纳米磁分离过程中粒子磁团聚和水动力行为及其对分离性能的影响机制研究

Due to the superparamagnetism, high specific surface area and easy modification characteristics of magnetic nanoparticles, magnetic nanoparticle separation technology has great application potential in sewage treatment. However, it is with great challenge to realize a wide range of magnetic nanoparticle separation efficiently. It has been shown that, during the magnetic separation of nanoparticles, the acceleration mode caused by the magnetic aggregation behavior and the hydrodynamic behavior provides a possible solution to this challenge. However, the influencing factors and action mechanism of dynamic characteristics as well as separation performances have not been clearly uncovered due to the single action mode of magnetic force and the lack of valid numerical analysis method, which seriously hinders the further development and application of magnetic nanoparticle separation. .Therefore, this project is studying on the control of force field acting on nanoparticles during magnetic separation process and the direct numerical simulation method of particle dynamic behavior, and then systematically exploring the influence of microscopic evolution characteristics of particle migration on the macroscopic separation performance under different magentic fields with the aid of experiments. This project aims to clarify the interaction relations between the distribution characteristics as well as action mode of gradient magnetic field and the dynamic behaviors of nanoparticles, and reveal the influence nature and enhancement mechanism of agglomeration and hydrodynamic behavior of magnetic nanoparticles on the magnetic separation performances, which can break through the bottlenecks of existing technologies and provide theoretical basis and experimental data support for the construction of efficient magnetic nanoparticle separation system.

磁性纳米粒子具有超顺磁性、高比表面积和易修饰等特征，以其为载体的纳米磁分离技术在污水处理领域展现出巨大的应用潜力，然而如何实现纳米粒子大范围的高效分离仍面临极大挑战。研究表明，纳米磁分离过程中粒子的磁团聚和水动力行为引起的粒子加速现象为解决这一难题提供了可能途径。但已有研究受限于单一磁场力作用模式且缺乏有效的数值分析方法，造成分离过程中粒子动力学特性及分离性能的影响机制尚未阐明，严重阻碍了纳米磁分离技术的进一步发展和应用。为此，本项目拟开展纳米磁分离过程中粒子的力场调控和动力学行为的直接数值模拟方法研究，并结合实验手段系统探究不同磁场作用下粒子微观迁移演变特性对宏观分离性能的影响规律，明确梯度磁场分布特性及作用模式与纳米粒子动力学特性间的作用关系，揭示磁性纳米粒子的磁团聚和水动力行为对其分离性能的影响本质和增强机制，为突破现有技术瓶颈和构建高效纳米磁分离体系提供理论依据和数据支撑。

低梯度磁分离模式为大幅提升磁性纳米粒子分离性能提供了有效途径，但相关粒子动力学特性及分离性能提升的影响机制尚未阐明，阻碍了纳米磁分离技术的发展与应用。为解决这一难题，本项目从磁分离粒子动力学数值模拟方法、磁场源设计与磁场力调控方法、磁性纳米粒子制备方法、粒子水动力行为和磁团聚行为及其对分离性能的影响等方面开展了较为系统的研究工作，为构建高效磁分离模式及推进纳米磁分离技术突破奠定基础。代表性成果包括：（1）构建了涵盖观测剂和磁性纳米粒子溶液在内的磁场-流场-双浓度场耦合模型，以及基于蒙特卡洛法和解析法的粒子三维磁团聚行为分析模型，为探究磁分离过程中粒子水动力行为和磁团聚行为提供了有效分析手段。（2）提出可变静电斥力与磁吸引力竞争的粒子电磁力场调控方法，实现粒子磁团聚行为的定向主动调控，并发明稳定性强且可调的磁性纳米粒子溶液制备方法，为探究可控磁团聚行为对磁分离性能的影响提供了有效途径。（3）阐明了磁性纳米粒子水动力行为和磁团聚行为对纳米磁分离过程的影响规律及性能提升的作用机制，发现了磁团聚行为在提升分离性能方面的主导性，为提升磁性纳米粒子分离性能提供理论依据和参考。（4）验证了所制备的磁性纳米粒子溶液在阴离子丽春红染料污水和核污水处理中应用的可行性，解决了传统磁性纳米材料在污水处理中面临稳定性与可回收性取舍困境，为低磁场下实现大范围高效纳米磁分离提供了可能。