Team:Bonn-Rheinbach/Description

iGEM Bonn 2021

Project Social Outreach Attributions Team

Project

Project Description

With the ongoing advancements made in high technology fields and the resulting growing demand for special resources, the problem of environmentally friendly extraction methods of rare earth elements (REEs) arises. We offer a solution for this problem by presenting a biometallurgic extraction alternative that does not require toxic chelators. In comparison to the strong thermal treatment in conventional REE extraction processes, our biotechnological approach is run at moderate temperatures.

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Our Alternative

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In 2018 the bacterial protein Lanmodulin was first characterized [1]. It possesses unique properties as it is able to bind three atoms from the rare earth elements strongly and highly (see Figure 1) specific at pH>4.0. When the pH gets lowered to <2.5 the protein configuration changes and it releases the bound elements. Moreover, the protein is highly stable and can be subjected to high temperatures (up to 95°C) and extreme pH levels (<1) without denaturing. These properties allow to use it under harsh industrial conditions [2].

Figure 1 Representation of LanM (blue) bound to three REE Ions (cyan) [2]

Figure 2 Comparison of C0₂ emmisions that are created during the production of one kg of copper (0.18 kg [3]) of REEs (14 kg [4])

Current industrial extraction methods rely greatly on synthetic chelators and require huge amounts of energy to separate rare earth elements from the other feedstock components. This results in a carbon footprint of rare earth elements that is almost 100x that of copper [3][4]. We developed a process where the application of Lanmodulin suffices to separate the desired elements from undesired components.

First the feedstock gets acidified to dissolve the REEs. In our case, the applied feedstock are apatite ores. However, different feedstocks, such as E-waste are also viable (see Partnerships or directly iGEM Calgary). Afterwards, LanM is added and binds the REEs. Then, the LanM/REE complex is separated from the rest of the solution and the pH gets lowered, so that the protein releases the REEs. Now, the protein can be separated from the solution to be reused. Only REEs remain in the solution.

Figure 3 Scheme of the general REE extraction process

Steps that require a lot of energy as well as toxic chelators were strongly minimized. That way, the carbon footprint as well as other harmful environmental impacts of rare earth element production can be mitigated. With this project we aim to contribute to a greener and sustainable industry.

written by Alexander Schmatz

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References:
[1] Cotruvo, J. A. et al. (2018) ‘Lanmodulin: A Highly Selective Lanthanide-Binding Protein from a Lanthanide-Utilizing Bacterium’, Journal of the American Chemical Society, 140(44), pp. 15056–15061. doi: 10.1021/jacs.8b09842.
[2] Deblonde, G.J.-P.; Mattocks, J.A.; Park, D.W.; Reed, D.W.; Cotruvo, J.A.; Jiao, Y. (2020): Selective and Efficient Biomacromolecular Extraction of Rare-Earth Elements using Lanmodulin. In Inorganic Chemistry 59: 11855-11867.
[3] Chesnokov, Y. N. et al. (2017) ‘Estimation of CO2-Equivalent Emission under the Copper Fire Refining Process’, IOP Conference Series: Earth and Environmental Science, 72(1). doi: 10.1088/1755-1315/72/1/012013.
[4] Sprecher, B. et al. (2014) ‘Life cycle inventory of the production of rare earths and the subsequent production of NdFeB rare earth permanent magnets’, Environmental Science and Technology, 48(7), pp. 3951–3958. doi: 10.1021/es404596q.