School of Civil and Environmental Engineering, University of Technology Sydney (UTS), City Campus, Broadway, NSW, 2007, Australia.
Chemosphere. 2024 Sep;364:143272. doi: 10.1016/j.chemosphere.2024.143272. Epub 2024 Sep 5.
Rare-earth elements (REEs) play a crucial role in state-of-the-art technologies and sustainable energy generation. However, conventional production methods of REE often instigate detrimental impacts on environment. Hence, the development of efficient and sustainable hydrometallurgical methods for REE recovery from complex solution has become a crucial research focus. This study investigates a mixed-matrix membrane composed of a highly europium selective metal-organic framework-based adsorbent, Cr-MIL-PMIDA, embedded in sulfonated poly(ether ketone) (SPEK) polymer membrane matrix to preferentially concentrate europium (Eu) ions in the presence of other competing cations. The activated membrane notably reduced ionic conductivity for Eu compared to other multivalent ions. Membrane extraction experiments further confirmed the selective behavior, demonstrating slower diffusion for Eu compared to Mg and Zn cations. Especially, at pH 5, Mg⁺ and Zn⁺ recovery was greater than 30%, whereas Eu³⁺ recovery remained lower than 4%. We propose that the strong chemical affinity between the phosphate group and Eu help partition of the Eu ions in the membrane phase and inhibit the diffusion and further partitioning of the Eu ion from bulk solution. Furthermore, we demonstrate the stability of the composite membrane and the embedded MOF particles in aqueous solution for up to 12 days without degradation, attributing it to the robust chemical stability of the MOF structure.
稀土元素（REEs）在现代技术和可持续能源生产中发挥着至关重要的作用。然而，传统的 REE 生产方法往往会对环境造成不利影响。因此，开发从复杂溶液中高效、可持续地回收 REE 的水冶方法已成为一个关键的研究重点。本研究制备了一种混合基质膜，该膜由高度选择性的含铕金属-有机骨架吸附剂 Cr-MIL-PMIDA 嵌入磺化聚醚醚酮（SPEK）聚合物膜基质中，以在存在其他竞争阳离子的情况下优先浓缩铕（Eu）离子。与其他多价离子相比，活化膜显著降低了 Eu 的离子电导率。膜萃取实验进一步证实了选择性行为，表明 Eu 的扩散速度比 Mg 和 Zn 阳离子慢。特别是在 pH 值为 5 时，Mg⁺和 Zn⁺的回收率大于 30%，而 Eu³⁺的回收率仍低于 4%。我们提出，磷酸基团与 Eu 之间的强化学亲和力有助于将 Eu 离子分配到膜相中，并抑制 Eu 离子从主体溶液中的扩散和进一步分配。此外，我们证明了复合膜和嵌入的 MOF 颗粒在水溶液中的稳定性长达 12 天而没有降解，这归因于 MOF 结构的强大化学稳定性。
