AUSTIN, Texas – The production of clean water at a lower cost may be imminent after researchers at the University of Texas at Austin and Penn State solved a complex problem that has so far surprised scientists.
Desalinating membranes remove salt and other chemicals from water, a process that is critical to the health of society, cleaning billions of gallons of water for agriculture, energy production and drinking. The idea seems simple – push salt water through and clean water comes out the other side – but it contains intricate intricacies that scientists are still trying to understand.
The research team, in partnership with DuPont Water Solutions, solved an important aspect of this mystery and opened the door to reduce the cost of clean water production. The researchers found that desalination membranes are inconsistent in density and mass distribution, which may hinder their performance. Uniform density on the nanoscale is the key to increasing the amount of clean water these membranes can create.
“Reverse osmosis membranes are widely used for water purification, but there are still many we do not know,” said Manish Kumar, associate professor in the Department of Civil, Architecture and Environmental Engineering at UT Austin. the research. “We could not really say how water moves through it, and all the improvements over the last 40 years have been made in the dark.”
The findings are in Science.
The paper documents an increase in efficiency in the tested membranes by 30% -40%, which means that they can purify more water while using significantly less energy. This can lead to increased access to clean water and lower water bills for individual homes and large users.
Reverse osmosis membranes work by applying pressure to the saline solution on one side. The minerals stay there while the water runs through. Although it is more efficient than non-membrane desalination processes, it still takes a large amount of energy, the researchers said, and improving the efficiency of the membranes can reduce the load.
“Freshwater management is becoming a major challenge around the world,” said Enrique Gomez, a professor of chemical engineering at Penn State who led the research. “Deficiencies, droughts – with increasingly severe weather patterns, the problem is expected to become even greater. It is extremely important to be available for clean water, especially in areas with few resources. ”
The National Science Foundation and DuPont, which manufactures numerous desalination products, funded the research. The seeds were planted when DuPont researchers found thicker membranes to be more permeable. This was a surprise because the conventional knowledge was that the thickness reduces how much water can flow through the membranes.
The team teamed up with Dow Water Solutions, now part of DuPont, in 2015 on a “water summit” arranged by Kumar, and they were eager to solve this mystery. The research team, which also includes researchers from Iowa State University, developed 3D reconstructions of the nanoscale membrane structure using modern electron microscopes at Penn State’s Materials Characterization Lab. They modeled the path that water takes through these membranes to predict how efficiently water can be cleaned based on structure. Greg Foss of the Texas Advanced Computing Center helped visualize these simulations, and most of the calculations were performed on Stampede2, TACC’s supercomputer.