基于废水中酚类污染物去除与资源化的导电共聚物合成及其赝电容行为研究

Phenols are considered as one of the primary pollutants in wastewater due to their toxicity to aquatic life. Aerobic biological technology has been widely used for phenol removal, but it turns to be an energy-intensive process which proceeds at a relatively slow rate. Electrochemical oxidation can allow fast removal of phenol pollutants but the production of polymeric compounds leads to the passivation of the electrode. Here we propose the concept of using electropolymerization to synthesize copolymer on the electrode surface from the aqueous solution which contains phenol (or other phenol derivatives) and a conductive polymer monomer (e.g., aniline, pyrrole or thiophene). The resulting copolymer can be directly used for supercapacitor application without the need to be peeled off from the electrode. Thus, this technology will enable fast removal of phenol pollutants and simultaneously allow resource recovery from wastewater. Controllable electrosynthesis of copolymer with pseudocapacitance can be achieved by varying the experimental conditions. Efforts will be devoted to understanding the copolymerization mechanism and relationships among the micro-/nano-structure, chemical composition, and pseudocapacitance of the resulting copolymer. In addition, the principles and operational conditions of this technology for real phenolic wastewater treatment will be investigated, with aims to achieve rapid and efficient removal of pollutants and obtain pseudocapacitance products. This work will present a new approach for pollutant removal and resource recovery from phenolic wastewater, and provide scientific insights into the development of phenol-based environmentally friendly conductive copolymer for supercapacitor application.

酚类废水生物毒性大，利用常规的好氧工艺能够实现酚类污染物的去除，但该方法较为耗能且处理速度慢。传统的电化学氧化处理速度快但容易生成惰性酚类聚合膜造成电极中毒。本项目提出采用电化学氧化聚合方法使得酚类有机物与常规导电聚合物单体（如苯胺、吡咯、噻吩等）在电极表面原位形成共聚物，且共聚物不需要从电极剥离，可直接作为超级电容器电极材料，达到酚类污染物在去除的同时并资源化的目的。通过化学组成控制、成核控制、取向生长等结构和形态控制，实现具备赝电容特性共聚物的可控合成，并阐明共聚机制及共聚物微纳结构-化学组成-赝电容行为三者之间的内在关系。进而针对真实酚类废水，寻求能够实现酚类污染物有效、快速去除，且聚合产物具备赝电容特性的电化学氧化工艺原理和工艺条件。本项目旨在为废水中酚类物质去除与资源化提供新的途径，为开发基于酚类导电共聚物环境友好的超级电容器电极材料提供科学理论根据。

含有酚类污染物的工业废水广泛存在，传统方法无论是好氧生物工艺抑或是高级氧化工艺将酚类物质矿化去除，尽管技术较为成熟，但都存在高耗能的弊端性，亟待发展能够将酚类污染去除并实现资源化利用的新工艺。为此，本项目围绕电化学氧化方法实现废水中酚类污染物去除与资源化展开，主要研究内容包括具备赝电容特性酚类共聚物的可控合成及性能表征、共聚物微纳结构-共聚作用方式-赝电容行为三者之间的内在关系、酚类污染物资源化的功能电极材料设计与应用等方面。研究发现，通过电化学氧化方法利用液相苯酚电聚合，以聚苯胺（PANI）、聚吡咯（PPy）、氮掺杂石墨烯（N-rGO）为阳极材料，可以选择性地原位合成具备高导电性和氧化还原活性的酚类共聚物，物理、化学表征证实了反应的主要产物为对苯醌（BQ）/对苯酚（HQ），其表现出优良的电容特性。经过BQ/HQ修饰的PANI电极，其比电容（553 F g-1）为未经修饰的PANI电极的1.3倍，且表现出更好的循环稳定性，2000圈充放电后电容保留值为88%，远高于未经修饰电极的51%。核磁共振氢谱、傅里叶变换衰减全反射红外光谱、X射线光电子能谱等表征揭示了BQ/HQ与基底电极之间主要是通过π-π堆积、氢键和化学掺杂等共聚作用方式进行聚合。进一步利用BQ和HQ之间良好的赝电容性能和快速的电子转移能力，构建基于导电共聚物电极材料的电化学反应器。发现了导电共聚物可介导生物电子传递，提高微生物燃料电池（MFC）产电性能；证实了木质素（lig）导电聚合物（PPy/lig）作为电Fenton反应阴极材料，能有效促进氧还原成H2O2，提高污染物降解效率。相关研究结果为具备赝电容特性酚类共聚物电化学可控合成、基于酚类共聚物功能电极材料设计与原位利用提供了理论指导和基础数据。