An XAFS study of Cs adsorption by the precipitation bands of Mn-Fe-based Prussian blue analogues spontaneously formed in agarose gel
An XAFS study of Cs adsorption by the precipitation bands of Mn-Fe-based Prussian blue analogues spontaneously formed in agarose gel
复制标题
DOI：
10.1039/c9cp03661j
复制
发表时间：
2019-10-28
影响因子：
3.3
通讯作者：
Abe, Hitoshi
中科院分区：
文献类型：
--
作者：
Hayashi, Hisashi;Aoki, Saya;Abe, Hitoshi
用X射线吸收精细结构谱结合扫描电镜（SEM）和X射线荧光（XRF）分析研究了Mn-Fe基普鲁士蓝类似物（Mn-FePBA）在琼脂糖凝胶中自发形成的沉淀带对Cs+的吸附。通过将含有0.05 M [Fe（CN）（6）]（3-）和2.3质量%琼脂糖的凝胶与0.50 M MnSO 4溶液接触来制备两个凝胶样品，向其中一个溶液中引入0.10 M CsCl溶液。SEM图像和XRF强度分布显示Mn-Fe PBA形成立方微晶（约100 μ m）。3 × 3 × 3 μ m的大小）的凝胶，捕获Cs+离子具有相当高的亲和力。Cs的L-3边和Mn的K边X射线吸收近边结构（XANES）光谱，这是与FEFF模拟的帮助下进行分析，强烈表明，Cs吸附发生在相对较大的缺陷位置接近的子立方体面临的PBA。这一建议得到了Cs L-3边扩展X射线吸收精细结构光谱的支持，该光谱表明Cs+离子周围的第一和第二配位壳层分别位于0.35 +/- 0.02 nm的Cs-O距离和0.43 +/- 0.01 nm的Cs-N距离处，配位数为1.5 +/-0.5和3.0 +/-0.5。Mn K边XANES数据还表明，H2O分子，最初占据许多立方中心的Mn-Fe PBAs，主要是取代Cs吸附过程中。这些研究结果提供了有价值的见解，充分了解铯吸附Mn-Fe PBA。
The adsorption of Cs+ ions by the precipitation bands of a Mn-Fe based Prussian blue analogue (Mn-Fe PBA) that form spontaneously in agarose gel was investigated by X-ray absorption fine structure spectroscopy coupled with scanning electron microscopy (SEM) and X-ray fluorescence (XRF) distribution analysis. Two gel samples were prepared by contacting a gel containing 0.05 M [Fe(CN)(6)](3-) and 2.3 mass% agarose with a 0.50 M MnSO4 solution, into one of which a 0.10 M CsCl solution was introduced. The SEM images and the XRF intensity distributions reveal that Mn-Fe PBA forms cubic crystallites (approx. 3 x 3 x 3 mu m in size) in the gels that trap Cs+ ions with considerably high affinity. Cs L-3-edge and Mn K-edge X-ray absorption near-edge structure (XANES) spectra, which were analyzed with the aid of FEFF simulations, strongly suggest that Cs adsorption occurs at relatively large defect sites close to the sub-cube faces in the PBA. This suggestion is supported by Cs L-3-edge extended X-ray absorption fine structure spectroscopy, which suggested that the first and second coordination shells around the Cs+ ions are at a Cs-O distance of 0.35 +/- 0.02 nm and a Cs-N distance of 0.43 +/- 0.01 nm, respectively, with coordination numbers of 1.5 +/- 0.5 and 3.0 +/- 0.5. The Mn K-edge XANES data also suggest that H2O molecules, which initially occupy many cubic centers in the Mn-Fe PBAs, are mostly displaced during Cs adsorption. These findings provide valuable insight toward fully understanding Cs adsorption by Mn-Fe PBA.