高等学校化学学报 ›› 2017, Vol. 38 ›› Issue (8): 1415.doi: 10.7503/cjcu20170036

• 物理化学 • 上一篇    下一篇

负载零价铁膨胀石墨的合成及对水中NO3-去除的效果与机制

徐从斌1,2, 张丽1, 杨文杰3, 孙宏亮3, 刘伟江3, 焦振寰4, 焦春磊1, 林爱军1   

  1. 1. 北京化工大学环境科学与工程系, 北京 100029;
    2. 中国科学院生态环境研究中心, 北京 100085;
    3. 环境保护部环境规划院, 北京 100012;
    4. 北京市昌平区水务局, 北京 102200
  • 收稿日期:2017-01-16 修回日期:2017-07-10 出版日期:2017-08-10 发布日期:2017-07-10
  • 通讯作者: 林爱军,男,博士,副教授,主要从事环境修复材料与技术方面的研究.E-mail:environbiol@mail.buct.edu.cn E-mail:environbiol@mail.buct.edu.cn
  • 基金资助:

    北京化工大学"双一流"建设专项经费(批准号:PY201606)和北京化工大学学科建设发展研究基金(批准号:DCD XK1503)资助.

Nitrate Removal by Expanded Graphite Loaded with Zero-valent Iron:Performance and Mechanism

XU Congbin1,2, ZHANG Li1, YANG Wenjie3, SUN Hongliang3, LIU Weijiang3, JIAO Zhenhuan4, JIAO Chunlei1, LIN Aijun1   

  1. 1. Department of Eviromental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China;
    2. Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;
    3. Chinese Academy for Environmental Planning, Beijing 100012, China;
    4. Beijing Changping Water Authority, Beijing 102200, China
  • Received:2017-01-16 Revised:2017-07-10 Online:2017-08-10 Published:2017-07-10
  • Supported by:

    Supported by the Higher Education and High-quality and World-class Universities, China(No.PY201606) and BUCT Fund for Disciplines Construction and Development, China(No.DCDXK1503).

摘要:

以网络状孔型结构发达的膨胀石墨(EG)为载体,采用化学沉积法制备了负载零价铁(ZVI)的膨胀石墨(EG-ZVI).利用扫描电子显微镜(SEM)、X射线衍射(XRD)仪及X射线光电子能谱仪(XPS)等对负载及反应前后的EG-ZVI进行表征,探究了EG-ZVI对硝酸根(NO3-)的去除效果并对其反应产物及机理进行了分析.结果表明,亚微米级零价铁已负载到EG石墨表面,且分布均匀;与EG相比,EG-ZVI对NO3-的去除能力显著提升,其去除率是EG的2.3倍.得益于铁碳原电池效应,EG-ZVI对pH依赖性比零价铁低,即使在pH=9的条件下,NO3-去除率依然能达到65%以上,是单独用零价铁处理时的1.83倍;EG-ZVI去除NO3-是吸附和还原过程共同作用的结果,符合三级动力学模型,其还原过程由负载在EG表面的零价铁发生腐蚀提供电子,从而还原NO3-产生以NH4+-N为主的含氮化合物;EG-ZVI对NO3-具有较强的还原吸附作用,并能解决零价铁在反应过程中生成惰性层或金属氢氧化物导致去除效率低的缺陷,使其在含NO3-废水的处理中具有较高的应用潜力.

关键词: 零价铁, 膨胀石墨, 硝酸根去除, 去除机理

Abstract:

Zero-valent iron(ZVI) loaded onto expanded graphite(EG) as a composite material(EG-ZVI) was prepared through chemical deposition method to remove nitrate. The EG/ZVI was characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). It is observed that the EG was successfully loaded with sub-micron scale zero-valent iron. Batch experiments with variable theoretical ZVI mass loading, pH values and temperature were conducted to evaluate the removal performance of EG-ZVI. The results showed that the removal rate of nitrate was 2.3 times higher than that for EG. Furthermore, the removal of nitrate by EG-ZVI shows little dependence on solution pH. Even at pH=9, the nitrate removal efficiency could attain 65% after reaction for 90 min. Galvanic cell effect and high specific surface area are the main reasons for the enhanced removal of nitrate by EG-ZVI with chemical reduction and physical adsorption. And third-order kinetic model is well fitted. XPS were used to analyze the mechanisms of nitrate removal, which indicated that ZVI loaded on the surface was oxidized, and the removed nitrate was reduced to NH4+-N and NO2--N. In addition, EG-ZVI could overcome the shortcomings of ZVI which formed undesirable precipitation of ferrous hydroxide on the surface during reaction frequently. High removal capability, excellent stability and broad applicability make EG-ZVI ideal candidates for nitrate removal in practical application.

Key words: Zero-valent iron, Expanded graphite, NO3- removal, Removal mechanism

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