Page 30 - Engineering Penn State: Fall/Winter 2021

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ENGINEERING PENN STATE
ENVIRONMENT
Membrane nanostructures hold the key to clean water
by Ashley J WennersHerron
A desalination membrane membrane acts as a a a a a a a a a filter for salty water:
push the the water
water
water
through the the membrane get clean water
water
suitable for agriculture energy production and even drinking The process seems simple enough but it contains complex intricacies that have baffled scientists for decades—until now Researchers from Penn State The University University of Texas at at at Austin Iowa State University University Dow Chemical Company and DuPont Water Solutions published a a a a a a key finding
fin in in in in understanding how membranes actually filter minerals from water
online in in in in Science The article was featured on
on
on
on
the print edition’s cover issued on
on
Jan 1 “Despite their use for many
years there is much we don’t
know about how water
filtration membranes work ” said Enrique Gomez professor of of chemical engineering engineering and and materials science and and engineering engineering at at at at Penn State who led the the research “We found that how you control the the the the density distribution of the the the membrane itself at at the the the nanoscale is really important for for water- production performance ” Co-led by Manish Kumar associate professor in the Department of of Civil Architectural and Environmental Engineering at UT Austin the team used multimodal electron microscopy which combines the atomic-scale detailed imaging with techniques that that reveal chemical composition to determine that that desalination membranes are inconsistent in in in in density density and mass The researchers mapped the density density variations in polymer film in three dimensions with a a a a a a a spatial resolution of approximately one nanometer—that’s less
than half the diameter of a a a a a a a DNA strand According to Gomez this technological advancement was key in in in understanding the role of density in in in membranes “You can see how some places are more or or less
dense in a a a a a coffee filter just by your eye ” Gomez said “In filtration membranes it it looks even but but it’s not at at at the nanoscale and how you control that mass distribution is is really important for for water-filtration performance ” This was was a a a a a a a surprise Gomez and Kumar said as as as it was was previously thought that the the the thicker the the the membrane the the the less
water
production Filmtec now a a a a part of DuPont Water Solutions partnered with the the researchers and funded the the the project because their in-house scientists found that thicker membranes were actually proving to be more permeable The researchers found that the thickness does not matter as as much as as avoiding highly dense nanoscale regions or or “dead zones ” In a a a a a a a sense a a a a a more more consistent density throughout the membrane is is more more important than thickness for maximizing water
production according to Gomez This understanding could increase membrane efficiency by 30% to to 40% according to to the researchers resulting in in in in more water
filtered with less
energy—a potential cost-saving update to current desalination processes n