纳秒脉冲电场下水化离子在纳米通道中传递行为的调控机制

Controlling mechanism of confined hydrated ion behavior under the external electric field becomes a common basic problem in focused researches of many fields. Nanosecond pulsed electric field, as one of the promising techniques, has characteristics of high efficiency and low energy consume, which presents extensive potential applications in ion separation. The existing research methods are hard to fully describe the transport behavior of ions in nanochannel under the external electric field because the system is multiscale in length and timescale. Towards on the ordered nanoporous material design, the innovation in this project is to develop a novel combined research methods based on molecular dynamics and latest the macrotransport theory. Molecular dynamics will be used to investigate the microstructure of ionic hydration variation induced by the nanosecond pulsed electric field. Subsequently, the ionic flow resistance distribution in the interfacial layer will be calculated. The quantitatively relations between the confined ionic dynamic characteristics in the reduced unit and its phenomenological transport parameters in macroscopic nanoporous media will be established by using the macrotransport theory. Different kinds of ion selectivity and flux under the pulsed electric field will be evaluated and the optimized material structure parameters and external condition will be provided. This study aims to shed light on the flow resistance responsive of different ions to the confined space size and pore wall interfacial chemical properties and illuminate the synergy mechanism of complex interfacial and external electric field effect on the confined ions transport. The mathematic relation between microscopic molecular description and ionic transport properties in macroscopic material will be eventually constructed, which is essential to provide theoretical basis for design of ion separation systems with high efficiency and low energy consume. Moreover, this study will provide a novel route to realize the connection from molecular insights derived from molecular dynamics to macroscopic model and engineering experiment.

外电场作用下受限水化离子的调控机制是许多领域热点背后的共性基础问题，新兴的纳秒脉冲电场技术有望为低耗高效的离子分离带来广阔前景。由于体系涉及跨尺度的多级空间及时间结构，现有手段难以全面描述电场作用下离子在纳米通道中的传递行为。本项目创新地将分子动力学模拟与宏观输运理论相结合，以具有周期性纳米孔隙的材料为对象，从分子水平研究纳秒脉冲电场下离子水化微结构变化，计算离子在纳米受限界面层的流动阻力分布；通过宏观输运理论建立离子在微观特征单元内的受限动力学特征与其在宏观材料传递参数的定量关系；通过选择性与通量的分析，优化通道微观结构参数与外场条件。项目预期将揭示离子流动阻力对界面受限尺寸、化学性质的响应规律，阐明界面复杂结构与外场作用的匹配机制，建立微观分子描述到宏观材料中离子传递特性的联系，为开发低耗高效离子分离系统提供理论依据。同时,也为分子动力学模拟结果与宏观模型及工程实验的衔接提供全新思路。

外电场作用下受限水化离子的调控机制是许多领域热点背后的共性基础问题，低耗高效的离子分离过程的开发具有广阔的前景。项目首先利用分子动力学模拟，系统评价了电场强度、孔径尺寸、修饰基团等对(Mg2+/Li+，K+/Na+以及Ca2+/Na+体系)分离机制的影响；在此基础上系统考察了不同种类离子的水化微结构对孔道界面性质的响应，确定与能量存在依存关系的水化微结构，对各种离子水化微结构进行了系统的总结；评估了不同离子水化微结构与流体流动阻力的贡献。在分子动力学模拟研究所得到的认识基础上，针对模拟结果与宏观模型及工程实验的衔接问题，设计开发出新型基于嵌膜微流控系统，即通过将离子选择性膜嵌入微通道，构建离子浓差极化现象，通过控制流体与离子的运动，实现高效溶液脱盐、离子富集、离子分离等功能。项目达到了预期的研究目的，揭示了离子流动阻力对界面受限尺寸、化学性质的响应规律，阐明了界面复杂结构与外场作用的匹配机制，建立了微观分子描述到宏观材料中离子传递特性的联系，为开发低耗高效离子分离系统提供理论依据。同时，也为分子动力学模拟结果与宏观模型及工程实验的衔接提供全新思路。上述研究成果在国内外重要刊物上发表论文23篇，其中SCI论文20篇，封面文章4篇)；获授权专利5项。培养了多名博/硕士研究生。参与国内外学术会议10余次，包括中美化工会议keynote，香山会议专题报告等。项目负责人获省青蓝工程优秀青年骨干教师，基金委第七届化学工程青年学者学术交流研讨会“优秀论文奖”。