Oyster Shells Recover Rare Earth Metals & Clean Polluted Water

Scientists at Trinity College Dublin have discovered a new method of purifying contaminated water that can also sustainably extract rare earth elements (REEs).

Their research found that oyster shells, along with mussel and cockle shells, can naturally remove REE from contaminated water by transforming dissolved metals into stable mineral crystals.

Dr. Juan Diego Rodriguez-Blanco, Principal Investigator of the project, said:

"What makes this discovery particularly promising is that the process is entirely mineral-driven. The shells naturally transform dissolved rare earth elements into new solid minerals, so this is not a process that requires much financial outlay or technical equipment."

The team collected shells of oysters, mussels, and cockles from beaches around Dublin. They cleaned, crushed, and exposed them to solutions that contained rare earth metals such as dysprosium, neodymium, and lanthanum.

While submerged, the shells' calcium carbonate structure dissolved, as new rare earth carbonate minerals formed. This process showed how the shells exchanged their original minerals for REEs.

Among all the shell types tested, oyster shells delivered the strongest performance.

Mussel and cockle shells choke off absorption by forming mineral barriers, but oyster shells keep the reaction going. The layered, porous structure of oyster shells remains permeable, which allows the transformation to penetrate the entire shell.

Under certain laboratory conditions, oyster shells were completely transformed within a week.

Even more impressive was the amount of material they captured. The oyster shells absorbed up to 1.5 grams of rare earth metals per gram of shell, meaning they could trap more metal than their own weight.

The study also showed that various REEs were absorbed at different stages of the reaction. Neodymium tended to be captured earlier, while lanthanum and dysprosium were incorporated later in the process.

According to Dr. Rodriguez-Blanco, "such processes could potentially be used for environmentally friendly rare earth separation technologies in the future".

Researchers also noted that future real-world applications may not require the same intensive shell preparation used in laboratory testing. Weathered or coarser shells may still perform effectively, potentially further lowering costs and energy requirements.

Read the full article here for more details.

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