微生物燃料电池恒电流预培养阳极生物膜分析表征

Analysis and characterization of bioanodes incubated via constant current in a microbial fuel cell

阳极性能是影响微生物燃料电池(Microbial Fuel Cells,MFCs)性能的关键因素之一,同时阳极的接种挂膜过程是影响微生物燃料电池启动效率的关键因素.因此,本课题组提出了预培养阳极作为微生物燃料电池的一种新型阳极的概念,在三电极体系下,通过外加恒定电流预培养阳极,在不同条件下对阳极表面进行电化学选择和生物膜驯化以丰富生物膜结构和厚度.结果表明,阳极的性能与预培养电流大小密切相关,预培养阳极CF-4i(外加4 A·m-2电流密度)通过循环伏安法、塔菲尔曲线、电化学阻抗谱测试,性能好于其他测试组及对照组,装配阳极CF-4i的微生物燃料电池能实现最大功率密度968.20 m W·m-2,是对照组的2.53倍.同时,通过共聚焦显微镜观察发现,生物膜大体分两层,外层的活细胞及内层的死细胞,外层活细胞长在内层死细胞之上.这种结构分布表明,阳极生物膜中的活细胞部分绝大多数都分布于生物膜的外侧,而不是均布于整个阳极生物膜中;同时这也表明不是整个阳极生物膜都具有新陈代谢活性,但死亡的细胞可以继续积累在电极表面附近,活的外层膜负责电流的产生,而内层的死细胞作为一种导电基质.

Anode performance is one of the key factors to MFC（ microbial fuel cells）,at the same time,the inoculation process of anode is the key factor affecting the start-up efficiency of microbial fuel cells.Herein,we propose preincubated anode as a novel concept for the MFCs,which enriching biofilms on the surface of anode surface via electrochemical selection and biofilms acclimatization under different conditions.The results show that the performance of anodes were closely related to the ways of preincubation,while the preincubated anode CF-4 i（ 4 A·m^-2 current density） outperformed the control in cyclic voltammetry,Tafel plot,and electrochemical impedance spectroscopy tests.The maximum power density（ 968.20 mW·m^-2） of the MFC equipped with the anode CF-4 idelivered a 2.53-fold increase over that of the control.Meanwhile,3 D metabolic structure of the biofilms showed all biofilms developed a live outer-layer that covered a dead inner-core. During biofilm development,the live layer reached a constant thickness,whereas dead cells continued to accumulate near the electrode surface,indicating that only the outer-layer of biofilm was responsible for current generation and suggested that the dead inner-layer continued to function as an electrically conductive matrix.