Science News
“Graphene Sheets for Small Molecule and Salt Separation”
Date : 04-Feb-2019
MIT researchers have developed a technique to fabricate large squares of graphemes that can filter out small molecules and salts.
For the very first time, MIT engineers have found a way to directly “pinprick” microscopic holes into graphene. With this technique, the engineers have prepared postage stamp size sheets of graphene with pores that could make filtering certain molecules out of solutions vastly more efficient. Such holes in graphene would typically be considered unwanted defects. However, the MIT team has proved that defects in graphene can be an advantage in fields such as dialysis. Typically, much thicker polymer membranes are used in laboratories to filter out specific molecules from solution, such as proteins, amino acids, chemicals, and salts. If it could be tailored with pores small enough to let through certain molecules but not others, graphene could substantially improve dialysis membrane technology: The material is incredibly thin, meaning that it would take far less time for small molecules to pass through graphene than through much thicker polymer membranes.
MIT engineers also found that simply turning down the temperature during the normal process of growing graphene will produce pores in the exact size range as most molecules that dialysis membranes aim to filter. The new technique could thus be easily integrated into any large-scale manufacturing of graphene, such as a roll-to-roll process that the team has previously developed.
News Source: MIT News
http://news.mit.edu/2018/graphene-sheets-holes-molecular-separation-1009