木粉微结构调控及快速吸附水体重金属离子机理研究

Aiming at the deterioration of water ecology and the heavy metal pollution of water in China, it is urgent to develop new matrix with higher adsorption rate and capacity, which will address the drawbacks of traditional adsorption materials. Compared to other adsorption materials, wood flour has a higher adsorption rate, but the lower adsorption performance restricts its wide applications. This project aims at finding out the mechanism of fast-removal of heavy metal ions and improving the adsorption capacity by taking full advantages of the hierarchical structures of wood flour. Various physical and chemical methods can be employed to improve the specific surface and pore structure of wood flour. The active adsorption sites can be increased through introducing certain catechol-based reactive groups into wood structure. In addition, the permeation and difussion model of heavy metal ions’ absorption process in wood structure will be developed to derict the control and optimization of the heavy metal ions’ transferiation in wood flour. It will establish a structure-property relationship between the microstructure and components of wood flour and its adsorption performance. Consequently, this project will construct an unified system of the controlled microstructure in wood flour, the high-performance in heavy metal ions adsorption and also the absorption mechanism by influencing factors. Prospective results of this project will provide new ideas for the design and preparation of highly adsorptive wood flour materials, and are important for developing economical and effective heavy metal adsorbents.

针对我国水生态恶化、水体重金属污染日益突出，传统吸附材料在水体重金属污染处理中存在吸附速度慢、成本高等问题，本项目拟充分利用木粉多尺度孔隙结构及快速吸附特性，调控并构建木粉快速吸附重金属离子微结构，解析其快速吸附机理。通过物理化学处理调控木粉孔隙结构和孔径分布，增加木粉比表面积和吸附位点；研究水体重金属离子在木粉中吸附传质过程，构建重金属离子渗透扩散模型。阐明木粉表面形态、孔隙结构、孔径分布、比表面积、化学成分、表面活性官能团种类和数量与木粉渗透率、扩散系数及质交换系数等特性间构效关系，控制水体中重金属离子在木粉中渗透扩散过程，建立木粉微观结构、化学成分与宏观吸附性能间的关系，提高木粉吸附容量，并最终构建木粉结构与性能统一的“可控微结构—吸附性能—影响机制”关联系统。该项研究不仅能为高性能木粉基吸附材料的设计与制备提供新思路，也能为水环境中重金属离子污染快速治理提供新方法。

木粉较低的比表面积和较少的活性基团是造成木粉吸附剂吸附容量低下的根本原因，限制其广泛应用。基于木粉多尺度孔隙结构及快速吸附特性，本项目构建木粉快速吸附重金属离子微结构，并通过物理化学处理调控木粉孔隙结构和孔径分布，增加木粉比表面积和吸附位点。重点研究不同处理方法与工艺等对木粉孔隙结构和表面吸附位点影响规律，解析高比表面积、高吸附容量木粉孔隙结构调控与形成机制，阐明木粉表面形态、孔隙结构、孔径分布、比表面积、化学成分、表面活性官能团种类和数量与木粉渗透率、扩散系数及质交换系数等特性间构效关系，构建水体中重金属离子在木粉中渗透扩散模型， 揭示改性木粉对水体中重金属离子吸附机理。结合精准的化学测定技术和先进的仪器分析手段，本项目对改性木粉吸附剂材料的各方面性能进行了表征，结果表明，改性木粉吸附剂具有更大的比表面积和更多的活性吸附位点。改性木粉吸附剂通过氢键结合、静电吸引作用、金属-配体配位作用和螯合作用与重金属离子结合，提高对重金属离子的吸附容量，其对重金属离子的吸附过程符合准二级动力学吸附模型Langmuir等温吸附模型，吸附机制为单分子层化学吸附。本项目可为木材生物基高性能吸附材料的设计与制备提供科学依据与科学方法，对经济高效的水环境中重金属离子吸附剂的开发同样具有重要意义。