When you turn on a faucet, charge an electric vehicle or use products made with clean hydrogen, you may not realize that membranes — ultrathin films perforated with pores too small to see — make these modern processes possible. They purify water, recover valuable minerals and help power emerging clean-energy technologies.
But despite their enormous importance, researchers still don’t fully understand how water and ions move through these films at the molecular level.
A new invited perspective in Nature Water , led by Rice University researchers and international collaborators, aims to change that. The paper emerged from a workshop held in March at the Rice Global Paris Center , where experts from around the world gathered to discuss the future of membrane science. At the same event, Rice announced the launch of the Rice Center for Membrane Excellence (RiCeME), a hub focused on designing advanced membrane materials for water, energy and sustainability applications.
“This work sets the foundation for a new era of membrane science,” said Menachem Elimelech , corresponding author of the paper, the Nancy and Clint Carlson Professor in Civil and Environmental Engineering and director of RiCeME. “Our models have traditionally treated membranes as black boxes. Now, we’re beginning to understand transport at the molecular scale, which opens the door to designing far better membranes.”
“Seeing work like this take shape affirms why Rice invested in the Rice Global Paris Center in the first place,” added Caroline Levander , vice president for global strategy. “The workshops and conferences we host there are designed to create sustained, international intellectual exchange, and this perspective in Nature Water demonstrates how those conversations can translate into rigorous, collaborative research with real-world impact. It is tangible evidence that our global research ecosystem is functioning as intended.”
Membranes are central to processes we depend on every day, including desalination and water purification, safe wastewater reuse, recovering valuable elements such as lithium and producing green hydrogen. At the heart of all these technologies is the same goal: letting water or certain ions pass through while keeping others out. But existing membranes face trade-offs. Increasing speed often reduces selectivity, and improving selectivity can slow everything down.
“We can’t solve global water and energy challenges with incremental tweaks,” Elimelech said. “We need a deeper scientific understanding of what actually happens inside these membranes.”
The perspective highlights breakthroughs from three rapidly advancing areas of research:
Molecular simulations: Computer models now allow scientists to watch water and ions move through angstrom-scale pores — revealing that water flows in clusters, not as individual molecules, and that ions struggle to shed tightly bound “shells” of water needed to squeeze inside.
Nanofluidics and angstrofluidics: Experiments with single nanotubes and 2D slits show surprising behaviors, including ultrafast water transport, strong ion exclusion and even hints of quantum effects. These tiny “test channels” help researchers uncover the physics that governs real membranes.
Advanced experimental tools: New microscopy, X-ray and neutron techniques can probe the structure of membranes more precisely than ever, confirming that even the best-performing membranes have complex, dynamic pore networks.
By combining these approaches, researchers are beginning to map how water and ions navigate the dense, tangled pathways that make up a membrane, and they are helping to shed light on why some ions are rejected while others slip through.
The team outlines a multiscale strategy to connect molecular insights to real-world membrane design: first, study single, well-defined nanochannels to isolate fundamental behavior; second, build model membranes with many identical channels to understand collective transport; and third, apply this knowledge to improve commercial polymer membranes, which have much more complex structures.
“This is the bridge we’ve been missing,” Elimelech said. “If we can connect what happens at the scale of single molecules to performance at the scale of real devices, we can design membranes with unprecedented efficiency and selectivity.”
Notably, this perspective reflects the collaborative spirit that drove the Paris workshop — and the ambition behind RiCeME.
“Rice is uniquely positioned to bring together molecular modeling, nanofluidics, advanced materials and large-scale membrane engineering,” Elimelech said. “By uniting these strengths, we can rethink how membranes are designed and unlock solutions for clean water, sustainable chemistry and renewable energy.”
Nature Water
A multiscale perspective for understanding transport mechanisms in desalination and ion-selective membranes
17-Feb-2026