| 题名 | 特殊形貌羟基铁的制备及对水中砷和硒的吸附性能研究 |
| 作者 | 王思达 |
| 学位类别 | 硕士 |
| 答辩日期 | 2016-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘会娟 |
| 关键词 | 中空笼状羟基铁，石墨烯，砷，硒，吸附 FeOOH microboxes, grophene oxide, arsenic, selenium, adsorption |
| 其他题名 | Preparation of FeOOH with Special Morphology and the Adsorption Study to Arsenic or Selenium-Contaminated Water |
| 学位专业 | 环境工程 |
| 中文摘要 | 随着矿物的开发以及工业生产的加速，砷、硒等重金属污染物质在水环境中的浓度逐渐增加，由此导致的水污染报道也日渐频繁。在我国，砷、硒的矿藏储备量以及开采程度均居世界前列，砷、硒的污染现状也同样不容乐观。在众多水体净化方法中，吸附法被认为是去除水中重金属污染物质最为有效的方法。因此，面对日益严峻的水体砷、硒污染，研究开发新型吸附材料对推进重金属污染物的控制治理有着十分重要的意义。 羟基铁（FeOOH）由于其与阴阳离子强烈的化学结合能力以及较高的经济适用性，已成为当前应用最为广泛的吸附材料。随着对水质要求的不断提高，新型高效吸附材料不断涌现，但在应用中很难保证材料表面的活性位点能够得到充分利用。此外，具有高效吸附性能的纳米材料在水处理中的分离问题也同样困扰着吸附净化技术的发展。针对以上问题，本研究以 FeOOH为研究对象，通过控制材料的形貌制备出具有中空笼状结构的 FeOOH，并通过结构的控制使材料表面的活性位点得到充分的利用；同时通过制备 FeOOH与石墨烯的复合物来解决吸附材料的二次分离问题。系统研究并优化了两种材料的合成方法，并在此基础上对上述两种材料的吸附性能进行了研究。 为提升吸附材料表面活性位点的数量及利用率，本研究以普鲁士蓝(PB)为模板，通过模板法成功合成了由大量 FeOOH纳米片层堆积而成、具有多孔中空笼状结构的 FeOOH立方体材料。研究发现，该合成材料的比表面积为147m2/g，孔径大小为 4nm，等电点为 8.5；材料表面的 Fe元素价态为+3价，高于传统FeOOH的价态（+2~+8/3之间），能够有效的结合大量活性羟基；表面的Fe-O键长为 1.94 Å（小于传统 FeOOH的1.97 Å），这就使中空 FeOOH与重金属结合释放H的过程所需能量较小。上述性质为表面活性位点的充分利用以及吸附性能的提升提供了理论基础。 对中空笼状 FeOOH的吸附实验结果表明：该材料对 As (III)、As (V)和 Se (IV)均有良好的吸附能力， Langmuir模型拟合得出的最大吸附容量分别为192.19mg/g、250.01 mg/g和 169.88 mg/g。该材料对重金属离子的吸附速率较快，在低重金属含量（1mg/L）情况下，可在吸附剂投加后 1 min内使 Se的浓度降低至10 μg/L以下，As则可在5 min内达到水质标准。此外，利用NaOH对饱和吸附材料进行再生，吸附-解吸实验结果表明五次循环后吸附能力损失较小，该合成材料具有很好的再生利用能力。 为解决纳米吸附材料的二次分离问题，本研究采用氧化石墨烯（ GO）作为吸附材料合成的基底，利用其丰富活性官能团以及超薄片层结构来提供稳定、可塑性强的 3D空间结构支撑。通过探讨 Fe(II)和 Mn (II)对 GO凝胶形成的影响，进而利用一步水热法成功制备出 Fe (Mn)-GO复合材料。综合该复合材料的表征结果发现：Fe (II)、Mn (II)的加入会对 GO凝胶的形成起到促进作用，并且 Fe(II)能够以 FeOOH纳米颗粒的形式负载在石墨烯片层表面。此外，在 100℃低温条件下生成的 Fe (Mn)-GO比表面积为 13.64 m2/g，表面负载 FeOOH的大小为 25 nm，通过 Fe (II)和 Mn (II)的复合能够提升 GO凝胶的晶格缺陷。 对 Fe (Mn)-GO复合材料的吸附实验结果表明：该材料对As(III)和 As(V)均有较好的吸附效果，对 As(III)和As (V)的最佳反应 pH分别为 7和 5；Langmuir模型拟合得出该材料对二者的最大吸附容量分别为 123.88 mg/g和 46.71 mg/g。 此外，利用 NaOH对饱和吸附材料进行再生，吸附-解吸实验结果表明五次循环后吸附能力损失较小，该合成材料具有很好的再生利用能力。依此实验结果设计制备的升流式吸附柱反应器能够连续运行 20天内保证实际含砷水体的出水砷浓度低于 10 μg/L。 |
| 英文摘要 | With the acceleration of mineral development and industrial production, the concentration of arsenic, selenium and other heavy metal pollutants in the aqueous environment are increasing, and the water pollution has been more freuntly reported. In China, the mineral reserves and mining of arsenic and selenium are among the top in the world, and the pollution has been serious. Among the water purification methods, adsorption is considered to be the most effective method in removing of heavy metal pollutants. Facing with the increasing arsenic and selenium pollution, the development of new materials for propulsion the pollutant control is very significant. Hydroxy iron (FeOOH) has become the most widely used adsorbent due to the strong chemical binding capacity with pollutants and the affordability. With the continuous improvement of water quality requirements, new efficient adsorbent materials are emergeing, but the effectively utilize of the active sites is still the puzzle. In addition, the separation of nanomaterials from the body water is also plaguing the development of the improvement of adsorption technology. To solve the problem above, FeOOH has been regareded as the research object in this study. The hollow microboxes material constructed with FeOOH nanosheets was prepared for the fully utilize of the surface active sites, and Fe (Mn)-GO was synthesized to solve the problem of secondary separation. Additionally, the synthesization method of these two materials are systematically studied, the test of adsorption properties was also discussed. To enhance the number of surface active sites, PB was used as the templt in this study, and FeOOH microboxes constructed with numerous nanosheets was successfully synthesized. The BET surface area of the synthesized material was 147m2/g with a pore size of 4 nm and an isoelectric point of 8.5. The valence state of Fe(+3) in the surface is higher than that of the traditional FeOOH(+2~+8/3), which can effectively combine a large number of reactive hydroxyl groups. The bond length of the Fe-O bond (1.94 Å) is also shorter than the traditional ones (1.97 Å), providing convenience to release H in the chemical reactions. All these characterics enhance the full use of the surface active sites and the adsorption performance According to the adsorption results of the FeOOH microboxes, the synthesized material showed excellent adsorption capacity to As (III)、As (V) and Se (IV), with the maximum adsorption capacity of 192.19 mg/g、250.01 mg/g and 169.88 mg/g,respectively. Also, the synthesized material showed rapid adsorption rate, the Se concentration can reduce to 10 μg / L instantly in the dosage of the adsorbent and within 5 min for As at low initial concentration. In addition, the synthesized material showed good adsorption-desorption ability after five-cycle test with regeneration by NaOH. In order to improve the separation ability of the adsorbents, we choose graphene oxide as the substrate of the composited material. Based on the results of the Fe(II) and Mn(II) effect on the formation of GO gel, we synthesized Fe (Mn)-GO via an in-situ self-assembly reaction. The results showed that, both Fe (II) and Mn (II) can promote the formation of GO gel by lower the reaction temperature and Fe (II) can form nanoparticles in the GO layers. The BET surface area of the synthesized Fe(Mn)-GO was 13.64 m2/g, and the size of the Fe-nanoparticles was 25 nm. The adsorption results showed that the synthesized Fe (Mn)-GO showed good adsorption capacities to As (III) and As (V) with the maximum adsorption capacities of 123.88 mg/g and 46.71 mg/g at pH 7 and 5, respectively. The adsorption-desorption experiment shows that the Fe (Mn)-GO has good regeneration ability in five-cycle adsorption. Based on this, an up-flow adsorption adsorption reactor was also designed for the groundwater treatment, and the effluent concentration of arsenic could reach the standar (10 μg/L) within 20 days in continuous reaction. |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/37020]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 王思达. 特殊形貌羟基铁的制备及对水中砷和硒的吸附性能研究[D]. 北京. 中国科学院研究生院. 2016. |
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