阴离子型膨润土磁性纳米复合材料的制备及其吸附废水中重金属离子的研究

Heavy metal wastewater treatment was hot issue in the chemical industry and environmental protection. Bentonite magnetic nanocomposites have a good potential for heavy metal ions removal from wastewater. However, Fe3O4 nanoparticles that integrated with bentonite are mostly without chemical modification in the present, which leads to corrosion and oxidation of Fe3O4 easily. Meanwhile, unmodified Fe3O4 nanoparticles have less improvement of adsorption performance for bentonite magnetic nanocomposite materials. In addition, no study has investigated the effect of nano-Fe3O4 content on bentonite magnetic nanocomposites performance during the preparation process yet. The project is to prepare anionic bentonite magnetic nanocomposites and investigate their adsorption of heavy metal ions in wastewater. Anionic layered bentonite would be firstly integrated with modified nano-Fe3O4 through different preparation methods and optimum technological conditions. The effect of the nano-Fe3O4 content on adsorption performance and magnetic separation ability of the composites would be investigated, the heavy metals adsorption mechanism of anionic bentonite magnetic nanocomposite materials would be discussed, the changes of adsorbents performance brought by the integration of nano-Fe3O4 with anionic bentonite would be analyzed, the competitive adsorption of a variety of heavy metal ions on anionic bentonite magnetic nanocomposites would be checked, and finally to deal with the real heavy metals wastewater. The results of the research project will be useful not only for the development of anionic bentonite magnetic nanocomposite materials, but also for the engineering application on heavy metals wastewater treatment.

重金属废水处理是化工环保中的热点问题。膨润土磁性纳米复合材料对废水中的重金属离子有很好的去除潜力，但目前与膨润土结合的纳米Fe3O4大多是未经化学修饰的，容易发生腐蚀和氧化，同时对膨润土磁性纳米复合材料的吸附性能提升作用有限，制备过程中尚未研究纳米Fe3O4含量对磁性复合材料的影响。本项目拟开展阴离子型膨润土磁性纳米复合材料的制备及其吸附处理重金属废水的研究，首次将阴离子型层状膨润土与改性纳米Fe3O4进行复合，获得最佳的制备方法和工艺条件，并考察制备过程中磁性纳米Fe3O4加入量对复合材料吸附性能及磁分离性能的影响；研究阴离子型膨润土磁性纳米复合材料对重金属离子吸附机制，明确改性纳米Fe3O4与阴离子型膨润土结合带给吸附剂的性能变化；开展多种重金属离子竞争吸附研究；对含重金属离子的实际废水进行处理。本项目的实施将为阴离子型膨润土磁性纳米复合材料的开发及其工程化处理重金属废水奠定良好基础。

膨润土磁性纳米复合材料对废水中的重金属离子有一定的去除潜力，但其吸附性能仍有明显的提升空间，且未经化学修饰的磁性纳米Fe3O4容易发生腐蚀和氧化，不利于实际的环保应用。本项目在国家自然科学基金项目的资助下，开展了阴离子型膨润土磁性纳米复合材料的制备及其吸附重金属规律的研究, 成功掌握了阴离子型膨润土与磁性Fe3O4的复合方法，先制备Fe3O4磁流体，然后在磁流体超声分散的过程中加入膨润土进行水热合成，即可制备得到磁响应能力强、磁土结合牢固的磁性膨润土，确定了复合材料中的最佳加磁量应控制在复合材料总质量的20%左右；同时，项目组采用了单一有机修饰和两种有机物联合修饰磁性膨润土的方法，获得了磁性柠檬酸膨润土、磁性乙酸膨润土、壳聚糖/羧甲基纤维素钠联合修饰的磁性膨润土、壳聚糖/聚乙烯亚胺联合修饰的磁性膨润土等一系列磁性有机膨润土，明显地提升磁性膨润土的吸附重金属离子的性能，并有效避免了磁性Fe3O4的氧化和腐蚀，制备的阴离子型膨润土磁性纳米复合材料对Pb(II)、Cd(II)、Cu(II)、Mn(II)及Cr(VI)重金属离子吸附性能优良、磁分离性能好、性质稳定；掌握阴离子型膨润土磁性纳米复合材料吸附重金属离子的主要特性，明确了复合材料吸附重金属离子的主要机制包括表面沉淀、化学络合、静电吸附、离子交换及微孔固定；此外还进行了材料的循环利用、实际废水处理及吸附典型有机污染物的探索。本项目的实施为阴离子型膨润土磁性纳米复合材料的开发及其工程化处理重金属废水奠定良好基础。本项目实施期间已有4项获得授权，还有6项申请的国家发明专利，其中: 发表了22篇学术论文，其中SCI 收录8篇、EI收录7篇；培养了博士2人，硕士生9人，项目成果满足计划书的要求，达到结题条件。