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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2026-06-11 23:58 |
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Conference: Bucharest University Faculty of Physics 2026 Meeting
Section: Physics and Technology of Renewable and Alternative Energy Sources
Title:
Microbial Electro-Refining of REEs: Electroactive Bacterial Biofilms for Selective Lanthanide Recovery
Authors:
Matei-Tom IACOB (1,2), Cornelia DIAC (1), Bogdan Ciprian MITREA (1,2), Sermon CAISAR (2), Cornelia NICHITA (1,3), Adriana BĂLAN (1,2), Ioan STAMATIN (1,2)
*
Affiliation:
1) University of Bucharest, Faculty of Physics, 3Nano-SAE Reasearch Centre, Magurele, PO Box MG 38, 077125, Romania
2) University of Bucharest, Faculty of Physics, Magurele, PO Box MG 38, 077125 Romania
3) National Institute for Chemical – Pharmaceutical Research and Development, 112 Vitan Avenue, 031299, Bucharest, Romania.
E-mail
tom.iacob@3nanosae.org
Keywords:
Rare Earth Elements, Lanthanides, Bioelectrochemical recovery, Microbial electro-refining, Extracellular electron transfer, Biofilm electrode
Abstract:
Rare Earth Elements (REEs) are critical for producing high-performance permanent magnets in electric vehicles, wind turbines, and advanced electronics. Traditional hydrometallurgical refining from ores like bastnäsite or monazite is chemically demanding, energy-intensive, and produces substantial hazardous waste streams.
Although bioelectrochemical systems have been explored for recovering various metals, their use for lanthanide separation and refining is still in its early stages. A key obstacle is the close chemical similarity of trivalent lanthanide ions; their nearly identical ionic radii and overlapping reduction behaviors make selective recovery difficult. Many of these elements can also exhibit toxicity toward microbial communities, which further complicates the development of robust biological processes.
Building on recent advances in microbial metal reduction, we outline a bioelectrochemical framework that leverages the extracellular electron transfer capabilities of Shewanella oneidensis MR-1 (and potentially Geobacter sulfurreducens) to process solubilized lanthanide streams. Inspired by approaches where bacterial biofilms on electrodes are coupled to a low-voltage external power source, the system uses electroactive bacteria immobilized on conductive electrodes to facilitate the reduction and recovery of REE ions.
In this setup, the biofilm-decorated electrodes are connected to a modest external voltage (similar to a simple battery-driven configuration), enabling the bacteria to mediate electron transfer to adsorbed lanthanide species without the need for organic electron donors. This can promote the formation of reduced lanthanide species or nanoparticles, particularly for elements like europium that are more readily reducible (Eu³⁺ → Eu²⁺). For other lanthanides, the localized microenvironment created by microbial activity may support controlled precipitation based on subtle differences in solubility.
The self-regenerating nature of the bacterial outer-membrane cytochromes appears to help the biofilm tolerate metal exposure better than planktonic cells, maintaining activity under conditions that would otherwise be challenging. Compared with conventional solvent extraction or chemical precipitation methods, this strategy could significantly reduce reliance on aggressive reagents and lower the overall environmental footprint.
References:
Maes, S., Zhuang, W.-Q., Rabaey, K., Alvarez-Cohen, L., & Hennebel, T. (2017). Concomitant leaching and electrochemical extraction of rare earth elements from monazite. Environmental Science & Technology, 51(3), 1654–1661. https://doi.org/10.1021/acs.est.6b03675
Macaskie, L. E., Moriyama, S., Mikheenko, I., Singh, S., & Murray, A. J. (2017). Biotechnology processes for scalable, selective rare earth element recovery. In J. E. A. Orjuela (Ed.), Rare earth element. IntechOpen. https://doi.org/10.5772/intechopen.68429
Iacob, M. T., Ghinea, A., Moroşanu, A.-M., Ardelean, I., Stamatin, Ş. N., & Moisescu, C. (2026). Batteries to the rescue: The formation of Pt bioelectrocatalysts with Shewanella oneidensis MR-1 and commercial batteries. RSC Applied Interfaces, 3(1), 61–68. https://doi.org/10.1039/D5LF00223K
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