多层次孔结构的柔韧自支撑有机-无机杂化分子印迹膜分离葛根中染料木黄酮研究

Molecularly imprinted membrane (MIM) has received an extensive concern in the field of separation and purification due to the high selectivity and continuously separating mixtures. But one of the methods for preparation of MIM, in situ crosslinking polymerization, has encountered some limitations. For example: the imprint sites of MIM are always embedded, which can severely hamper access to imprint sites and leads to low mass transfer rate; the MIM is too fragile to apply to practical application. In order to avoid the above shortcomings, in this project a hierarchically structured porous flexible molecularly imprinted organic-inorganic hybrid membrane was prepared to separate genistein from pueraria. In this separation system, target molecules can more easily diffuse to reach an imprint site through the channels because of the macropores and mesopores structures, which would speed up the rate of mass transfer; the micropores can improve separation selectivity.The flexible organic-inorganic hybrid structure can reduce the swelling of the membrane and improve the separation selectivity; the flexiblity can improve practical application. The separation mechanisms for the hierarchically structured porous MIM was also discussed. In summary, the separation system possesses the advantages of molecularly imprinted material, hierarchically structured porous materials and membrane, therefore the system could improve membrane separation selectivity, flux, mass transfer and practical application for separation.

分子印迹膜(MIM)兼具分子印迹技术的高选择性和膜分离技术的可连续操作、易于放大、能耗低和能量利用率高等优点，已成为国内外的研究热点。其中原位交联聚合制备自支撑MIM面临三个挑战：一是膜的完整性差、易破碎；二是印迹位点常被包埋在膜内部，目标分子进出困难甚至无法到达；三是膜的渗透性差。这样就导致原位聚合MIM的应用受到限制。针对这些挑战，本项目拟制备多层次孔结构的柔韧自支撑有机-无机杂化MIM。MIM中的大孔和介孔有利于目标分子进出印迹位点，提高膜的传质效果和通量；微孔有利于选择性吸附，可保证MIM有较高的选择性；柔韧使MIM不易碎，有机-无机结构使印迹空穴不严重变形，故既可提高MIM完整性又保证其高选择性。探讨多层次孔MIM分离机理，并用于分离葛根中的染料木黄酮。本项目结果有助于深入了解多层次孔的柔韧自支撑有机-无机杂化MIM的性能和分离机理，因此具有重要的学术价值和较好的应用前景。

如何提高膜的稳定性、传质速度和渗透性能是当前分子印迹膜研究面临的重要挑战。本项目采用多种方法：纳米球自组装法、直接纳米球混合法和冷冻聚合等方法制备了染料木黄酮分子印迹膜。分别采用SEM、氮吸附解析、FTIR和TG等手段对膜的形貌和性质进行了表征，发现该方法可形成强度较高、具有多级孔结构的膜结构。采用静态吸附、动态过滤和膜渗透等实验方法考察了膜的分离性能，实验结果发现，与具有类似结构的葛根素、大豆苷元和大豆苷等比较，分子印迹膜能快速识别染料木黄酮，且具有较高的吸附容量和分离效率。通过该项目，我们发现了调控分子印迹膜的强度、膜的渗透性能的方法，制备了性能优异的有机-无机杂化分子印迹膜，可用于葛根中染料木黄酮的分离；同时本项目研究结果也为调控分子印迹膜的结构和性能奠定了坚实的理论基础。