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Engineers develop better graphene sieve that could advance clean water efforts

Posted by on Wednesday, September 23, 2020 in News.

Developing atomically thin graphene membranes used to separate salt from water is extraordinarily complex and the effort grows more crucial as population growth, industrialization and climate change strain freshwater resources.

Vanderbilt engineering researchers report a breakthrough in scalable fabrication of graphene membrane with a sealing technology that corrects variations in the pore size so they remain small enough to trap salt ions and small molecules but allow water to pass.

One of the most complex engineering challenges when making membranes so thin is to maintain integrity in the uniformity of the pores, which entails drilling atomically precise holes in a one-atom thick sheet of carbon atoms. “A single large hole can cause high leakage and compromise membrane performance,” said Piran Kidambi, assistant professor of chemical and biomolecular engineering.

“How do you poke trillions of holes between the size of 0.3 and 0.6 nanometers over a square centimeter of material that is just one-atom thick? That is 3 angstroms tolerance using processes that are scalable and roll-to-roll manufacturing compatible,” Kidambi said. An angstrom is one ten-billionth of a meter.

Read the full article HEREKidambi and team members have designed a simple defect-sealing technique based on a gatekeeper analogy.  While most prior studies formed holes in graphene membranes as a final step, this team flipped the process on its head. They formed holes in the graphene first using a low-temperature chemical vapor deposition (CVD) process followed by ultra violet light in the presence of ozone gas and used the size of the holes as a gatekeeper.

Read the full article HERE.