Membrane separations are a crucial process in various industries, from biotechnology to petrochemicals to water treatment. Seth Darling, head of the Advanced Materials for Energy Water Systems (AMEWS) Center at Argonne National Laboratory, emphasizes the importance of efficient separations achieved through membranes. However, most commercial membranes have varying pore sizes, making sharp separations challenging. Darling and his team have been studying isoporous membranes, where all pores are the same size, to improve selectivity in size-based separations. Hindered transport, caused by fluid resistance in the pore, limits the sharpness of separations in current membranes.
Darling’s research focuses on pores around 10 nanometers in diameter, where a perfect membrane could potentially achieve separations with as little as a five percent size difference. In their study, the team discovered that solute molecules could be given multiple chances to pass through the pore by cycling the feed solution for weeks. This approach led to sharper separations, moving the separation curve towards a more defined function. The insights gained from isoporous membranes could be applied to existing materials to increase solutes’ chances of passing through, potentially revolutionizing industrial membrane separations and impacting various sectors of the economy.
The phenomenon of hindered transport, where solutes experience resistance in the pore, has been a significant limitation in achieving sharp separations in commercial membranes. By studying isoporous membranes, Darling’s team uncovered a dynamic that challenges the assumption that solutes only have one opportunity to pass through a pore. Cycling the feed solution for an extended period allowed solutes to make multiple attempts, leading to improved separation sharpness. With further research and process refinement, the team believes clear, sharp separations can be achieved by matching pore size to solute size.
The success of this research could have far-reaching implications for membrane separations across various industries. By overcoming hindered transport limitations and improving selectivity in size-based separations, industrial processes could become more efficient and cost-effective. DARPA’s Office of Basic Energy Sciences provided support for this work, highlighting the potential impact of this research on advancing membrane separation technologies. As scientists continue to explore the possibilities of isoporous membranes and enhance process design, the future of membrane separations looks promising in improving efficiency and selectivity in a wide range of applications.
