The groundbreaking discovery of using eggshell waste to recover rare earth elements (REEs) from water presents a tremendous opportunity to meet the growing demand for REEs in green energy technologies.
This environmentally friendly method, as published by researchers from Trinity’s School of Natural Sciences and iCRAG in the international journal ACS Omega, offers a sustainable solution to the current scarcity of REEs.
With the increasing demand for REEs in technologies like electric cars and wind turbines, finding new extraction methods that are both effective and eco-friendly is crucial for a sustainable future.
The researchers discovered that calcium carbonate (calcite) in eggshells can effectively absorb and extract valuable rare earth elements (REEs) from water. By placing eggshells in REE solutions at different temperatures for varying time periods, the elements could be absorbed into the eggshells and used to form rare earth compounds.
The researchers conducted experiments involving eggshells immersed in solutions containing REEs at temperatures ranging from 25 °C to 205 °C and for varying durations up to three months. Their findings revealed that the elements could permeate the eggshells through diffusion along the calcite boundaries and the organic matrix. Moreover, at higher temperatures, the rare earth elements formed new minerals on the surface of the eggshells.
At 90 °C, the eggshell surface formed a rare earth compound known as kozoite. As the temperature increased, the eggshells underwent a remarkable transformation, with the calcite shells dissolving and being replaced by polycrystalline kozoite.
At a maximum temperature of 205°C, this mineral undergoes a gradual transformation into bastnasite, the stable rare earth carbonate mineral essential for extracting REEs for various technological applications.
This groundbreaking approach indicates that waste eggshells have the potential to be repurposed as a cost-effective, environmentally friendly material to address the rising demand for REEs. This is because eggshells gradually accumulate unique rare earths within their structure, making them a valuable resource.
“This study presents a potential innovative use of waste material that not only offers a sustainable solution to the problem of rare earth element recovery but also aligns with the principles of circular economy and waste valorization,” said lead author Dr. Remi Rateau commented on the significance of the research.
“By transforming eggshell waste into a valuable resource for rare earth recovery, we address critical environmental concerns associated with traditional extraction methods and contribute to the development of greener technologies,” adds Prof. Juan Diego Rodriguez-Blanco, emphasizing the broader implications of the findings.
Journal reference:
- Rémi Rateau, Melanie Maddin, Adrienn M. Szucs, Luca Terribili, Kerstin Drost, Paul C. Guyett, and Juan Diego Rodriguez-Blanco. Utilization of Eggshell Waste Calcite as a Sorbent for Rare Earth Element Recovery. ACS Omega, 2024; DOI: 10.1021/acsomega.4c00931