New research could increase desalination membrane efficiency by 30% to 40% resulting in more water filtered with less energy, a potential cost-saving update to current desalination processes.
“Reverse osmosis membranes are so widely used for cleaning water, but there’s still a lot we don’t know about them,” Kumar said.
“In filtration membranes, it looks even, but it’s not at the nanoscale, and how you control mass distribution is important for water-filtration performance.”
Filmtec, now a part of DuPont Water Solutions, which makes numerous desalination products, partnered with the researchers and funded 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 much as avoiding highly dense nanoscale regions, or “Dead zones.” In a sense, a more consistent density throughout the membrane is more important than thickness for maximizing water production.
Polyamide membranes have been used in large-scale desalination for decades. Because of the thinness of the membranes and their internal variability, it has been hard to determine which aspects of the membranes most affect their performance.
Abstract Biological membranes can achieve remarkably high permeabilities, while maintaining ideal selectivity, by relying on well-defined internal nanoscale structures in the form of membrane proteins.
Pore density fluctuations are detrimental to water transport, which makes systematic control over nanoscale polyamide inhomogeneity a key route to maximizing water permeability without sacrificing salt selectivity in desalination membranes.