表面改性纤维素纳米纤气凝胶的制备与结构调控及其对重金属离子的吸附行为与机理的研究

As a novel nanomaterial, cellulose nanofibrils (CNFs) own plenty of extraordinary properties, such as excellent mechanical properties, optical properties, rheological properties, etc. Moreover, CNFs are originated from many resources, and also it is quite simple for their production. Therefore, they have become the current frontiers and hot topics in many research fields. In this proposal, several kinds of plant fibers will be used as the raw materials to assess their nanofibrillation process under various conditions using high shear homogenization. The influence of high shear homogenization on the morphologies，structures and properties of the obtained CNFs will be investigated. Different chemical reactions will be applied to the as-prepared CNFs to render their surface various kinds of functional groups, which have a strong affinity upon heavy metal ions. Cellulose aerogel based bioadsorbents with large specific surface area and high porosity will be prepared via freeze-drying or supercritical drying of the modified CNFs hydrogels. The influence law of the preparation conditions, such as freezing temperature, freezing mode, CNFs concentration, on the pore structure of aerogels will be revealed. To enhance their water stability, aerogels will be chemically crosslinked. The adsorption efficiencies of cellulose aerogels towards different heavy metal ions, the adsorption thermodynamics, the adsorption kinetics and the isotherm modals will be studied. The optimal adsorption conditions will be found out. The reusability of the aerogel bioadsorbents will be studied as well. This study is expected to advance the inter-disciplinary science at the interface of biopolymers and the environment. It will be of great importance for the development of cellulose nanotechnology as well as a value-added application of cellulose resources.

纤维素纳米纤作为一种新型纳米材料，具有优异的力学、光学、流变学等性能，而且来源丰富、制备工艺简单，因此成为当前很多领域的研究前沿和热点。本项目拟选用多种植物纤维为原料，通过高剪切均质法分离纤维素纳米纤；研究机械力对纳米纤形貌、结构和性能的影响；采取多种化学改性方法在纤维素纳米纤表面引入大量对重金属离子具有强吸附能力的官能团；通过冷冻干燥和超临界干燥技术制备高比表面积，高孔隙率的改性纤维素纳米纤气凝胶，阐明冷冻温度、冷冻作用方式、纳米纤含量等因素对气凝胶多孔结构的影响规律；通过化学交联反应提高气凝胶的水稳定性；考察其对水中不同重金属离子的吸附性能，研究吸附热力学、动力学和吸附等温线模型，探索最佳吸附条件，揭示吸附机理；研究吸附材料的可再生利用性。该项目研究将推动天然高分子科学与环境科学的学科交叉，对于丰富和发展纤维素纳米技术、实现纤维素资源的高值化利用具有重要意义。

纤维素纳米纤作为一种新型纳米材料，具有优异的力学、光学、流变学等性能，而且来源丰富、制备工艺简单，因此成为当前很多领域的研究前沿和热点。本项目选用多种植物纤维为原料，通过对预处理和均质处理工艺的调控和优化达到纤维素纳米纤高效分离的目的，对于减低能耗、实现纤维素纳米纤的大规模生产具有重要指导意义。通过表面化学改性的方法使纤维素纳米纤上覆盖大量对重金属离子具有强吸附作用的官能团。将改性纤维素纳米纤制备具有高孔隙率、高比表面积、耐水性优良的气凝胶用于重金属离子污染水体的高效净化处理。特别是本项目研发的超支化多胺改性纳米纤维素气凝胶的六价铬吸附量达370mg/g，是迄今报道的铬吸附量最高的吸附材料。论文审稿专家评价：该材料实现了材料制备方法和吸附性能的重大突破。通过原位生长法使纤维素纳米纤表面覆盖二氧化锰纳米颗粒，能有效实现有机染料污染水体的净化。本项目首次提出的基于纳米纤维素气凝胶制备高效水处理材料的学术思想得到国内外多个课题组的借鉴和发展，论文被国内外同行多次引用。该项目研究将推动天然高分子科学与环境科学的学科交叉，对于丰富和发展纤维素纳米技术、实现纤维素资源的高值化利用具有重要意义。