Making clean water at a lower cost could be on the horizon after researchers from the University of Texas at Austin and Penn State solved a complex problem that has plagued scientists for decades, so far.
A dehydration membrane removes salts and other chemicals from water, a process that is vital to the health of society, purifying billions of waters for agriculture, energy production and drinking. The idea may seem simple – push salt water through it and clean water will come out the other side – but there are complex things that scientists are still trying to understand.
The research team, in partnership with DuPont Water Solutions, solved an important aspect of this secrecy, opening the door to reduce clean water production costs. The researchers concluded that a detoxification membrane is inconsistent in density and high circulation, which can hold back performance. The uniform density at the nanoscale is the key to creating the amount of clean water that these organs can produce.
“Reverse osmosis membranes are widely used for purifying water, but there are many we don’t know about,” said Manish Kumar, associate professor in the Department of Civil Engineering, Architecture and Environment at UT Austin, who co-directed the research. “We couldn’t say for sure how water passes through, so all the improvements in the last 40 years have been done in the dark.”
The findings were announced today in Science.
The paper records an increase in efficiency in the organs tested by 30% -40%, meaning they can purify more water while using much less energy. This could lead to increased access to clean water and lower water bills for both individual households and large consumers.
A reverse osmosis membrane works by pressing the saline nutrient solution on one side. The minerals stay there as the water passes through. Although it is more efficient than non-membrane detoxification processes, it still takes a lot of energy, the researchers said, and the effectiveness of the organs could reduce that burden.
“Freshwater management is becoming a critical challenge worldwide,” said Enrique Gomez, a professor of chemical engineering at Penn State who co-directed the research. “Scarcity, drought – with growing weather patterns, this problem is expected to become even more important. The availability of clean water is critical, especially in low-resource areas.”
The research was funded by the National Science Foundation and DuPont, which produces multiple incineration products. The seeds were sown when DuPont researchers found that thick organs proved to be more dense. This came as a surprise as the conventional theory was that thickening reduces the amount of water flowing through the organs.
The team approached Dow Water Solutions, now part of DuPont, in 2015 at the Kumar-organized “water roof,” and they wanted to unravel this mystery. The research team, which also includes researchers from Iowa State University, developed a 3D reconstruction of a nanoscale membrane structure using state-of-the-art electron microscopes at the Materials Character Laber in Penn State. They model the way water passes through these organs to predict how effectively water could be purified based on structure. Greg Foss of the Texas Center for Advanced Computing helped paint these simulations, and most of the numbers were made on Stampede2, TACC’s supercomputer.
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