Superfund Research Program

November 2022

Hot Publication

Researchers from the University of New Mexico (UNM) SRP Center reported on a series of experiments to optimize specialized materials that can remove uranium from water and better understand the mechanisms behind how they work. The UNM SRP Center focuses on understanding and reducing exposures to members of the Navajo Nation living near abandoned uranium mines. 

The team looked at polymer sorbent materials made with nanofibers, which give them a high surface area and porosity, and added phosphonate functionalized groups. These functional groups help to bind uranium over a wide range of pH in the environment.

First, they tested which materials removed the most uranium from the water and found that phosphonate groups with longer alkyl chains performed best. The researchers attributed this to the fact that longer chains are better integrated and retained within the material, which create sites for uranium to bind.

Next, they sought to understand how realistic environmental conditions in water — specifically the presence of minerals calcium and carbonate — affect uranium uptake. They found that both calcium and carbonate reduced the ability of the sorbent to take up uranium, which they suggested may be related to interactions with the minerals that change the oxidation state of uranium in water.

Finally, they explored the mechanism by which the functionalized materials bound uranium. The team reported that uranium largely bound to phosphonate with a negative surface charge, and that the presence of minerals may influence uranium uptake by shifting its charge from positive to negative, making it repel from the polymer rather than bind to it.

According to the researchers, these findings will help in designing materials that are even better suited for detecting and removing uranium from water.

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