Lanmodulin-Functionalized Magnetic Nanoparticles as a Highly Selective Biosorbent for Recovery of Rare Earth Elements

Recovering rare earth elements (REEs) from waste streams represents a sustainable approach to diversify REE supply while alleviating the environmental burden. However, it remains a critical challenge to selectively separate and concentrate REEs from low-grade waste streams. In this study, we developed a new type of biosorbent by immobilizing Lanmodulin-SpyCatcher (LanMSpycatcher) on the surface of SpyTag-functionalized magnetic nanoparticles (MNPs) for selective separation and recovery of REEs from waste streams. The biosorbent, referred to as MNPLanM, had an adsorption activity of 6.01 +/- 0.11 mu mol-terbium/g-sorbent and fast adsorption kinetics. The adsorbed REEs could be desorbed with >90% efficiency. The MNP-LanM selectively adsorbed REEs in the presence of a broad range of non-REEs. The protein storage stability of the MNP-LanM increased by two-fold compared to free LanM-SpyCatcher. The MNP-LanM could be efficiently separated using a magnet and reused with high stability as it retained similar to 95% of the initial activity after eight adsorption-desorption cycles. Furthermore, the MNP-LanM selectively adsorbed and concentrated REEs from the leachate of coal fly ash and geothermal brine, resulting in 967-fold increase of REE purity. This study provides a scientific basis for developing innovative biosorptive materials for selective and efficient separation and recovery of REEs from low-grade feedstocks.

Automated summary

In this study, a new biosorbent (MNPLanM) was developed by immobilizing Lanmodulin-SpyCatcher on the surface of SpyTag-functionalized magnetic nanoparticles (MNPs) for selective separation and recovery of rare earth elements (REEs) from waste streams. The biosorbent exhibited high adsorption activity and fast kinetics, and the adsorbed REEs could be efficiently desorbed. MNPLanM selectively adsorbed REEs in the presence of non-REEs and showed high stability after multiple adsorption-desorption cycles. Furthermore, MNPLanM effectively concentrated REEs from low-grade feedstocks, achieving a significant increase in REE purity.