Dendritic Nanosilica Captures Dysprosium in Five Minutes While Maintaining High Rare-Earth Selectivity

Highlights

• Researchers immobilized extractant DEHPA onto open fibrous nanosilica, creating D-DEHPA that reaches dysprosium adsorption equilibrium in approximately five minutes.
• The material achieved a modeled Langmuir maximum capacity of 153.8 mg/g and favored dysprosium over lanthanum by 17.3-fold and over terbium by 4.3-fold.
• D-DEHPA performed effectively in complex real-world matrices including industrial rare-earth sludge leachate and natural water from a mining area.
• The study suggests that restructuring the support material—rather than developing entirely new extractants—can dramatically improve rare-earth separation speed and efficiency.
• Key limitations remain: only five regeneration cycles were tested, and scale-up, continuous-flow operation, and techno-economic viability have yet to be demonstrated.

A new Desalination study by first author Fang Zhang, François Nkinahamira of Guangzhou University (opens in a new tab), and international collaborators reports a nanoscale material that could help address a stubborn rare-earth processing problem: increasing how much metal a sorbent holds can slow how quickly ions reach its active sites. The researchers immobilized the established extractant DEHPA onto open, fibrous nanosilica, creating D-DEHPA, which reached apparent dysprosium adsorption equilibrium in about five minutes, demonstrated a modeled maximum Langmuir capacity of 153.8 mg/g, and maintained heavy rare-earth selectivity in complex aqueous samples.

REEx Insight | Better Architecture, Not Exotic Chemistry

The researchers found a new way to capture and separate rare-earth elements much faster without giving up how much material can be collected. They attached a common rare-earth extraction chemical called DEHPA to tiny, sponge-like silica particles with an open, branching structure. This design allowed dysprosium—a valuable heavy rare earth used in high-performance magnets—to reach the material's active sites quickly. The material reached most of its dysprosium uptake in about five minutes, while also showing a high modeled capacity of 153.8 milligrams per gram. Importantly, it could tell very similar rare-earth elements apart, favoring dysprosium over lanthanum by 17.3 times and over terbium by 4.3 times.

It also continued to work in complicated real-world water samples containing many competing minerals. The big finding is that researchers may not need an entirely new extraction chemical to improve rare-earth separation; changing the structure of the material that holds the chemical may make existing extraction chemistry work much faster and more effectively. The results are promising, but the technology still needs to prove that it can work economically and reliably at industrial scale.

Study Methods and Results

Researchers immobilized four industrially relevant organophosphorus extractants—DEHPA, P507, Cyanex 272 and Cyanex 572—onto the same DFNS platform and compared their dysprosium uptake. D-DEHPA performed best and was advanced for detailed testing. The material also demonstrated notable selectivity. Its reported separation factor favored dysprosium over lanthanum by 17.3-fold and over its much more chemically similar neighbor terbium by 4.3-fold. Testing extended beyond simplified laboratory solutions to an industrial rare-earth sludge leachate and dilute natural water from a rare-earth mining area. The researchers reported near-quantitative Dy³⁺ removal from the natural-water matrix and useful separation performance after five regeneration cycles.

Limitations and What Comes Next

This is promising laboratory-scale separation science—not yet an industrial breakthrough. Five regeneration cycles do not establish commercial durability, and adsorption capacity does not automatically translate into high-purity, saleable separated rare-earth oxide. Scale-up, continuous-flow operation, nanosilica manufacturing cost, extractant stability and loss, desorption and product recovery, waste generation, and full techno-economic performance remain to be demonstrated.

That distinction is important because mature solvent extraction remains the industrial benchmark, offering high throughput and decades of operating experience despite its solvent use, waste, and process complexity. The real test now is whether D-DEHPA can translate impressive laboratory kinetics and selectivity into continuous processing, long-term cycling, and ultimately competitive industrial economics.

REEx Connect

François Nkinahamira — Assistant Researcher/Assistant Professor, Guangzhou University; research focuses on functional materials and rare-earth recovery.

Guangzhou University — Researchers on the study received support from the Natural Science Foundation of Guangdong Province, National Natural Science Foundation of China and a Guangdong university innovation program.

Elsevier / Desalination — Publisher and peer-reviewed journal in which the study appears.

Citation: Zhang F., Zong Y., Rong H., Cui B., Duan L., Ndagijimana P., Kumar A., Hakizimana J.C., Dusangumukiza F., Guo D., Naidu R., Nkinahamira F. "Extractant-immobilized dendritic fibrous nanosilica for rapid and selective rare-earth separation from complex aqueous matrices." Desalination (2026). DOI: 10.1016/j.desal.2026.120583.