由焦化废水污泥制备碳基电极材料的过程控制机制及其电化学作用原理

Pyrolytic conversion of sludge to carbon is a promising resource-recovery technology for the management of wastewater sludge. Coking wastewater sludge is a typical industrial wastewater sludge, which is commonly disposed by landfill and incineration. These methods, however, are difficult to achieve the purpose of resource recovery. Taking into account that the coking wastewater sludge contains relatively high amounts of carbon, a variety of elements including N, P and Fe, and abundant surface functional groups, here we propose the concept of using coking wastewater sludge to prepare carbon-based electrode materials for applications in various electrochemical cells. In this proposal, we will (i) analyze the composition of the coking wastewater sludge or the functional bacteria, (ii) establish strategy for the preparation of sludge-derived carbon materials with controllable structure and performance, (iii) investigate the characteristics including element composition, element concentration, extracellular polymeric substance structure, extracellular polymeric concentration on the performance of the resulting carbon materials such as surface morphology, pore structure, specific surface area, conductivity, surface functional groups, and level of doping with N, P, and/or Fe, (iii) examine its electrochemical performance when being used in fuel cells, supercapacitors and microbial fuel cells, and (iv) eventually disclose the inherent relationships among the sludge characteristics, methods and parameters of pyrolysis, surface properties of sludge-derived carbon and electrochemical performance of sludge-derived carbon. This work will present a new approach for the effective management of coking wastewater sludge, and provide theoretical insights into the development of industrial wastewater sludge-derived carbon for electrochemistry application.

污泥高温碳化制备功能性碳材料是污泥资源化处置的一项具有发展前景的技术。焦化废水污泥是一种典型性工业废水污泥，常规的处置方法如土地填埋及焚烧难以做到资源化利用。考虑到其具备较高碳值，含有N、P、Fe等元素，具有丰富的表面官能团，本项目提出利用焦化废水污泥高温碳化制备碳基电极材料。通过对焦化废水污泥/功能微生物的组分进行分析，寻找污泥碳材料结构可控、性能可控的制备方案，考察污泥元素组成、元素含量、胞外聚合物组成、胞外聚合物含量等对污泥碳的形貌、表面孔结构、比表面积、导电性、表面官能团、杂原子（如N、P、Fe等）掺杂等特性的影响，研究污泥碳作为电极材料应用于燃料电池、超级电容器、微生物燃料电池的电化学性能，最终阐明污泥特性-碳化条件-污泥碳表面性质-污泥碳电化学性能之间的内在关联。项目的顺利开展将为焦化废水污泥资源化处置提供新的途径，为工业废水污泥用作电极材料提供理论和技术支撑。

污泥高温碳化制备功能性碳材料是污泥资源化处置的一项具有发展前景的技术。焦化废水处理污泥是一种典型性工业废水污泥，常规的处置方法如土地填埋及焚烧难以做到资源化利用。考虑到其具备较高碳值，含有N、P、S、Fe等元素，具有丰富的表面官能团，本项目旨在利用焦化废水污泥高温碳化制备自模板、自活化、及自掺杂的类石墨烯多孔碳，并用作为碳基电极材料。揭示了影响杂原子自掺杂污泥碳结构和电化学性能的关键因素；阐明了生物介导下微生物与无机物之间的相互作用与碳材料结构及电化学性能的内在联系；厘清了碳前驱体形貌特征对材料结构和电催化活性的影响规律；实现了高电化学活性污泥碳的可控制备；并考察了其在电催化氧还原、水解析氢、水解析氧等领域的潜在应用前景。影响材料结构和性能的关键因素包括污泥中Fe、N、P含量以及微生物与矿物之间的强相互作用。经过硝化驯化后焦化废水污泥前驱体制备的碳材料具备层次分明的类石墨烯结构、合适的孔径分布、较高的杂原子（N、S）掺杂程度、良好的导电性；由于赝电容存在，在电流密度为1 A g-1条件下1 M硫酸中比电容值高于石墨烯理论值；在氧还原方面，其氧还原性能也接近于Pt/C电极。将无机污泥中铁聚合物通过微生物异化铁还原成矿后形成铁矿与活菌包覆物，并以此为前驱体，合成了包覆Fe2P活性纳米颗粒（3 nm）的类石墨烯多孔碳材料；在碱性电解液中氧还原的起始电位和半波电位分别为1.01 V和0.85 V，与商用Pt/C相近，以此材料制备的空气阴极应用到微生物燃料电池时，其最大功率密度为1859.3 mW m-2，比负载Pt/C阴极高出759.4 mW m-2。项目研究结果为焦化废水处理污泥资源化处置提供新的途径，为污泥碳的可控制备及其在电催化方面的应用提供理论和技术支撑。