution starts by putting dime-sized pieces of graphene into a vacuum system that lowers pressure about 1 billion times below Earth’s atmosphere.
“It’s basically like space,” Sosolik said.
At the molecular level, graphene looks like balls suspended in space and bonded by strings, except the balls are carbon atoms and the strings are electrons. A single atom can be a hard target to hit, so Sosolik has found a way to widen the target.
Sosolik shoots an ion at the graphene. But it’s no ordinary ion. With the EBIT, Sosolik can control how many electrons surround the ion. That’s key to what happens next.
As the ion approaches the graphene, it starts sucking up electrons from the graphene. Remember– those electrons bond together the carbon atoms. So the weakened bonds make it easier to blast aside the carbon atom.
You no longer need a direct hit. A glancing blow will do the trick.
The work that Sosolik does is new, even to physicists. The highly charged ions he creates in the EBIT don’t occur naturally on Earth. Their natural environment is in stellar matter.
The United States has six EBITs, and one of them is in the basement of Kinard Hall on Clemson’s main campus.
With the EBIT, Sosolik is shooting the highly charged ions he creates at different kinds of material, including graphene, to see what happens. It shows promise for creating new industrial materials, and new ways of treating tumors in the body.
Mark Leising, chair of the Department of Physics and Astronomy, said that Sosolik is breaking new ground with his research.
“New instruments, even those driven purely by scientific curiosity, often have unforeseen practical applications,” Leising said. “Chad was instrumental in getting the EBIT to campus, and now he’s finding new uses for it. It’s a rare scientific tool that Clemson is fortunate to have on campus.”
Anand Gramopadhye, dean of the College of Engineering and Science, said that he stands behind Sosolik as he pushes to further the research.
“Even in today’s modern times providing access to clean water is one of the grand challenges facing society,” Gramopadhye said. “Close to a 800 million do not have that access. Hence, the work that Dr. Sosolik is doing is not only important for its scientific merit but also for the transformative impact it can have.”