电活性生物膜生长过程中电荷与传质阻抗的变化规律  

Charge and mass transfer impedance through different growth phases of anode-respiring biofilm

作　　者：侯俊先[1] 刘中良[1] 李艳霞[1] 周宇[1] 

机构地区：[1]北京工业大学环境与能源工程学院教育部传热强化与过程节能重点实验室,北京100124

出　　处：《科学通报》2016年第33期3616-3622,共7页Chinese Science Bulletin

摘　　要：电活性生物膜因为能直接向胞外产生电子,将生物能直接转化成电能,所以近年来已经成为国际领域内的研究热点.在电活性生物膜内部,一方面存在着复杂的生物电化学过程,另一方面微生物及生物膜生长又涉及复杂的质量传递过程.本文针对电活性生物膜不同生长阶段的质量传递损失和电荷传递损失展开研究,以期找到在不同时期内其产能的限制因素,这将对于电活性生物膜性能的改善具有至关重要的作用.本研究结果表明,80 h时,电荷传递阻抗占总内阻的99.8%.因此在电活性生物膜运行初期,电荷传递阻抗成为限制其产能的主要因素.随着运行时间的增长,电荷传递阻抗的比例不断下降,430和460 h时分别为86.9%和72.9%.运行到500 h后,电荷传递阻抗的比例下降到33.1%.然而此时,传质阻抗的占比上升到38.6%.因此当电荷性生物膜逐渐成熟时,电荷阻抗和传质阻抗共同成为其产能的限制因素.因此在电活性生物膜不同生长阶段,采用不同的方法来降低其对应的内阻对提高产电性能至关重要.Electrochemically active biofilms（EABs） respire in a unique form in which they utilize solid external materials as terminal electron acceptors for their metabolism. When microorganisms use anodes of microbial fuel cells（MFCs） or microbial electrolysis cells（MECs） and so on for respiration, they are called ＂anode-respiring biofilm（ARB）＂. There were complex bio-electrochemical and mass transfer processes as ARBs grew in bioreactors. Currently, very little real time data is available characterizing charge and mass transfer impedance during ARB formation. In the present study, ARB was cultivated in a three-electrode bioreactor for about one month. We measured charge and mass impedance to find out the limiting factors for power output through different phases of ARB growth. Electrochemical impedance spectroscopy（EIS） was also used to investigate the charge and mass transfer impedance, while Cyclic Voltammetry（CV） was used to measure the electrochemical activities. CV and EIS were all measured at five different times（80, 280, 430, 460 and 500 h） during ARB formation. Current density curve shows that power output of ABR increased as biofilm grew and it goes up from 0.35 A m-2 at 280 h to 9.41 A m-2 at 500 h. CVs also illustrated that the electron transfer rate of ABR increased greatly over time. We can observe that the limiting current density from CVs has a similar trend with the current curve of ARB which demonstrates that the current generation ability of ABR increases during biofilm formation. Impedance value of anode-respiring biofilm displays that ohmic resistance is around 25 ？ showing little change. However, charge transfer impedance goes a downward trend. They are 12500, 2346, 996, 520 and 132 ？ respectively at these five different time which drops sharply with biofilm growing. The reason is that the microorganisms inside ARB increases significantly especially operating after 460 h, which increases the substrate utilization rate and electron transfer rate of ABR greatly. Howe

关 键 词：电活性生物膜 微生物燃料电池 电化学 传质阻抗 电荷阻抗 

分 类 号：TM911.45[电气工程—电力电子与电力传动]