MFC阴极辅助MBR膜在线自清洗机制研究

Cathod in Microbial fuel cells (MFCs) have been conceived as a versatile assistance technology to achieve sustainable wastewater treatment. Hence, it is time to intensively studied and examined how to coupling cathod with MBR. In this plan, PVDF microfiltration membrane modified by active carbon mixed with rGO and PTFE are proposed to play double roles: catalyst layer with electron conduction and membrane seperation. Oxygen therefore undergoes reduction to produce a substantial concentration of caustic soda and hydrogen peroxide on the surface of cathodic membrane controled by external circuit or resistance, which can be utilized to clean membrane itself for membrane fouling control. Meanwhile, the mechanism of this cleaning process will be also deeply investigated, including some correlation between cleaning active ingredient and oxygen reduction reaction pathway, bonding of active carbon mixed with rGO and PTFE, or probability of electro-catalytic three-phase interface. Furthermore, a dynamic production and consumption of the caustic soda and hydrogen peroxide will be also studied in long-term membrane fouling These prospective studies would provides some important information regarding multifunctional MFC's cathod, MBR cleaning in place, fouling control and furthermore potentially practical MFC application on the future development of this promising yet early-stage technology.

MFC阴极在废水处理中可发挥多样的可持续辅助功能。本项目拟深入研究MFC耦合MBR，首先用两种碳材料活性炭和还原氧化石墨烯（rGO）混合物制备C-PTFE改性PVDF微滤膜，使其兼具MFC阴极催化、MBR过滤两个功能，通过MFC阴极优化和外电路控制阴极膜氧还原反应，达到辅助MBR膜自产清洗剂氢氧化钠和双氧水的目的，实现MBR膜在线自清洗。研究将阐明氢氧化钠和双氧水的合理浓度调控机制，揭示活性炭、rGO与PTFE粘结形式和催化层氧还原反应三相界面存在规律，以及氢氧化钠和双氧水动态生成、消耗对膜污染物的去除和预防膜污染的长效机理。项目有望拓展MFC阴极功能，凸显MFC实际应用前景，为MBR膜在线清洗和膜污染的预防方法提供一种新思路。

本项目拟研究MFC耦合MBR，首先用两种碳材料活性炭和还原氧化石墨烯（rGO）混合物制备C-PTFE改性PVDF微滤膜，使其兼具MFC阴极催化、MBR过滤两个功能，通过MFC阴极优化和外电路控制阴极膜氧还原反应，达到辅助MBR膜自产清洗剂氢氧化钠和双氧水的目的，实现MBR膜在线自清洗。项目执行至今，围绕PVDF导电过滤膜已取得的成果主要包括三个方面：（1）开发实验室用膜反应器并已或国家发明专利授权，该反应器可用于PVDF膜测试，组装方便，测试实验可精确控制，具有显著的标准化和市场价值；（2）利用原子自由基聚合（ATRP）、非溶剂致相转化（NIPS）和浸渍法制备了无机-有机复合平板膜Na2S2O8@PVDF-g-PDMAEMA/PVDF。将该膜用于MCR实现原位高级氧化和过滤增效去除水中水中抗生素氧氟沙星OFLX。结果表明OFLX去除率可达到54%，高于高级氧化AOPs或超滤单独使用时的去除率。研究还阐明了如何成功制备兼具正电荷和亲水特性PVDF膜的必要因素；（3）利用PVDF作为空气阴极双面粘结剂，随PVDF浓度增加，扩散层主要以β相结晶。SEM分析结果表明粘结剂使用浓度过低时造成催化层开裂，而过高浓度也会阻断导电通路。依靠Tafel和EIS测试，我们确定了PVDF粘结剂最佳使用浓度为10%，在此条件下可获得180mV的阴极开路电压和2500欧姆的总阻抗。这些重要结论有力地验证了立项设想，也为项目延伸课题提供了科学支撑。