【作者】 郭伟；

【导师】 孙剑辉；

【作者基本信息】 河南师范大学 ， 环境科学， 2014， 博士

【摘要】 近年来兴起和快速发展的微生物燃料电池(Microbial fuel cell, MFC)技术能直接利用废水中多种有机物作为燃料，在降解污染物的同时直接收获电能，是一种革命性的废水处理工艺，受到国内外学者的广泛关注。目前限制MFC实际应用的一个关键问题就是输出功率较低。在影响其功率输出的诸多因素中，阳极因为影响微生物的吸附和生长代谢，以及电子从微生物到电极之间的传递而被认为是一个关键因素。目前广泛采用的商业化的碳基材料存在比表面积有限，电化学活性较小等不利因素。利用能增加电极比表面积和促进电子传递的某种电活性材料对碳材料表面进行修饰是一种行之有效的解决方法。本文从产电和废水处理两方面着手，探索借助阳极修饰的方法提高MFC产电性能的可行性；并以典型偶氮染料甲基橙为目标污染物，考察甲基橙在MFC中的脱色效果及同步产电性能。论文主要研究内容和成果如下：(1)用柠檬酸盐还原氯金酸的方法制备粒径约为20nm的金纳米粒子。首次利用层层组装技术将金纳米粒子修饰到碳纸电极表面，并利用紫外-可见光谱监测了薄膜的规律生长。循环伏安和电化学交流阻抗实验表明：纳米金修饰碳纸电极较空白碳纸电极表现出更好的电化学行为，包括更大的电活性表面积，更快的电子转移速率及更小的界面电子传递阻力。相比空白碳纸阳极组装的MFC，利用纳米金修饰碳纸阳极组装的MFC达到最大输出功率346mW m-2，提高了50%，启动时间为175h，缩短了36%。实验结果表明：层层组装技术是将纳米金修饰到碳纸电极上的一种简单有效的方法，而且利用该修饰电极能够有效提高微生物燃料电池的产电性能。(2)利用化学还原氧化石墨烯(Graphene Oxide, GO)的方法制备并表征了石墨烯(Graphene, GR)。采用层层组装技术将石墨烯修饰到碳纸电极表面，并探讨该方法能否有效提高MFC的电能输出和对甲基橙的高效去除。循环伏安和电化学交流阻抗实验表明：石墨烯修饰碳纸电极较空白碳纸电极表现出更好的电化学行为。扫描电子显微镜结果显示：修饰电极表面的粗糙度增加，有利于更多的细菌附着在阳极表面。相比空白碳纸阳极组装的MFC，利用石墨烯修饰电极作为阳极的MFC达到最大输出功率368mWm-2，提高了51%，启动时间为180h，缩短了31%。阳极和阴极极化曲线表明：两种反应器的阴极电压之间没有明显区别，而阳极电压存在明显区别，这说明提高微生物燃料电池能量输出的关键是石墨烯修饰阳极，而不是阴极。同时，相比于空白阳极MFC，石墨烯修饰阳极MFC在实现更高能量输出的同时，还实现了更高效的甲基橙去除，脱色率提高11%，COD去除率提高16%。该研究为提高微生物燃料电池的产电性能和甲基橙同步脱色提供了一种简单有效的方法。(3)采用所构建的双室方形微生物燃料电池处理甲基橙模拟废水。在进水甲基橙浓度为50-800mg L1、共基质（葡萄糖）浓度为0-2.0mg L1的条件下，系统考察了MFC对甲基橙的脱色效果和同步产电的影响。在MFC以甲基橙-葡萄糖为混合燃料连续工作6个月后，通过生物多样性分析揭示了阳极生物膜微生物组成的基本信息。结果发现：在一定浓度范围内，阳极室中加入的甲基橙对微生物燃料电池产电有积极的促进作用。当使用1g L-1葡萄糖为单一燃料时，MFC的最大输出电压为565mV，当在阳极液中添加甲基橙浓度分别为50、100、200、300和500mg L1时，MFC的最大输出电压分别提高至658、640、629、617和605mV。从脱色方面看，甲基橙在MFC中可以实现加速脱色，相比于开路情况(相当于普通厌氧反应器)，反应8h后甲基橙在MFC中的脱色率提高了57%；在葡萄糖浓度一定的条件下，随着甲基橙负荷的增加，脱色效率随之下降。另外，研究发现共基质的存在对甲基橙的高效脱色和同步产电是必须的。在所研究共基质浓度范围内，共基质浓度越大，脱色效率和COD去除效率越高，同时输出电压也越大。而在无共基质存在的条件下，8h内MFC对300mg L-1甲基橙的脱色率仅为7.5%，最大输出电压仅为140mV。454-高通量测序揭示了阳极生物膜的微生物种群基本信息，经NCBI网站比对的测序结果表明：经过长时间的驯化，阳极生物膜已经优化出了对甲基橙具有降解能力的Bacteroidia、Desulfovibrio和Trichococcus及其适合产电的Geobacter两大菌群。更多还原

【Abstract】 In recent years, microbial fuel cell (MFC) is a rapidly developed technology that can generateelectricity with simultaneous organic matter removal from domestic and industrial wastewaters. As a kindof revolutionary way for wastewater treatment, MFC has become the focus of researchers all over the world.However, the relatively low power output was considered as one of the main obstacles for its furtherapplication. Amongst many factors affecting the performance of MFC, the anode, which had greatinfluence on the growth and activities of microbes as well as on the electron transfer rates, was consideredas one of the key limiting factors. Traditionally, carbon materials which have been widely used as anodehave their drawbacks such as limited surface area and relatively small electrocatalytic activity. To increasethe anode performance, one promising approach is the modification of anode surface with certainelectroactive materials that can enhance the actual accessible area for bacteria to anchor and affect theinterfacial electron transfer resistance and subsequently improve the anode performance. The mainconclusions in the paper are as follows:(1) The gold colloids with20nm diameter were prepared via the reduction of HAuCl4by trisodiumcitrate. The gold nanoparticles (Au NPs) modified carbon paper electrode was successfully constructed bylayer-by-layer assembly technique for the first time. UV-vis spectroscopy was used to monitor the regularlayer growth of the {PEI/Au}10multilayer. The results of cyclic voltammetry (CV) and electrochemicalimpedance spectroscopy (EIS) in Fe(CN)63-/4-solution demonstrated that the Au NPs modified carbon paperelectrode exhibited better electrochemical behavior than the bare carbon paper electrode, includingrealtively high electroactive surface areas, increased electron transfer rate and decreased interfacial electron transfer resistance. A two-chambered MFC equipped with the modified anode achieved a maximum powerdensity of346mW m-2and a start time for the initial maximum stable voltage of175hours, which wererespectively50%higher and36%shorter than the corresponding values of the MFC with the unmodifiedanode. All the results indicated that the LBL assembly Au NPs-based modification on the anode was asimple but efficient method to incorporate Au NPs onto carbon paper electrodes and promoted theelectricity generation of MFC.(2) Graphene was synthesized by chemically reduction of graphene oxide (GO) to grapheme (GR). Weaimed to investigate whether modification of carbon paper (CP) anode with graphene (GR) vialayer-by-layer assembly technique is an effective approach to promote the electricity generation and methylorange (MO) removal in MFC. Using cyclic voltammetry (CV) and electrochemical impedancespectroscopy (EIS), the GR/CP electrode exhibited better electrochemical behavior. SEM results revealedthat the surface roughness of GR/CP increased, which was favorable for more bacterial to attach to theanode surface. The MFC equipped with GR/CP anode achieved a stable maximum power density of368mW m-2under1000external resistance and a start time for the initial maximum voltage of180hours,which were respectively51%higher and31%shorter than the corresponding values of the MFC with blankanode. The anode and cathode polarization curves revealed negligible difference in cathode potentials butobviously difference in anode potentials, indicating that the GR modified anode other than the cathode wasresponsible for the performance improvement of MFC. Meanwhile, compared with MFC with blank anode,11%higher decolorization efficiency and16%higher the COD removal rate were achieved in MFC withGR modified anode during electricity generation. This study might provide an effective way to modify theanode for enhanced electricity generation and efficient removal of azo dye in MFC.(3) Research on the decolorization of methyl orange (MO) simulated wastewater in the two-chambered cubic microbial fuel cells. Systemly studied the bioelectricity generation and decolorizationof MO in the anode chamber of MFC in wide concentration ranges of MO (from50to800mg L1) and ofco-substrate glucose (from0to2.0g L1). The microbial communities on the anode were revealed after theMFC was operated continuously for more than6months using MO-glucose mixtures as fuel. The resultsshowed that the added MO played an active role in production of electricity. The maximum voltage outputswere565,658,640,629,617and605mV for the1g L-1glucose with0,50,100,200,300and500mg L1MO, respectively. Moreover, accelerated decolorization efficiency of MO realized in MFC, increased57%compared to the open-circuit control during8hours. Co-substrate was necessary for the simultaneouselectricity generation and azo dye decolorization. Decolorization efficiency and COD removal rate bothincreased with the increase of the co-substrate concentration. The decolorization efficiency of300mg L-1MO in MFC without co-substrate was only7.5%，the maximum voltage output was only140mV。454high-throughput pyrosequencing revealed the microbial communities. Geobacter genus known to generateelectricity was detected. Bacteroidia class, Desulfovibrio and Trichococcus genus, which were most likelyresponsible for degrading methyl orange, were also detected.更多还原