Graphene-based dialysis membrane filters 10 times faster than current materials
It can be 10 times stronger than steel, is light and superconductive, and is being used to revolutionize everything from lightbulbs to the internet. In the latest graphene-enabled innovation, a team of MIT engineers has potentially revolutionized the process of dialysis by creating a new membrane from this wonder material that is able to filter nanometer-sized molecules from solutions up to 10 times faster than current dialysis systems.
As well as hemodialysis, the process of removing waste from blood in patient's whose kidneys are not functioning properly, dialysis is also used by scientists to isolate specific molecules, purify drugs and remove unwanted residue from chemical solutions. Modern dialysis membranes work reasonably slowly due to their thickness, but this new graphene membrane can speed things up due to being less than one nanometer thick.
"Because graphene is so thin, diffusion across it will be extremely fast," says Piran Kidambi from MIT's Department of Mechanical Engineering. "A molecule doesn't have to do this tedious job of going through all these tortuous pores in a thick membrane before exiting the other side. Moving graphene into this regime of biological separation is very exciting."
The MIT team developed a process to create an ultrathin layer of graphene that essentially functions as a molecularly selective sieve. The team then created different membranes with pores in a variety of sizes. This highly specific ability to tailor the size of the pores allowed the researchers to test the different membranes' ability to filter specific molecules.
One graphene membrane with designed with very small pores to let through potassium chloride molecules that are only 0.66 nanometers wide. The membrane was found to efficiently let through those molecules, but block larger ones such as L-tryptophan, which measures just 0.2 nanometers wider.
The researchers note that although this new dialysis membrane has particular uses in speeding up lab-scale separation processes, it also has potential to improve hemodialysis systems. With current hemodialysis treatments taking up to four hours for a single patient, any reduction would definitely be welcome.
The team's study was published in the journal Advanced Materials.