Nagasaka Cocoro A, Ogiwara Naoki, Kobayashi Shunsuke, Uchida Sayaka
Department of Basic Science, School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
Nanostructures Research Laboratory, Japan Fine Ceramics Center, Atsuta, Nagoya, 456-8587, Japan.
Small. 2024 Apr;20(17):e2307004. doi: 10.1002/smll.202307004. Epub 2023 Dec 25.
Materials for Cs adsorption continue to be important for the treatment of various solutions. Metal-organic frameworks (MOFs) with large specific surface areas promise adsorption properties for various gases, vapors, and ions. However, the utilization of MOFs for alkali ion capture, specifically, Cs capture is still in its infancy. Herein, MOFs are hybridized with polyoxometalates (POMs) to study the effect of i) MOF type, ii) POM type, and iii) POM loading amounts on Cs capture. In particular, the composite of ZIF-8 and [α-PMoO] (PMo/ZIF-8) adsorbed Cs ions effectively when compared to pristine ZIF-8. In addition, the reduction of Mo within the POM from Mo to Mo by ascorbic acid during the Cs uptake process doubled the Cs uptake capacity of PMo/ZIF-8. This observation can be attributed to the increased overall negative charge of the POM facilitating Cs uptake to compensate for the charge imbalance. Hybridization with other MOFs (MIL-101 and UiO-66) largely suppresses the Cs uptake, highlighting the importance of hydrophobicity in Cs capture. Furthermore, PMo/ZIF-8 led to an outstanding Cs uptake (291.5 mg g) with high selectivity (79.6%) from quinary mixtures of alkali metal cations even among other representative porous materials (Prussian blue and zeolites).
用于铯吸附的材料对于各种溶液的处理仍然很重要。具有大比表面积的金属有机框架（MOF）有望对各种气体、蒸汽和离子具有吸附性能。然而，MOF用于碱金属离子捕获，特别是铯捕获仍处于起步阶段。在此，将MOF与多金属氧酸盐（POM）杂交，以研究i）MOF类型、ii）POM类型和iii）POM负载量对铯捕获的影响。特别是，与原始ZIF-8相比，ZIF-8和[α-PMoO]（PMo/ZIF-8）的复合材料能有效吸附铯离子。此外，在铯吸收过程中，抗坏血酸使POM中的钼从Mo还原为Mo，使PMo/ZIF-8的铯吸收能力提高了一倍。这一现象可归因于POM整体负电荷的增加促进了铯的吸收，以补偿电荷不平衡。与其他MOF（MIL-101和UiO-66）杂交在很大程度上抑制了铯的吸收，突出了疏水性在铯捕获中的重要性。此外，即使在其他代表性多孔材料（普鲁士蓝和沸石）中，PMo/ZIF-8也能从碱金属阳离子的五元混合物中以高选择性（79.6%）实现出色的铯吸收（291.5 mg g）。
