Water, water everywhere and not a drop to drink. Humans have been facing the potable water dilemma long before California had drought problems, but a team of researchers in the United Kingdom may have solved that problem once and for all. According to BBC News, scientists from the University of Manchester have developed a graphene sieve to separate salt from seawater. In a report published in the journal Nature Nanotechnology, the team describes how their graphene oxide sieve could adequately filter salts and ultimately provide clean drinking water to millions without access.
While similar graphene-based filters have been difficult to manufacture at an industrial level in the past, the researchers have found a chemical derivative known as graphene oxide to be more practical. Led by Dr. Rahul Nair, the team hopes this discovery will eventually reduce production costs and make seawater-filtering systems widely available. The challenge lies in producing a sieve that has small enough holes to filter out commonly found salts while allowing water molecules to pass.
So far, Dr. Nair’s graphene oxide sieve has proven to be adept at sifting the larger salts, organic molecules, and nanoparticles that don’t belong in clean drinking water. But to remove dissolved salts, the membrane’s holes need to be so tiny as to distinguish between pure water molecules and salt molecules encased in a “shell” of water. Dr. Nair describes the genius behind his team’s membrane, telling BBC News, “Water molecules can go through individually, but sodium chloride cannot. It always needs the help of the water molecules. The size of the shell of water around the salt is larger than the channel size, so it cannot go through.”
Most importantly, Dr. Nair’s sieve allows water molecules to pass through quickly, a key factor in addressing the world’s vast water needs. With nearly a fifth of the world’s population (aka 1.2 billion people) living in areas plagued by water scarcity, this discovery could not have come at a more crucial time. Moving forward, Dr. Nair’s team plans on testing the membrane’s durability and its cost-effectiveness on a larger scale. In an article supplementing Dr. Nair’s report, Dr. Ram Devanathan wrote, “The selective separation of water molecules from ions by physical restriction of interlayer spacing opens the door to the synthesis of inexpensive membranes for desalination.” In other words, we’re on the right track.