Synchrotrons and Neutrons Could Unlock the Next Generation of Water Treatment

Every drop of water that flows through a treatment plant hides a nanoscale drama. Ions jostle at mineral surfaces, polymer membranes swell as water molecules thread through them, and foulants accumulate in layers too thin to see with any conventional microscope. For decades, engineers have designed water treatment systems largely by trial and error, measuring what goes in and what comes out while remaining blind to the molecular events in between. Now a team of researchers from major US synchrotron and neutron user facilities argues that this blindness is no longer necessary, and that the tools to see it have been sitting largely unused by the water treatment community all along.

In a review published in Nature Water, scientists led by Matthew Landsman of Arizona State University and Lawrence Berkeley National Laboratory, together with colleagues from SLAC National Accelerator Laboratory, Oak Ridge National Laboratory, Brookhaven National Laboratory, Argonne National Laboratory and several universities, lay out a detailed case for expanding the use of synchrotron X-ray and neutron techniques in water treatment research. These facilities, which accelerate electrons to near light speed or generate intense beams of neutrons, have transformed fields from structural biology to battery development. Yet the water treatment community, the authors contend, remains a strikingly small fraction of their user bases, leaving transformative research opportunities untapped.

The technical argument rests on what these beams can actually reveal. Synchrotron X-rays are extraordinarily bright and tunable, spanning energies from tender X-rays that probe light elements like carbon and nitrogen to hard X-rays that penetrate thick samples and resolve atomic coordination around metals. Techniques such as X-ray absorption spectroscopy can determine the oxidation state and local bonding environment of contaminants like arsenic or chromium in real water matrices. Small-angle X-ray scattering can measure the size and arrangement of colloids and polymers in solution. X-ray computed tomography can map the three-dimensional internal structure of membranes and porous sorbents at resolutions reaching tens of nanometers. Neutrons, meanwhile, offer a complementary superpower: they are exceptionally sensitive to hydrogen, meaning they can directly visualize water itself as it moves through materials, something X-rays struggle to do because hydrogen scatters X-rays so weakly.

What makes the review particularly compelling is its emphasis on in situ and operando experiments, meaning studies conducted while a treatment process is actually running under realistic conditions. Traditional characterization typically requires drying, freezing or otherwise preparing samples, which can fundamentally alter the structures being studied. Modern user facilities increasingly offer sample environments that allow researchers to study flowing water, applied voltages, pressure and temperature while collecting data. The authors point to examples such as operando small-angle neutron scattering studies of silica fouling in reverse osmosis systems, in situ X-ray scattering measurements of concentration polarization layers during cross-flow ultrafiltration, and operando ambient-pressure X-ray photoelectron spectroscopy that directly probes the chemistry of polymer membranes as they absorb water and ions.

These dynamic measurements matter because water treatment performance is governed by nanoscale processes that unfold in real time. Fouling, the accumulation of unwanted material on membranes and sorbents, is a prime example. It is the dominant cost driver in membrane-based desalination and water reuse, yet its molecular origins remain poorly understood. X-ray and neutron techniques can reveal the composition, structure and evolution of fouling layers as they form, distinguishing between mineral scaling, organic adsorption and biofilm development. The authors cite work using X-ray absorption spectroscopy to identify the mechanisms of calcium and silicon fouling on reverse osmosis membranes in wastewater reclamation, and neutron reflectometry studies that expose the interfacial microenvironment driving electrochemical reactions.

The review also highlights opportunities in three specific technology areas where facility access could accelerate progress. Membranes for brine management, including zero and minimal liquid discharge systems, could benefit from molecular-level understanding of ion transport and membrane structure. Catalysts for contaminant degradation, such as single-atom catalysts embedded in membranes that activate hydrogen peroxide to destroy pollutants, could be characterized under operating conditions to identify their true active sites. Sorbents for resource recovery, including materials that selectively capture phosphate, ammonia nitrogen or critical minerals from wastewater, could be optimized by directly observing how their binding sites interact with target ions in complex water matrices.

Neutron techniques deserve particular attention in this context because of their unique sensitivity to light elements and their ability to distinguish isotopes. Hydrogen-deuterium contrast neutron radiography, for instance, can track water exchange and two-phase flow in porous materials by substituting heavy water for normal water. Quasielastic neutron scattering can measure the dynamics of confined water in polymer membranes on picosecond to nanosecond timescales, revealing how water molecules move through the aromatic polyamide layers of reverse osmosis membranes. These measurements directly connect molecular motion to macroscopic water permeability, offering a level of mechanistic insight that conventional laboratory techniques cannot match.

The authors also emphasize the growing role of advanced computational modelling coupled with facility experiments. Machine learning is increasingly used to process the enormous datasets generated by modern detectors, such as the 500-kilopixel X-ray photon correlation spectroscopy measurements that resolve dynamics on microsecond timescales. Multimodal experiments that combine X-ray and neutron tomography simultaneously, such as the NeXT system at the National Institute of Standards and Technology, allow researchers to register complementary information about structure and water distribution in the same sample. The integration of artificial intelligence with high-throughput scattering and imaging is proposed as part of a next-generation discovery pipeline that could dramatically accelerate materials development.

Access to these facilities is more attainable than many water researchers realize. User facilities at national laboratories typically provide beamtime free of charge to researchers whose proposals are accepted through competitive peer review, and many offer dedicated staff scientists who help design experiments and operate complex sample environments. The authors argue that expanding the user base at these facilities will require deliberate outreach, training programs and the development of standardized experimental workflows that lower the barrier to entry for water treatment researchers unfamiliar with synchrotron or neutron techniques.

The stakes extend well beyond academic curiosity. The authors frame their argument in terms of global water, resource and energy security, noting that molecular-level design insights bridge laboratory-scale discoveries to system-level improvements in real treatment infrastructure. As climate change intensifies water scarcity and as industries seek to recover valuable materials from waste streams, the ability to rationally design next-generation membranes, catalysts and sorbents becomes increasingly urgent. The review suggests that the water treatment community stands at a threshold, where the sophisticated characterization infrastructure built over decades at national laboratories could finally be brought to bear on one of humanity’s most fundamental challenges: ensuring clean water for all.

Subject of Research: Water treatment research opportunities at synchrotron and neutron user facilities

Article Title: Water treatment research opportunities at synchrotron and neutron user facilities

Article References: Landsman, M. R., Hesse, S. A., Aydogan-Gokturk, P., Yao, C., Bechtel, H. A., Dudchenko, A. V., Hexemer, A., Jiang, Z., Katz, L. E., Kumar, M., Urban, V. S., Waluyo, I., Mauter, M. S., Tassone, C. J., & Crumlin, E. J. (2026). Water treatment research opportunities at synchrotron and neutron user facilities. Nature Water, 4(10), 1244-1258. https://doi.org/10.1038/s44221-026-00723-9

Image Credits: AI Generated

DOI: 10.1038/s44221-026-00723-9

Keywords: synchrotron, neutron scattering, water treatment, membranes, desalination, fouling, X-ray absorption spectroscopy, operando characterization, user facilities, Nature Water, Water, treatment