石墨烯基气凝胶表面含氧结构调控及强化抗生素去除机理

The potential applications of graphene-based aerogels in pollutant treatments have attracted wide interest and become one of the hottest research areas in environment science. However, attempts to take deep insights about the oxygen-containing structure of graphene oxide (GO) nanosheets on construction and designing of graphene-based aerogels with enhanced removal of antibiotics are lacking. The research in the field of GO mainly oversimplifies the surface microchemical environment of GO, and the realistic state of oxygen-containing structure including oxygen-containing functional groups and oxidation debris on GO nanosheets is ignored. In this study, GO nanosheets is selected as research object, the structure-activity relationship between oxygen-containing structure and the construction, surface modifications of graphene-based aerogels and its adsorption performance of antibiotics will be discussed. The objectives of this study are (1) to modify the distributions of oxygen-containing functional groups, sizes of sp2-sp3 phases, et al. by altering the reaction temperatures and pH, and discuss the chemical and physical states of oxygen-containing structure and its regulation methods; (2) to clarify the effects of the oxygen-containing structure on the self-assembly, surface modification and mechanical stability of graphene-based aerogels; (3) to evaluate the adsorption/recycle process and molecule interactions mechanisms of antibiotics on regulated graphene-based aerogels, and provide a theoretical basis and an engineering reference for improving the performance of graphene-based materials in environmental pollutant treatments.

石墨烯气凝胶及其污染控制应用已成为国际环境领域研究热点之一，但有关表面含氧结构对石墨烯气凝胶构筑、修饰及其强化吸附机理缺乏深入研究；对石墨烯纳米片层通常采用简化结构模型，忽略了纳米片层表面含氧结构包括表面含氧官能团与氧化纳米碎片的真实存在状态。为此，本项目选择氧化石墨烯纳米片层为研究对象，考察其表面含氧结构对石墨烯基气凝胶构建、修饰的调控作用，揭示石墨烯气凝胶对典型抗生素增强去除性能、作用机理与构-效关系。通过控制环境温度、溶液pH等因素，改变纳米片层上含氧官能团种类和数量、sp2-sp3结构相对比例等，探讨氧化石墨烯表面含氧结构及其调控方法；以此构建石墨烯基气凝胶，阐明含氧结构与片层自组装、表面修饰有效性和结构稳定性的内在机理；评价片层调控的石墨烯基气凝胶对水体抗生素的去除和循环再生性能，探讨其界面作用机理与构-效关系，为构筑高性能石墨烯功能材料及其污染控制应用提供理论依据和技术支撑。

二维层状氧化石墨烯（GO）作为石墨烯的一种代表性衍生结构，因其可大批量廉价制备、良好水分散性、易表面修饰改性和可加工等特点，是目前石墨烯基材料环境应用最重要的研究对象。以二维GO纳米片层自组装形成的三维石墨烯气凝胶宏观结构，不但良好保持了原本石墨烯自身的优异特性，还兼具超低密度、易回收等新优势，在水体污染物控制等领域展现出更为诱人的应用前景。作为石墨烯气凝胶的基本构建单元，二维GO纳米片层存在形态决定了构建的石墨烯气凝胶的结构特性和应用潜力。然而，由于GO片层结构的复杂性，目前对氧化石墨烯的真实结构仍没有定论，对于GO片层化学组成及空间形貌的有效调控的研究鲜有报道。准确认识和有效调控GO片层存在状态，对于提高纳米片层自组装形成的气凝胶的结构稳定性、片层修饰有效性及对水体污染物的吸附容量都具有重要意义。本项目以GO纳米片层上最重要组分——含氧结构为研究点，旨在探索GO片层的有效调控手段，以深入认识GO真实结构、充分发挥GO片层潜力，并组装石墨烯气凝胶探讨片层结构优化对三维气凝胶组装过程和性能提升的构-效关系。本研究系统探讨了环境温度和溶液pH等参数对GO表面含氧结构和片层空间形貌的内在关联，从分子水平和微观尺度上阐明在外界环境条件的诱导下，GO片层化学组成和空间存在形态的转变过程；开发了一种石墨烯纳米片层有序褶皱的简单方法，实现并证实了GO片层表面含氧官能团转化过程，加深了对GO纳米片层真实结构的认识；系统研究了GO结构与构建的石墨烯气凝胶的自组装行为、片层间连接方式及交联剂聚乙烯醇共价成键的相互关系，并进一步考察了三维气凝胶对水体污染物的去除性能，强调了GO片层结构的有效调控对石墨烯气凝胶性能提升、环境应用潜力拓展的重要意义。本研究关注了最基础的GO结构，最终成功构建了高性能石墨烯基气凝胶，实现了以化学结构认识指导材料性能提升，试图为认识GO纳米片层分子结构和调控提供理论参考，为三维石墨烯气凝胶的环境应用提供技术支撑。