Hollow α-Fe2O3 Nanoboxes Derived from Metal–Organic Frameworks and Their Superior Ability for Fast Extraction and Magnetic Separation of Trace Pb2+

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• 作者：Qiaoling Mo ; Jinxin Wei ; Keyi Jiang ; Zanyong Zhuang ; Yan Yu
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2017
• 出版时间：February 6, 2017
• 年：2017
• 卷：5
• 期：2
• 页码：1476-1484
• 全文大小：800K
• ISSN：2168-0485

文摘

Hierarchical metals oxide nanostructure derived from annealing of metal–organic frameworks (MOFs) usually have large particle size and low specific surface area and, as a result their activities, become limited. In this work, we incorporated KMnO<sub>4sub> into Prussian blue (PB) microcubes and obtained Mn-doped α-Fe<sub>2sub>O<sub>3sub> nanoboxes by annealing the complex. We found that KMnO<sub>4sub> stayed inside the pores of the PB framework and restricted the crystal growth of α-Fe<sub>2sub>O<sub>3sub> during annealing. Consequently, the Mn-doped Fe<sub>2sub>O<sub>3sub> nanoboxes have small particle size, large specific area (452 m<sup>2sup>/g), and a significant amount of adsorbed oxygen in the form of OH<sup>–sup> on the surface as determined by X-ray photoelectron spectroscopy. It could serve as an adsorbent to quickly remove the trace-level (40 mg/L) Pb<sup>2+sup> from water. Within 1 min, this nanoadsorbent (0.2 g/L) extracted >70% Pb<sup>2+sup> in the solution, and >91.6% in 15 min. Besides, it also selectively captures Pb<sup>2+sup> (40 mg/L) from a synthetic Pb/Zn mining wastewater containing Zn<sup>2+sup> (40 mg/L) and various kinds of interfering ions (Na<sup>+sup>, K<sup>+sup>, Mg<sup>2+sup>, Ca<sup>2+sup>, SO<sub>4sub><sup>2–sup>, NO<sub>3sub><sup>–sup>, Cl<sup>–sup>). The maximizing capacity of Pb<sup>2+sup> reaches to 900 mg/g when treating concentrated Pb<sup>2+sup> solution (1g/L). The spent adsorbent could be easily retrieved from the solution by magnetic separation. We anticipate the findings here will help to inspire the design of other novel MOFs-derived nanomaterials.