Acta Chim. Sinica ›› 2018, Vol. 76 ›› Issue (6): 467-474.DOI: 10.6023/A18020069 Previous Articles     Next Articles

Article

石墨毡载纳米δ-MnO2高性能除铵净水材料研究

孙梦佳a, 吴天怡a, 李天玉b, 郭风巧c, 唐阳a, 莫恒亮b, 杨志涛b, 万平玉a   

  1. a 北京化工大学电化学研究所 北京 100029;
    b 北京碧水源膜科技有限公司 北京 101400;
    c 中国城市规划设计研究院水质安全研究所 北京 100044
  • 收稿日期:2018-02-10 出版日期:2018-06-15 发布日期:2018-04-03
  • 通讯作者: 万平玉,E-mail:pywan@mail.buct.edu.cn;Tel.:010-64435452;Fax:010-64435452 E-mail:pywan@mail.buct.edu.cn
  • 基金资助:

    国家自然科学基金(No.21506010)和北京市自然科学基金(No.2182050)资助项目.

Research on High Performance Ammonium Removal Materials Based on δ-MnO2 Nanoplate Arrays Decorated Graphite Felt

Sun Mengjiaa, Wu Tianyia, Li Tianyub, Guo Fengqiaoc, Tang Yanga, Mo Hengliangb, Yang Zhitaob, Wan Pingyua   

  1. a Institute of Applied Electrochemistry, Beijing University of Chemical Technology, Beijing 100029;
    b Beijing OriginWater Membrane Technology Co., Ltd., Beijing 101400;
    c China Academy of Urban Planning & Design, Beijing 100044
  • Received:2018-02-10 Online:2018-06-15 Published:2018-04-03
  • Contact: 10.6023/A18020069 E-mail:pywan@mail.buct.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 21506010) and the Beijing Natural Science Foundation (No. 2182050).

We synthesized three kinds of MnO2 powder with different crystalline phases including α-MnO2 nanoflowers, β-MnO2 nanorods and δ-MnO2 micro-particles. The structure and morphology of prepared MnO2 were studied by XRD (X-ray diffraction), SEM (Scanning Electron Microscope), TEM (Transmission Electron Microscope) and XPS (X-ray photoelectron spectroscopy), systematically. Adsorption process was conducted in NH4Cl solution (40 mg·L-1 NH3-N) and actual water samples containing NH4+, Ca2+, Mg2+, K+ and Na+, respectively. The results demonstrate that δ-MnO2 with 7.2 Å interlayer spacing which is a little larger than the diameter of hydrated ammonium (6.62 Å) has high adsorption capacity; α-MnO2 with[2×2] tunnel of 4.6 Å has less adsorption capacity than that of δ-MnO2, and β-MnO2 whose[1×1] tunnel is just 1.89 Å, barely has adsorption capacity. Then MnO2NPs/GF (MnO2 nanoplates decorated graphite felt) was prepared via a facile in-situ redox process. Graphite felt (GF) was immersed in KMnO4 solution (4 g·L-1, pH=2) at 65℃ for 5 h to get MnO2NPs/GF. GF not only reacted as the reductant of KMnO4, but also acted as 3D framework to support the in-situ deposited MnO2NPs. MnO2NPs/GF shows high adsorption capacity (15 mg·g-1) and good selectivity (86.7%). In repetitive adsorption-desorption experiments, MnO2NPs/GF not only exhibits good stability after 20 cycles, but also decreases the concentration of NH3-N to as low as 1 mg·L-1. The thermodynamics experiment demonstrates that the adsorption isotherm fit well with Langmuir isotherm, and the adsorption process corresponds to the pseudo-second-order model. The excellent performance of MnO2NPs/GF is attributed to the following three aspects. Firstly, the 7.2 Å interlayer spacing of δ-MnO2 is suitable for the exchange-adsorption of NH4+. Secondly, the ultra-thin MnO2 nanoplate arrays, which vertically grow on the graphite felt substrate, provide fast path and convenient interface for ion exchange. Finally, the interlaced nanoplates with self-supported structure ensure its high stability. In a conclusion, MnO2NPs/GF has a bright future in the field of ammonium removal.

Key words: δ-manganese dioxide nanoplates, removal of ammonium, adsorption materials, adsorption kinetics