MOF/SOFヘテロ構造体上に銀ナノクラスターを高選択的に固定化し、水溶液からの放射性ヨウ素の効率的吸着を実現

Highly selective anchoring silver nanoclusters on MOF/SOF heterostructured framework for efficient adsorption of radioactive iodine from aqueous solution.

• Hualun Li
• Ye Li
• Bolin Li
• Dongbin Liu
• Yuzhi Zhou

抄録

銀ナノクラスターをMOF/SOFヘテロ構造体(MSHC)に固定化することにより、ヨウ素との結合力が強いAg修飾MOF/SOFヘテロ構造体吸着材(Ag-MSHC)を作製した。6種類の新規Ag-MSHC吸着剤の形態変化プロセスは、Fe, TMA(1,3,5-トリカルボキシベンゼン)及びMA(メラミン)のモル比を調整することで実現でき、最終的にはMOF(金属-有機フレームワーク)とSOF(超分子有機フレームワーク)の組み合わせが得られた。6種類の吸着剤の中で、Ag-MSHC-6はIに対する親和性が非常に高く、Iの最大吸着量は771.6mg/gに達した。これは、Ag-MSHCのトポロジカル構造中のFeの含有量がAg-MSHCへの銀ナノクラスターの取り込みを阻害し、AgOとIの不可逆的な相互作用にさらに影響を与えるためである。さらに、FT-IR, XPS, TGA, SEMを用いて、MSHCとAg-MSHCの微細構造と化学組成を検討し、さらにバッチ吸着実験を行い、Ag-MSHCによるヨウ素吸着性能とそのメカニズムを実証した。このようなMOFとSOFの組み合わせ、銀ナノクラスターの高いドーピング性、ヨウ素との強い結合性を活かして、Ag-MSHCは放射性ヨウ素抽出のための優れた吸着剤と考えられる。

A series of Ag-modified MOF/SOF heterostructured framework adsorbents (Ag-MSHC) with strong binding of iodine were prepared by anchoring silver nanoclusters on MOF/SOF heterostructured framework (MSHC). Morphological transformation process of six novel Ag-MSHC adsorbents can be realized by tailoring the molar ratio of Fe, TMA (1,3,5-Tricarboxybenzen) and MA (melamine), finally resulting in a combination of MOFs (metal-organic frameworks) and SOFs (supramolecular organic framework). Among six adsorbents, Ag-MSHC-6 exhibited an extremely strong affinity towards I, whereas the maximum adsorption capacity of I reaches 771.6 mg/g. An increased tendency of I sorption occurred from Ag-MSHC-1 to Ag-MSCH-6 when the molar ratio of Fe gradually decreased because the content of Fe in topological structure of Ag-MSHC can hinder the incorporation of silver nanoclusters into Ag-MSHC and further influences the irreversible interactions between AgO and I. Besides, FT-IR, XPS, TGA and SEM were used to discuss the microstructures and chemical composition of MSHC and Ag-MSHC, and we also performed batch adsorption experiments to demonstrate the iodine sorption performance and mechanism by Ag-MSHC. Taking advantage of this combination of MOFs and SOFs, high degree of doping of silver nanoclusters as well as its strong binding ability of iodine, Ag-MSHC can be considered as a superior adsorbent for radioactive iodine extraction.

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