Written by: Prof. Dr. Dipl.-Ing. Huayna Terraschke
Rare earth elements (REEs) are indispensable to many of the technologies shaping a sustainable and technologically advanced future. Electric vehicles, wind turbines, energy-saving light-emitting diodes (LEDs), high-performance magnets, computers, and numerous other applications depend on their unique chemical, magnetic, and optical properties. [1-3] Neodymium and dysprosium are particularly important components of NdFeB permanent magnets, which enable highly efficient electric motors and wind-power generators. As the global transition away from fossil fuels accelerates, demand for REEs is expected to increase dramatically, potentially reaching seven times today’s level by 2040. [4] (opens in a new tab)
Why Rare Earths Matter?
The growing importance of REEs is accompanied by an increasingly vulnerable supply chain. Dysprosium provides a striking example. Its name originates from the Greek dysprositos, meaning “hard to obtain,” and its production has increased from approximately 135–185 tonnes of dysprosium oxide annually in the early 1990s to around 2,000–3,000 tonnes in the 2020s. At the same time, resources, refining capacities, and technological expertise remain geographically concentrated. Approximately 90% of global rare earth refining and processing capacity is concentrated in a single country, while tighter export licensing frameworks introduced in 2025 have further highlighted the strategic risks associated with this dependence. [5-6]
Highlights
- REEs are essential for electric mobility, smartphones, laptops, renewable energy, and advanced materials.
- Demand for REEs could increase dramatically in the coming decades.
- Dysprosium is critical for high-performance permanent magnets.
- Global refining and processing capacities remain highly concentrated.
- Supply security therefore requires alternatives to conventional primary production.
Why Rare Earth Recycling Is Becoming Essential?
Developing reliable approaches for recovering REEs from secondary resources is no longer only an environmental objective. It is an economic, technological, and geopolitical necessity. Recycling can provide an important alternative source of these critical elements while reducing dependence on primary mining and geographically concentrated supply chains.
The potential is considerable. Secondary resources such as energy-saving lamps, electronic devices, and other waste streams can contain REE concentrations many times higher than those found in natural ores—up to 17 times higher in some applications. At the same time, recycling can reduce the environmental impacts associated with mining and help avoid some of the radioactive byproducts that can accompany the processing of REE-containing ores. [4,5]
Yet despite this enormous potential, the global recycling rate for rare earth elements remains remarkably low, at approximately 1%. [5,7] The fundamental reason is not simply a lack of recycling technologies. One of the central obstacles is the chemistry of the rare earth elements themselves.
From Critical Resources to Sustainable Technologies
The challenge posed by rare earth elements extends far beyond mining. Securing future supplies will require a fundamental transformation in the way these elements are sourced, separated, recovered, and reused. Recycling will become increasingly important as demand grows and easily accessible primary resources remain subject to environmental, economic, and geopolitical constraints. [4-7]
But successful recycling will require more than simply collecting REE-containing waste. The central scientific challenge is to selectively recover valuable elements from highly complex mixtures—and, where necessary, to separate chemically similar neighboring lanthanides with high efficiency and low environmental impact.
This is fundamentally a chemistry problem.
Why Are Rare Earths So Difficult to Separate?
The lanthanides are among the most chemically similar elements in the periodic table. Most occur predominantly in the +3 oxidation state, while their valence 4f orbitals are shielded by outer electron shells and therefore contribute only minimally to chemical bonding. Further, neighboring lanthanides differ in ionic radius by only about 0.01 Å, a steady decrease known as the lanthanide contraction. These apparently small differences translate into similar complex-formation constants, salt solubilities, and solvent-extraction distribution coefficients. [8] (opens in a new tab)
The Separation Challenge
Conventional extraction processes exploit subtle differences in chemical properties between neighboring REEs. Because these differences are often extremely small, industrial processes may require long cascades containing numerous individual extraction stages.
Such processes can be highly effective, but they can also be technically complex, capital-intensive, and energy-intensive. They may additionally generate substantial quantities of wastewater and chemical waste. [9] (opens in a new tab)
Beyond Trial and Error: Why Fundamental Chemistry Matters?
The complexity of rare earth separation demonstrates why future recycling technologies cannot be developed efficiently through trial and error alone.
Selective recovery requires an understanding of why a particular chemical process works. The behavior of a rare earth ion is governed by a complex interplay of fundamental parameters, including ionic radius, hydration, coordination chemistry, ligand structure and rigidity, pH, counter-ion effects, hard–soft, acid–base interactions, solubility equilibria, and interfacial phenomena. [10-11]
These principles are particularly important for developing technologies capable of recovering REEs from increasingly complex secondary resources and, ultimately, for separating individual rare earth elements from one another.
The objective is therefore not simply to develop another recycling process. It is to establish a predictive chemical framework that allows efficient and selective processes to be designed rationally.
The Missing Link: Education in Rare Earth Chemistry
Despite the strategic importance of REEs, advanced and structured education in rare earth chemistry remains relatively uncommon in many Bachelor’s and Master’s programs worldwide. This creates a growing shortage of specialists who can connect fundamental chemical principles with practical technologies for resource recovery, separation, and recycling.
Addressing this knowledge gap is essential. The scientists developing future recycling technologies need more than an understanding of individual analytical or separation techniques. They need to understand the fundamental chemistry that determines why those techniques work—and when they will fail.
Study Rare Earth Chemistry in Germany in an International Research Environment
The International Master’s program in Chemistry at Kiel University in Germany provides an opportunity to develop precisely this combination of fundamental knowledge and practical research experience. Taught in English and embedded in a strong research environment, the program provides students with a comprehensive understanding of the chemical and physical properties of elements and materials, while connecting this knowledge with areas such as rare earth chemistry, sustainable chemistry, and the hands-on synthesis of rare-earth-containing functional materials as well as their recycling.
Within the research group of Prof. Dr. Huayna Terraschke (opens in a new tab), students can complement their theoretical education with practical laboratory experience and research projects addressing emerging challenges in rare earth chemistry. Master’s theses and research projects can focus on topics including the recovery, separation, and recycling of rare earth elements from spent devices and other secondary resources.
Why Study Rare Earth Chemistry at Kiel University?
Students interested in this field can combine:
- fundamental inorganic and coordination chemistry;
- rare earth chemistry;
- sustainable chemistry;
- materials chemistry;
- experimental laboratory training;
- synthesis and characterization of functional materials;
- research on rare earth recovery, separation, and recycling; and
- an international, English-taught Master's education.
This combination is particularly valuable because the future of rare earth recycling will depend on scientists capable of moving seamlessly between fundamental chemistry and technological application.
International Chemistry Master Program application link: Apply here (opens in a new tab)
References and Literature Recommendation
| [1] | H. Terraschke (Ed). Nanostructured Materials: Applications, Synthesis and In-Situ Characterization. De Gruyter Press, Berlin (2024). ISBN 978-3-11-045829-9 (opens in a new tab). |
| [2] | H. Terraschke, C. Wickleder. UV, Blue, Green, Yellow, Red and Small: Newest Developments on Eu²⁺-doped Nanophosphors. Chemical Reviews 115, 11352 (2015). DOI: 10.1021/acs.chemrev.5b00223 (opens in a new tab) |
| [3] | E. E. S. Teotonio, G. Doungmo, J. Ströh, D. Mustafa, I. F. Costa, H. F. Brito, A. Kotlov, H. Terraschke. In situ and ex situ luminescence investigation of rare earth layered double hydroxides intercalated with mellitate anion. Advanced Optical Materials 13 (2025) 2402187/1. DOI: 10.1002/adom.202402187 (opens in a new tab) |
| [4] | M. A. Perrin, P. Dutheil, M. Wörle, V. Mougel. Recovery of Europium from E-waste Using Redox Active Tetrathiotungstate Ligands. Nat. Commun. 15 (2024) 4577. DOI: 10.1038/s41467-024-48733-z (opens in a new tab) |
| [5] | E. Rudnik. Advances in Dysprosium Recovery from Secondary Sources: A Review of Hydrometallurgical, Biohydrometallurgical and Solvometallurgical Approaches. Molecules 31 (2026) 176. DOI: 10.3390/molecules31010176 (opens in a new tab) |
| [6] | S. Park, C. L. Tracy, R. C. Ewing. Reimagining US Rare Earth Production: Domestic Failures and the Decline of US Rare Earth Production Dominance – Lessons Learned and Recommendations. Resour. Policy 85 (2023) 104022. DOI: 10.1016/j.resourpol.2023.104022 (opens in a new tab) |
| [7] | B. Swain. Challenges and Opportunities for Sustainable Valorization of Rare Earth Metals from Anthropogenic Waste. Rev. Environ. Sci. Biotechnol. 22 (2023) 133. DOI: 10.1007/s11157-023-09647-2 (opens in a new tab) |
| [8] | X. Yin, Y. Wang, X. Bai, Y. Wang, L. Chen, C. Xiao, J. Diwu, S. Du, Z. Chai, T. E. Albrecht-Schmitt, S. Wang. Rare Earth Separations by Selective Borate Crystallization, Nat. Commun. 8 (2017) 14438. DOI: 10.1038/ncomms14438 (opens in a new tab) |
| [9] | D. Talan, Q. Huang. A review of environmental aspect of rare earth element extraction processes and solution purification techniques. Miner. Eng. 179 (2022) 107430. DOI: 10.1016/j.mineng.2022.107430 (opens in a new tab) |
| [10] | B. Ghosh, H. Vapnik, H.-E. Kim, Y. Kim, R. Birawat, Y. Lu, X. Su, H. Yang. Electrochemical Separation and Clean Energy Applications of Rare Earth Elements, Chem. Rev. 125 (2025) 7965. DOI: 10.1021/acs.chemrev.5c00103 (opens in a new tab) |
| [11] | R. F. Higgins; K. P. Ruoff; A. Kumar; E. J. Schelter. Coordination Chemistry-Driven Approaches to Rare Earth Element Separations, Acc. Chem. Res. 55 (2022) 2616. DOI: 10.1021/acs.accounts.2c00312 (opens in a new tab) |
