具有多级结构的金属氧化物/碳包覆纳米纤维复合膜的制备及其对离子型有机污染物吸附性能的研究

Organic pollutants have become one of the most serious environmental problems, and the removal of organic pollutants(e.g., dyes, pesticides, and pharmaceuticals/drugs) and common industrial organic wastes (e.g., phenols and aromatic amines) from aqueous solutions is of special concern because they are recalcitrant and persistent in the environment. Ionic organic pollutants have large solubility in water. The strong mobility of ionic organic pollutants may bring greater risk to the ecological environment and human health. Recently, a great deal of attention has been focused on the application of nanostructured carbon materials as adsorbents to remove toxic and harmful organic substances from wastewater. However, the carbon materials are all in the form of powder using either template-free or inorganic templates. For the casting carbonaceous nanofiber membranes, the membranes showed free-standing property, but the mechanical strength of the membranes was not high, restricting practical application. When the materials are used as adsorbents in water medium, the powder form is not conducive to recycling and low mechanical strength of the membranes cannot resist the impact of the water flow. Therefore, searching for a flexible and high strength polymer membrane template for loading the hydrothermal carbon is necessary. Electrospinning is a versatile, simple, and effective technique to prepare one-dimensional continuous polymer fibers with diameters in the range of nanometers to a few micrometers. The electrospun fibers possess high porosity, large surface to volume ratio, easy preparation, diverse in composition, and facile modification properties, which have found wide applications. The functional fiber membranes show flexibility and satisfying mechanical strength, which can be easily recycled. Therefore, the disadvantages of the difficulty to recycle and easy aggregation for hydrothermal carbon would be resolved when we combine hydrothermal carbonization with electrospinning technique. In this proposal, we plan to prepare the hierarchical metal oxide/carbon-coatedelectrospun nanofiber composite membrane and investigate selective adsorption mechanism for ionic organic pollutants. We will investigate the phase-structure and morphology effects of metal oxide nano materials in hierarchical composite nanofibers on ionic organic pollutants adsorption, and moreover, investigate the surface functional groups effects of carbon-coated polymer matrix in hierarchical composite nanofibers on ionic organic pollutants adsorption. We will investigate the synergetic effect of metal oxide and carbon-coated electrospun nanofiber. We plan to use the large specific surface area and high surface energy of metal oxide nano materials to improve adsorption capacity and rate, use the good flexibility and easy film-forming of carbon-coated polymer matrix to improve the separation and regeneration performance. These hierarchical metal oxide/carbon-coated electrospun nanofiber composite membrane can be potentially applied in the environmental ionic organic pollutants removal.

随着现代工农业生产的发展，农药、杀虫剂、抗生素和染料等有机污染物不断进入环境中，其中离子型有机污染物，由于在水中溶解度较大，迁移性强，给生态系统与人类健康带来了严重的危害。传统的纳米结构碳吸附剂，具有较大的吸附含量，但价格贵、易团聚、使用寿命短并且容易造成二次污染。在本项目中，我们提出将静电纺丝技术与水热碳化方法结合，制备具有多级结构的金属氧化物/碳包覆纳米纤维复合膜。通过多级结构中金属氧化物纳米材料的大比表面积和高表面结合能，提高复合材料的吸附能力；通过碳包覆高分子纳米纤维较好的机械性能，提高复合膜的水流抗冲击能力；通过复合纳米纤维表面功能化，调控复合纤维膜的带电性质，研究复合膜对水中离子型有机污染物的选择吸附机理。探索金属氧化物/碳包覆纳米纤维复合膜中各组分之间的协同作用，制备出一类吸附效率高、选择性可控、再生性能好的新型吸附剂。

随着现代工农业生产的发展，农药、杀虫剂、抗生素和染料等有机污染物不断进入环境中，给生态系统与人类健康带来了严重的危害。本项目制备了一系列对离子型染料、离子型除草剂、抗生素和重金属离子等污染物有较好吸附能力的复合纳米纤维材料。通过一步水热合成方法制备了AC/MnO2/PAN复合纳米纤维，纤维表面存在大量的负电荷吸附位点，因此对阳离子染料具有非常好的选择吸附性能，可以对阳离子和阴离子染料进行快速高效分离，分离效率达到99%以上。进一步制备了中空结构Carbon@MnO2复合纳米纤维，中空结构的复合纳米纤维具有更大的比表面积和更多的吸附位点，实现了对水中Pb2+的高效去除。我们制备了负载MgSi的PAN复合纤维膜，纤维表面大量的MgSi超薄纳米片形成的多级结构，增大了纤维的比表面积和吸附位点，复合纤维膜对水中农药敌草快展现了优异的吸附移除性能，并且具有很好的再生性能。我们通过静电纺丝方法、煅烧技术与和水热反应结合，以柔性SiO2纤维为模板，制备了具有柔性的MgSi纤维膜，此纤维膜可以高效率去除有机阳离子染料。由于具有优异的机械性能，此纤维膜可以作为动态过滤膜使用，每千克MgSi纤维膜处理废水的质量是商业尼龙-6微滤膜的60倍，去除效率可达99%。我们通过粘附层修饰原位生长的方法解决了电纺纳米纤维中纳米晶体组分容易聚集和脱落的难题，利用聚多巴胺作为还原剂和粘附剂调控MnO2原位生长在纤维表面，MnO2/PDA/PAN复合纤维膜对Pb2+展现了较好的吸附性能，对实际废水样品中Pb2+的去除率在95%以上。利用同样的方法，还制备了ZIF-8功能化纳米纤维膜，此纤维对水中的抗生素污染物四环素具有非常好的吸附移除能力。此外，我们还制备了兼具吸附性能和高效滤过性能的多功能复合纳米纤维膜，支化聚乙烯亚胺接枝的聚丙烯腈纤维膜和Cu-BTC修饰的双层复合纳米纤维膜，这两种纤维膜分别对胆红素以及肌酐和尿素展现了优异的去除能力。本项目所制备的多种复合纳米纤维膜吸附剂展现了优异的吸附性能和良好的可再生性能，有广阔的应用前景。