| 题名 | 金属有机骨架（MOFs）材料的制备及其去除 PFOS的研究 |
| 作者 | 徐毅 |
| 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 | 赵长伟 |
| 关键词 | 金属有机骨架，吸附，全氟辛烷磺酸，共存离子 MOFs，adsorption，PFOS，coexisting ions |
| 其他题名 | Synthesis of Metal-Organic Frameworks(MOFs) and its removal performance of PFOS |
| 学位专业 | 环境工程 |
| 中文摘要 | 全氟辛烷磺酸（PFOS）作为持久性有机污染物，对环境和人体健康具有潜在危害，寻找有效去除 PFOS的方法十分重要。本文选择具有规则易修饰的孔结构以及丰富主客体作用的金属有机骨架（MOFs）材料作为吸附剂，首先进行了系列 MOFs材料的制备，并将其用于吸附去除水中的 PFOS应用研究，系统研究了 MOFs材料与 PFOS吸附之间的构效关系，筛选出吸附效果较好的 MOFs材料，并进行吸附实验的深入研究，通过吸附等温线、吸附动力学、不同因素对吸附的影响以及红外等表征手段，探讨 MOFs吸附去除 PFOS的机理，并研究了在共存物质存在下，吸附剂对 PFOS的吸附效果。取得的主要研究成果如下： 1、制备了十种 MOFs材料并对其进行表征，探讨了 MOFs材料对 PFOS吸附的构效关系。研究发现，改变金属核心粒子、改变不同长度的有机配体和改性官能团都会对吸附产生影响。上述因素会导致 MOFs材料一维孔道结构以及孔道窗口的改变，从而影响 PFOS进入 MOFs一维孔道的难度。孔道越宽，孔道窗口越大，吸附剂对 PFOS的吸附效果越好。经过对比，同系列的 MIL-53(Al)-BPDC、MIL-53(Al)-NDC和 MIL-53(Al)效果较好，因此选取这三种材料作为去除 PFOS的较优的吸附剂进行后续试验。 2、以 MIL-53(Al)-BPDC、MIL-53(Al)-NDC和 MIL-53(Al)这三种材料作为吸附剂，研究了三种材料对 PFOS在不同 pH值时的吸附等温线，并对其进行了Langmuir模型、Freundlich模型和 Temkin模型拟合。结果表明，三种材料在酸性条件下吸附量更高。拟合结果表明，三种材料的吸附等温线更符合 Langmuir模型，当 pH为 4时，等温线与 Temkin模型的拟合度升高。通过 Langmuir模型得到 MIL-53(Al)-BPDC、MIL-53(Al)-NDC和 MIL-53(Al)在不同 pH值时对 PFOS的理论最大吸附量（pH=4/pH=7）分别为384.615/304.878mg/L，322.581/170.94mg/L和 66.533/66.181mg/L。吸附动力学表明，三种材料在最初80min-100min内可以完成总吸附量的 80%以上，吸附在 200min内基本达到平衡。三种材料更符合准二级动力学模型，拟合度均达到 0.999,这说明吸附速率主要有化学吸附控制。以吸附动力学曲线为基础进行内扩散模型拟合，发现拟合度较差，说明材料扩散速度受液膜扩散影响为主。 3、考察了 pH、温度和离子强度以及再生对 MOFs吸附 PFOS的影响。结果表明，MOFs材料对水中 PFOS的去除受溶液 pH的影响，酸性条件下吸附效果更高；三种材料对 PFOS的吸附量随温度升高而升高，说明吸附过程是吸热过程；在实验浓度范围内，离子强度对吸附效果没有明显影响；材料随吸附 -再生循环次数增加吸附量有所下降，其中 MIL-53(Al)下降不明显。在循环三次后，材料对PFOS的吸附量能保持到初次吸附量的 85%以上。 4、考察了腐殖酸、Ca2+、Pb2+和 AsO43-存在时，对 MOFs吸附 PFOS的影响，结果表明，腐殖酸在水中带负电，可与 PFOS发生竞争吸附，当腐殖酸浓度达到40mg/L时，会使三种吸附剂对 PFOS的吸附量减小；一定浓度的 Ca2+存在，对吸附剂吸附 PFOS起到促进作用；一定浓度的 Pb2+存在，对吸附剂吸附 PFOS起到促进作用；一定浓度的 AsO43-存在，对吸附剂吸附 PFOS起抑制作用。 |
| 英文摘要 | Perfluorooctane sulfonate (PFOS) as one class of emerging pollutants detected from water has drew great attention in recent years.How to remove PFOS from waters and ensuring the security of drinking water for human beings is very important. In this study, a series of Metal-Organic Frameworks (MOFs) were prepared and were used to adsorb PFOS from water. Structure-property relationship between MOFs and PFOS adsorption was systematically investigated. Meanwhile, MOFs with better adsorption effect were chosen for further research. Mechanism of PFOS adsorption on MOFs was studied by discussing adsorption kinetics and isotherm, influence of different environmental factors and characterization results of adsorbents. Additionally,influence of coexisting substance in water was discussed.The main conclusions are as follows: 1. Ten kinds of MOFs were synthetized and characterized and they were used to investigate structure-property relationship between MOFs and PFOS adsorption. It turned out that different central metal paticles, length of organic linker and functional groups had influence on PFOS adsorption. Factors mentioned above led to the change of structure of one dimensional channel and channel window of MOFs，which influenced the accessibility of PFOS to enter the channel. The wider the channel and the larger the window is , the better the effect of PFOS adsorption is. After comparison, MIL-53(Al)-BPDC, MIL-53(Al)-NDC and MIL-53(Al) awere chosen for further study because of their better results. 2. MIL-53(Al)-BPDC, MIL-53(Al)-NDC and MIL-53(Al) were used as adsorbents for batch experiment. The adsorption isotherms of PFOS on three kinds of materials at different pH were studied, and the Langmuir model, Freundlich model and Temkin model fitting were carried out. The result showed that the adsorption amount of PFOS was higher under the acidic condition; the adsorption isotherms of the three materials were more consistent with the Langmuir model; when the pH is 4, the fitting degree of the isotherm with the Temkin model increased. The theoretical maximum adsorption amount (pH=4/pH=7) of MIL-53(Al)-BPDC, MIL-53(Al)-NDC and MIL-53(Al) obtained by the Langmuir model was 384.615/304.878mg/L, 322.581/170.94mg/L and 66.533/66.181mg/L. According to the adsorption kinetics of three adsorbents, 80% of the total adsorption amount was adsorbed within the initial 80min-100min; Adsorption basically reached the balance within 200min. The Second-order kinetic fitted the kinetics well and the correlation coefficient was above 0.999. The result means that the adsorption rate was controlled by chemical adsorption. The intrapaticle diffusion fitting was also carried out, which showed a low fitting digree. That means the diffusion rate was mainly influenced by the liquid film diffusion. 3. The influence of pH, temperature, ionic strength and regeneration was investigated. It turned out that the effect of adsorption removal of PFOS using MOFs was affected by the solution pH, and the adsorption efficiency was higher under acidic condition; the adsorption amount of PFOS on three kinds of materials increased with the increase of temperature, which indicated that the adsorption process was endothermic; in the experimental concentration range, the ionic strength had no obvious effect on the adsorption amount; the adsorption amount decreased with the times of regeneration increased, and the amount kept above 85% of the initial adsorption amount after three cycls. 4. The effet of humic acid, Ca2+, Pb2+ and AsO43- on the adsorption of PFOS was investigated. It proved that humic acid and AsO43- had negative influence on the adsorption of PFOS; whereas, Ca2+ and Pb2+ had positive influence on the adsorption of PFOS. |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/37032]  |
| 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 | 徐毅. 金属有机骨架（MOFs）材料的制备及其去除 PFOS的研究[D]. 北京. 中国科学院研究生院. 2016. |
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