自驱动MFC-MEC梯级回收钨钼锡的化学阴极互作与Fe(III)强化效应研究

A microbial fuel cell (MFC) and a microbial electrolysis cell (MEC) are regarded as promising technologies to achieve metal wastewater treatment with simultaneous value-added metal products. The main challenges of MFC and MEC include only recovering single metals using MFC or MEC, requiring energy consumption in MEC, low power density in MFC and difficulties for utilizing power from MFC. The newly developed self-driven MFC-MEC systems can hurdle the drawbacks of MFC and MEC, and in situ utilize electricity generated from MFC to power MEC for wastewater treatment with simultaneous value-added products and no any external energy consumption. Considering the characters of practical wastewaters containing tungsten, molybdenum and tin of high concentration, and multiple components and pHs, together with merits of abiotic cathodes in self-driven MFC-MEC systems as well as Fe(III) as a mediator and abundant element on the earth, the self-driven MFC-MEC systems for sequential recovery of tungsten, molybdenum and tin from wastewater under abiotic cathode interaction and Fe(III) augumentation are proposed. Main contents include: 1) the efficiency of MFC-MEC systems for sequentially recovering tungsten, molybdenum and tin from mixed wastes, and product morphology are explored; 2) the successful interaction of abiotic cathodes in MFC-MEC systems, and the mechanism inside are clarified; 3) the enhanced system performance with the mediator of Fe(III) is explored; and 4) the relationship among abiotic cathode, Fe(III) mediator, final metal electron acceptor, and metal product in the MFC-MEC systems is elucidated based on key influencing factors and multiple batch cycle/continuous operation. This study will put forward new methods for separating and recovering tungsten, molybdenum and tin from wastewaters, clarify interaction of abiotic cathodes in MFC-MEC systems, and provide an effective strategy of Fe(III) as a mediator for enhanced system performance. Results from this work will enrich and develop the principles of MFC and MEC, as well as broaden the applicable field and scope of bioelectrochemical technologies. The theoretical importance and practical significance are thus evident.

原位利用微生物燃料电池(MFC)驱动微生物电解池(MEC)的自驱动MFC-MEC生成有价化学品是生物电化学技术重要发展方向。针对钨钼锡混合废水底物浓度高、成分复杂、pH范围广的现实，结合化学阴极MFC和MEC优势与进展、Fe(III)的介体作用与广泛存在现状，本项目提出自驱动MFC-MEC梯级回收钨钼锡的化学阴极互作与Fe(III)强化效应研究。内容包括：考察自驱动MFC-MEC梯级回收钨钼锡效能与产物形貌；剖析制约系统效能的电极互作效应与机制；提出Fe(III)强化系统性能的方法；基于关键因素的影响，阐明阴极电极、Fe(III)、金属电子受体、金属产物间关系与作用。该工作的开展将不仅提出钨钼锡的分离与回收新方法，明晰阴极电极互作效应机制，而且提出Fe(III)强化系统回收效能的新思路。这将会丰富和发展MFC、MEC基础理论，拓展生物电化学技术应用领域和使用范围，具有重要的理论和现实意义。

围绕钨钼锡废水处理与回收现状，结合生物电化学系统(BESs)特点，系统开展了自驱动堆砌式微生物燃料电池(MFCs)-微生物电解池(MECs) (Chem Eng J 2017, 327: 584-596; ZL 201610031987.2)、阴极与阳极物质流耦合环路MFCs(Sci Total Environ 2019, 651: 1698-1708)、序批式不同阴极电子受体MFCs(ChemElectroChem 2018, 5: 1658-1669; ZL 201710316396.4; ZL 201611002755.0)、双室空气阴极MFCs(Electrochim Acta 2017, 247: 880-890)、光助双室空气阴极MECs(J Photochem Photobiol A-Chem 2018, 357: 156-167)等回收/分离混合金属钨钼锡铁研究。发现钨、钼和/或锡比例、溶液pH 显著影响混合金属沉积和分离(J Hazard Mater 2018, 353: 348-359)；阐明了溶解氧、外阻、光照强度和运行时间通过影响原位H2O2生成过氧化钨和过氧化钼中产物、降低阴极氧化还原过电势而影响系统效能的作用机制；发现了钨钼组分与乙酸钠的“互惠”作用是40 L单室MECs高效回收钨钼混合金属同步利用乙酸钠副产氢气过程的关键，而阴极和阳极的电化学活性菌群随进料组分、停留时间变化的演变是系统高性能运行的基础(Water Res 2019, 162: 358-368; ZL201810685425.9)；基于原位沉积钨钼催化作用，巧妙利用厌氧/好氧条件、调控Fe(III)剂量，实现了光助阴极MFCs降解/矿化甲基橙(Appl Catal B-Environ 2019, 245: 672-680; 专利：201711156132.3)和甲硝唑(Chem Eng J 2019, 376: 119566)；并总结和展望了BESs回收金属研究现状和技术瓶颈(Book chapter, Springer, 2019)。研究结果提供了清洁有效的钨钼锡金属回收与分离新方法，丰富了BESs研究内容，拓展了其应用领域和使用范围。共发表第一标注SCI主流期刊论文9篇和论著/章1项，IF总和65.2，均篇IF 7.24；发明专利5项(授权4项)。