A groundbreaking discovery: eggshell waste can recover rare earth elements needed for green energy

A collaborative team of researchers has made a groundbreaking discovery with the potential to have a significant impact on the sustainable recovery of rare earth elements (REEs), which are increasingly in demand for use in green energy technologies. The team found that simple eggshell waste could recover REES from water, providing a new, environmentally friendly method for its extraction.

The researchers from Trinity College Dublin’s School of Natural Sciences and iCRAG, the Ireland Research Center in Applied Geosciences, have just published their findings in the journal ACS Omega.

There is increasing demand for REEs, which are essential for the technologies used in electric cars and wind turbines, for example, but there is a relatively limited supply. As a result, scientists must find new ways to extract them from the environment – ​​and in sustainable ways, where current methods are often harmful.

Here, the researchers discovered that calcium carbonate (calcite) in eggshells can effectively absorb and separate these valuable REEs from water.

The researchers placed eggshells in solutions containing REEs at different temperatures, from a pleasant 25°C to a scorching 205°C, and for different periods of time up to three months. They found that the elements could enter the eggshells via diffusion along the calcite boundaries and organic matrix, and that at higher temperatures the rare earth built new minerals on the eggshell surface.

At 90°C, the surface of the eggshell helped restore formations of a rare earth compound called kozoite. As temperatures warmed, the eggshells underwent a complete transformation, with the calcite shells dissolving and being replaced by polycrystalline kozoite. And at the highest temperature of 205°C, this mineral gradually turned into bastnasite, the stable rare earth carbonate mineral used by industry to extract REEs for technological applications.

This innovative method suggests that discarded eggshells can be reused as a low-cost, environmentally friendly material to meet the growing demand for REES, because the eggshells retain several rare earth metals in their structure over time.

Lead author Dr. Remi Rateau says: “This study presents a potentially innovative use of waste material that not only provides a sustainable solution to the problem of rare earth metal recovery, but also aligns with the principles of the circular economy and waste valorization.”

Lead researcher Prof. Juan Diego Rodriguez-Blanco highlighted the wider implications of the findings, adding: “By converting eggshell waste into a valuable resource for rare earth recovery, we address critical environmental issues associated with traditional extraction methods and contribute we contribute to the development of greener technologies.”