University researchers innovate faster-flowing desalination membrane

When considering the source of a refreshing glass of water, one might not immediately credit polymeric desalination membranes. These thin polyamide membranes act as filters, converting salty water into fresh, drinkable water. They are widely used for turning both brackish and seawater into fresh water.

Devin Shaffer, an assistant professor of civil and environmental engineering at the University of Houston (UH), has made a significant advancement in this field. He has developed a membrane that allows water to flow through up to eight times faster while effectively keeping out salt, thereby enhancing the efficiency and accessibility of desalination.

Shaffer's work is published in ACS Applied Materials and Interfaces. It addresses the common tradeoff between permeability—how much water can pass through—and selectivity—how well the membrane blocks salt and other impurities. Typically, if more water passes through, it may allow more salt as well, reducing effectiveness. Conversely, if more salt is blocked, it can slow down water flow, making processes like reverse osmosis and nanofiltration less efficient and costlier.

“We have developed a new type of ultrathin polyamide membrane with a unique, contorted structure that creates more open spaces or enhanced free volume within the material,” reports Shaffer.

“These new ultrathin contorted membranes break that trade-off by letting water through much faster without sacrificing salt rejection, making desalination systems more efficient and cost-effective,” he said.

According to Shaffer's insights on these advancements in membrane technology, desalination could become even faster and more energy-efficient. This development holds promise for reducing costs and increasing access to clean water globally.