微生物燃料电池（MFCs）性能的影响因素及苯酚为底物的研究

【作者】 刘雷；

【导师】 张恩仁；

【作者基本信息】 扬州大学 ， 物理化学， 2013， 硕士

【摘要】 随着社会的发展、人口的激增,人类对能源的需求与日俱增,随之而来的是资源枯竭和环境污染问题。在人类寻求低碳生活与可持续发展道路时,越来越重视废物的再利用,微生物燃料电池(Microbial Fuel Cells, MFCs)正是一门符合这种理念的前言技术。MFCs是利用微生物作为生物催化剂,将储藏在有机物中的化学能转化为电能的装置。然而就目前来说MFCs仍处于实验研究阶段,要将MFCs用于实际需要克服诸多瓶颈。本文主要针对MFCs性能的影响因素、阳极溶液的pH调控及难降解物质——苯酚的利用等三个方面的内容进行深入研究,具体内容如下：一、MFCs性能的影响因素研究实验过程中分别考察底物的浓度、放电水平、阳极面积及离子交换膜面积对MFCs性能的影响。增加MFCs的底物浓度能够延长放电时间、增加产电量,但不利于底物库伦效率的提高。提高MFCs的放电水平可以缩短放电时间、增加产电量,提高底物的库伦效率,但前提是MFCs的生物膜性能优越,允许大电流通过；电极面积越大,电池极化现程度越小；内阻越小,输出功率越大。增加阳极面积及离子交换膜面积有利于内阻的减小、产电量的增加、底物库伦效率的提高。二、MFCs阳极溶液pH的变化研究及调控对比MFCs在开路与闭路状态下阳极溶液的pH变化,发现pH的变化与电路的电流变化密切相关,且电流越大,pH下降的速率越快。通过阳极溶液的滴定曲线计算阳极溶液中产生氢离子的量,与外电路中通过的电子数量相比较,发现两者比值趋近于0.84。这表明微生物催化底物产生的氢离子只有不到20%通过离子交换膜到达阴极,完成剩余电荷转移的是溶液中其它的阳离子。阳极溶液pH的降低,将严重影响微生物的催化活性,降低MFCs的底物去除率和库伦效率。因此,为了控制溶液pH的变化,实验向阳极溶液中分别加入碳酸钙固体、碳酸氢钠固体、氢氧化钠溶液或增大缓冲体系浓度等方式来调控溶液的pH。通过对比,发现各种方式都不同程度地提高了MFCs的性能,其中加入氢氧化钠的方法最具操作性。三、苯酚和醋酸钠为混合底物的MFCs性能研究实验通过控制苯酚和醋酸钠的配比模拟工业废水,考察不同配比的混合物对MFCs产电性、苯酚和COD去除率的影响。实验结果表明,微生物在降解底物时具有选择性,结构简单的小分子化合物醋酸钠容易被分解,表现出苯酚和COD去除率的不同步性；同时,醋酸钠的加入能够显著地提高MFCs的输出功率。当以苯酚为单一底物时,MFCs处于闭路状态对苯酚的除去效果优于开路状态。PCR-DGGE条带的聚类分析表明,不同底物的MFCs系统,经长时间的运行后,阳极系统中微生物群落结构会发生很大的变化。更多还原

【Abstract】 With the development of society and the rapid increase in population, more and more energy is demanded by human each passing day, which brings resource depletion and environmental pollution problems. For low carbon life and the road of sustainable development, then human pay more and more attention to waste, Microbial fuel cells (MFCs) are the one in line with the concept of this preface technology. MFCs are novel environmental friendly energy device which converts chemical energy contained in organic compounds to electrical energy by using microorganism as a biocatalyst. For now, MFCs are still in the experimental research stage, many bottlenecks will be needed to overcome before they are used in catual. This paper mainly studies the three aspects:the factors affecting the performance of MFCs, the regulation of pH anode solution, the degradation of difficult substance-phenol. And the specific contents as follows:Part one:Study on the influencing factors of MFCs performanceThe concentration of the substrate, the level of discharge, the area of the anode and ion exchange membrane were investigated to impact on MFCs performance during the experiment. Increasing substrate concentration of MFCs could prolong the discharge time, increase production capacity, but it was not conducive to the substrate to improve the efficiency of coulomb efficiency. Improving the discharge level of MFCs could short the discharge time, increase production capacity, improve the efficiency of substrate in coulomb efficiency, but the premise was the superior performance of bio-film MFCs, allowed high current through. And the electrode area was huge, polarization phenomenon was not serious; the smaller internal resistance, the larger output power. Increased anode area and ion exchange membrane area were good for decreasing resistance, increasing production of electricity, producing substrate coulomb efficiency.Part two:MFCs anode solution pH change research and managementComparison of MFCs pH changed in the open and closed state of the anode solution, found that current changes and circuit of pH were closely related to the current, and the greater current, the faster decline rate of pH. Combination of the anode solution titration curve calculation the quantity of anode produce hydrogen ions in the solution, with the electrons in the external circuit, found that the ratio reaching0.84. This shows that the microbial catalysis substrates to produce less than20%of the hydrogen ions only by ion exchange membrane to the cathode, and complete the rest of the charge transfer were other cations in the solution.The lower pH of anode solution had seriously affected the catalytic activity of microorganisms, so to improve the efficiency of MFCs substrate removal rate and coulomb, we need to control the change of the pH value of the solution. Calcium carbonate anode solid, sodium bicarbonate, sodium hydroxide solution and increasing the concentration of buffer system were added to the experiments, which had effectively improved the MFCs performance. To compair the comprehensive evaluation, we found that hydroxide solution method in sodium was the most practical.Part three:Phenol and sodium acetate as the mixed substrate of MFCs’performance researchPhenol was often contained in industrial wastewater and could be used as MFCs’substrate, during the experiment different proportions easy decomposition of sodium acetate was mixed as the substrate, too. We investigaed the ralatingship between the mixed substrate and the electrical, the influence of the phenol and the COD removal rate. Experimental results showed that when the microorganisms on the degradation of the substrate had a selective, simple structure of the small molecular compound sodium acetate was easy decomposed, show the asynchronism of phenol and the COD removal rate. At the same time, the addition of sodium acetate could significantly increase the output power of MFCs. When using phenol as a single substrate, MFCs in the closed state of phenol removal effect were good.PCR-DGGE bands of clustering analysis showed that different substrates of MFCs system, through the long time running, greated changes would happen in the anode system’s microbial community structure.更多还原