基于碳层纳米通道构建膜界面臭氧催化氧化体系的研究

For the advanced purification of micro-polluted water in Tai Lake, the development of an in-situ catalytic ozonation system of GO/O3 was proposed in this work, by assembling functional graphene oxide (GO) sheets on polytetrafluoroethylene (PTFE or Teflon) membrane interface and creating a carbon channel nanostructure for both filtration and reaction process. It was believed to overcome the inherent disadvantages of convention catalytic reaction by carbon materials, including medium removal efficiency, no reaction pathway control and solid-liquid separation with difficulty. Firstly, the responding relationship between carbon layer structural characteristics on membrane interface and pollutants separation and catalytic ozonation performances would be investigated, in order to optimize the design and preparation of composite membrane. Based on kinetics of target organics degradation, the relative contribution of both solid-phase surface oxidation and bulk hydroxyl radical (HO•) reaction are analyzed, respectively. Afterward, the determining factors for dominated reaction mechanism in system are identified, and actual controlling of micro-environment on membrane interface would be expected. Thirdly, the influences of organics background on the removal behavior of typical micro-pollutants by in-situ GO/O3 process are also studied, while the primary cause of membrane property aging would be elaborated in detail, to provide the concept design of reactor. In brief, it is believed to promote the application of carbon nano-material in the field of water treatment, by coupling catalytic oxidation and membrane filtration, which would play a positive role in enriching the exiting theory of heterogeneous reaction.

本课题从太湖微污染水体深度净化的现实需求出发，针对传统碳质材料催化臭氧氧化法“效能不突出、机理不可控和固液难分离”等缺点，提出将功能化石墨烯（GO）薄片有序铆固于聚四氟乙烯（PTFE）膜表面，以层间间距作为分离与反应通道，构建原位臭氧催化氧化（GO/O3）体系。本课题拟基于碳层结构特性与污染物分离、臭氧催化性能的响应关系，开展复合膜的设计与功能优化。运用动力学参数解析法，表征表面催化氧化与均相HO•反应在污染物降解过程中的相对贡献率。通过探究影响体系中主导反应机理的关键因素，建立调控碳层微环境的可行方法。以膜界面GO/O3体系为反应平台，考察实际太湖水体中不同背景有机物对微污染物去除行为的影响，揭示导致复合膜性能老化的可能原因，提出与方法相适应的反应器原型设计。总之，本课题通过耦合催化氧化与膜分离过程，将有助于丰富现有非均相反应理论，为碳纳米材料在水处理领域中的应用开辟新思路。

为有效应对水体中微污染物的潜在风险，本项目通过将碳纳米管（CNTs）、还原氧化石墨烯（rGO）和氮掺杂石墨烯（NG）等多型碳纳米材料负载于尼龙微滤膜表面，构建了新型膜界面微尺度反应平台。通过系统考察碳材料外形尺寸、负载配比和表面基团组成等因素对功能碳层结构特性的影响，形成了提升复合膜催化性能与过水能力的具体思路。研究结果表明，rGO/CNTs复合膜具有优良的低压过水性能，能够在极短的接触时间（<1s）内活化过硫酸盐（PS），经表面络合氧化和自由基反应，有效降解水中微量的磺胺类抗生素（SMX）。得益于碳层吸附过滤与催化氧化过程的耦合，上述体系充分发挥了碳纳米材料高反应活性的特点，同时克服了传统分散催化剂回收困难、易于流失等固有缺点。在此基础上，将NG作为碳层改良剂，建立了NG/rGO/CNTs原位催化氧化体系。得益于碳层表面密集的Lewis碱活性基团，该体系在不同溶液pH、离子强度和背景有机物等条件下，表现出比rGO/CNTs复合膜更高的目标物去除效能、更好的低压过水性能和更低的产物毒性水平。作为理论研究的延伸，本项目还提出了一种以原位催化氧化法为核心的水深度处理新方法，其采用连续恒压过滤的模式实现了对水中微污染物的高效净化，并具备复合碳层原位再生功能。上述成果为碳纳米材料在水体污染控制领域中的应用推广提供重要支撑。