In Copley Science Center Room 217, ductwork climbs the wall like ivy, and the air hums with electric current. Inside, two students lean back from a lab table overflowing with PVC tubes, glass beakers, and white-hot heat lamps to talk shop. The topic of their conversation is membrane distillation, a method of water purification both students researched this summer during their Schapiro Undergraduate Research Fellowship (SURF) projects.
“Salt water in, fresh water out,” said Huma Jafree ’22, describing the process they believe will play a role in potentially solving the global fresh water shortage.
An international student majoring in Physics and minoring in Mathematics, Jafree worked on refining a water distillation method called air gap membrane distillation. In her project, titled “The Effect of Pore Size and Gap Size in Air Gap Membrane Distillation,” she heated salt water in one vessel until it turned to steam, after which it passed through a porous polymer membrane into a second chamber. There, she condensed the vapor particles into freshwater droplets by chilling them. The task before her was to tweak the width of the air gaps and the size of the pores to determine the most efficient form of water distillation.
That’s where Mary O’Sullivan ’23’s (Engineering major, Chemistry and Mathematics double-minor) SURF project, titled “Fabrication and Characterization of Melt Electrospun Membranes for Use in Membrane Distillation Systems,” came in. The Honors Program student and Colonial Beach native sought the best way to produce the same type of membrane used in Jafree’s experiments via a process called melt electrospinning. Aided by a heated, electrified needle, O’Sullivan melted a polymer—in her case, polypropylene, found in household objects like drinking straws, baby bottles, and yogurt containers—that was later assembled into fibrous membranes with pore sizes on the scale of microns via computer guidance.
“We’re both interested in whether there’s a membrane thickness or air gap size that’s better than what’s available commercially,” Jafree said of their work, conducted under the tutelage of faculty mentor and Engineering Professor Jim McLeskey. “The market right now is limited, so if we are able to make the membranes from scratch, the parameters of our research would open up in so many ways.”
The Future of Water Desalination?
Traditionally, scientists need to heat water to its boiling point—100 degrees Celsius—for it to evaporate, thereby separating it from the water’s content they don’t want, whether it’s salt, ammonium, or sewage. “The nice thing about membrane distillation is that you don’t need to bring water to its boiling point. It just has to be hot, even 50 degrees Celsius, which means saving energy and reducing costs,” O’Sullivan explained.
Jafree elaborated on the process’ potential boon to water desalination efforts by saying, “This could be a system that warms sea water using waste heat or solar energy and cools it using cold ocean water. In essence, it would take little energy with low costs to heat the ocean water to the right temperature to produce fresh water.”
So what did a typical day in the lab look like for Jafree and O’Sullivan? “Lots of prep work,” O’Sullivan said. That’s because both her and Jafree’s systems took several hours to complete a single “run,” culminating in one new membrane or one competed water distillation cycle, respectively. While their systems worked their magic, the duo prepared for their SURF Symposium poster presentations, cleaned equipment, and noted their results. At times, those results provided more questions than answers.
Process Makes Progress
Jafree identified a flaw in her procedure only three weeks before she was to present her findings at the SURF Symposium. At that point she had completed 60 runs with her distillation system, each one lasting about three hours. She realized with a sinking feeling that she would need to perform each run again, which would run well past the scope of her nine-week fellowship. Still, she was glad she corrected the issue when she did, and that subsequent runs produced results she was happy with.
O’Sullivan also encountered setbacks as she refined the development process to produce membranes on par with those available for sale. “We have days where we make a ton of progress and things are clicking,” O’Sullivan said. “Other days it’s one step forward, two steps back.”
It’s a pattern that led the duo to adopt a shared mantra in the lab—progress! inflected with an exclamation point—and even keep a small piece of wood handy to knock on when research was going well. Both students said the SURF research process helped remedy any “glorified notions of what research should look like instead of what it is,” Jafree noted. They praised Dr. McLeskey for giving them the freedom to try new things and the support they needed when obstacles arose.
“It’s always a conversation with Dr. McLeskey,” Jafree said. “He lets you own your project by giving advice without making it black and white. He encourages you to try new things and see where it takes you.”
“Research is not going to be perfectly smooth,” O’Sullivan added. “There’s a poster a few doors over that says, ‘If we knew what it was we were doing, it would not be called research, would it?’ That sums it up perfectly.”