化学学报 ›› 2018, Vol. 76 ›› Issue (6): 467-474.DOI: 10.6023/A18020069 上一篇    下一篇

研究论文

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).

首先制备了α-MnO2纳米花簇、β-MnO2纳米针和δ-MnO2微米颗粒三种不同晶型的MnO2粉末材料,对其结构、形貌及吸附除铵能力进行了表征和测试.结果表明,层间距(7.2Å)大于NH4+直径(2.96Å)和水合NH4+直径(6.62Å)的δ-MnO2相比其他两种晶型的MnO2有更高的NH4+吸附量;接着研究采用KMnO4原位氧化还原法在石墨毡(GF)上直接生长超薄δ-MnO2纳米片(MnO2NPs)阵列构筑了石墨毡载纳米MnO2(MnO2NPs/GF)多级结构材料,制备简单,无须成型造粒就可直接用作除铵净水材料,研究结果表明,MnO2NPs/GF不仅具有较高的吸附量(15 mg·g-1)与良好的选择性,同时还展现了优异的快速吸附和稳定的循环使用性能.MnO2NPs/GF对水中NH4+的吸附符合准二级动力学模型,其吸附等温线符合Langmuir吸附等温式,是吸附-离子交换法除铵的理想材料.

关键词: 纳米δ-MnO2, 除铵净水, 吸附材料, 吸附动力学

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