非缓冲微生物燃料电池产电性能强化研究

发布时间：2018-05-11 05:53

本文选题：微生物燃料电池(MFC) + 非缓冲　；参考：《江南大学》2017年硕士论文

【摘要】：微生物燃料电池(Microbial fuel cell,MFC)可同步实现能源转换及废弃物处置,是环境技术研究热点。目前,实验室小型MFC运行过程中,一般需要加入PBS缓冲液或NaHCO3溶液,用以维持一定的离子强度和pH值,保障体系高效稳定的运行。然而,未来MFC在污水处理领域的大规模应用需要在无缓冲条件下进行,因为添加缓冲盐会增大运行成本,且可能造成出水富营养化等环境问题。非缓冲MFC体系中,阳极表面不断产生并积累质子(H+),出现“阳极酸化”现象,严重限制产电微生物的生长和活性。因此,欲进一步提高非缓冲MFC体系产电能力,使其更具实用价值,解决“阳极酸化”问题是关键。本课题通过外加短期碱性调控和阳极液回用的方法,缓解了非缓冲空气阴极MFC体系的“阳极酸化”问题,强化了体系产电性能。主要研究内容与结果如下:(1)利用碱处理阴离子交换树脂(AER)中和阳极液中积累的H+,以此缓解产电初期“阳极酸化”对产电微生物生长和活性的限制。实验结果表明,运行过程中,以KCl溶液为阳极液的KCl-MFC体系的pH值从7.09下降到5.82,出现了“阳极酸化”现象。将碱处理AER置于KCl阳极液中,在运行中前四天内,AER表面的OH-被完全释放,此后阳极液pH值先快速降低到5.87后回升到6.66,并保持稳定。两个周期的短期碱性干预,促进了阳极表面电化学活性Geobacter的增殖,提高了阳极生物膜的电化学活性,最终KCl-AER-MFC体系的最大功率密度(Pmax)由307.5 mW/m2显著提高到542.8 m W/m2。(2)通过对非缓冲KCl阳极液初始pH值进行短期碱性调控,缓解了“阳极酸化”对体系运行初期阳极表面产电微生物增殖和生物膜形成的影响,最终提高了MFC体系的产电性能。实验确定了阳极液初始pH值调控的最佳方案,即在5个运行周期内将阳极液初始pH值调为9。KCl-pH9-MFC体系短期的阳极液初始pH值调控,促进了电化学活性微生物Geobacter在阳极表面的繁殖,其相对丰度由59.01%升高到75.12%,阳极电化学活性显著提高,电子生成效率提高。因此,在H+扩散限制的条件下,空气阴极利用电子产生OH-的效率相对较高,提高了阳极液的整体pH值,最终体系的Pmax由321.04 mW/m2显著提高到536.38 mW/m2。短期的碱性调控建立了阳极液pH值与阳极生物膜产电活性之间新的平衡关系,使得体系较高产电性能具有可持续性。(3)通过对非缓冲阳极液进行一定比例的回用,加快阳极反应产生的自生缓冲物质(H2CO3和HCO3-)的积累,消除非缓冲MFC体系的“阳极酸化”现象。KCl-R-MFC体系阳极液前3个周期pH值快速升高,第4周期阳极液起始pH值已经达到8.19并随着运行周期的增多而缓慢上升。阳极液中相应无机碳(IC)浓度也由15.85 mmol/L升高到59.10 mmol/L。经过多个周期的回用后,KCl-R-MFC体系的Pmax由322.91 mW/m2增加到527.22 m W/m2,与PBS-MFC体系相近(523.74 mW/m2)。
[Abstract]:Microbial fuel cell (MFCs), which can realize energy conversion and waste disposal synchronously, is a hotspot of environmental technology research. At present, in order to maintain certain ionic strength and pH value, it is necessary to add PBS buffer or NaHCO3 solution in the process of small-scale MFC operation in laboratory to ensure the efficient and stable operation of the system. However, the future large-scale application of MFC in the field of sewage treatment needs to be carried out without buffer, because adding buffer salt will increase the operation cost and may cause environmental problems such as eutrophication of effluent. In the non-buffer MFC system, proton H ~ (2 +) is produced and accumulated on the anode surface, and the phenomenon of "anodic acidification" occurs, which seriously limits the growth and activity of electroproducing microorganisms. Therefore, in order to further improve the power generation capacity of non-buffer MFC system and make it more practical, the key to solve the problem of "anodic acidification" is to solve the problem of anodic acidification. In this paper, the problem of "anodic acidification" of non-buffer air cathode MFC system was alleviated by adding short-term alkaline control and anodic solution reuse, and the electrical performance of the system was strengthened. The main contents and results are as follows: (1) neutralizing H accumulation in anion exchange resin (AER1) by alkali treatment, so as to alleviate the limitation of "anodic acidification" on the growth and activity of electroproducing microorganisms in the early stage of electricity production. The results showed that the pH value of KCl-MFC system with KCl solution as anodic solution decreased from 7.09 to 5.82 during the operation, and the phenomenon of "anodic acidification" appeared. After alkaline treatment of AER in KCl anodic solution, OH- on the surface of KCl was completely released within four days before operation. After that, the pH value of the anodic solution decreased rapidly to 5.87 and then increased to 6.66, and remained stable. The short-term alkaline intervention of two cycles promoted the proliferation of electrochemical activity of Geobacter on anode surface and enhanced the electrochemical activity of anode biofilm. In the end, the maximum power density (Pmax) of KCl-AER-MFC system was significantly increased from 307.5 mW/m2 to 542.8 MW / m2). The effect of "anodic acidification" on the proliferation of electroproducing microorganisms and biofilm formation on the anode surface at the initial stage of the system was alleviated, and the electrical properties of the MFC system were finally improved. The optimal control scheme of initial pH value of anodic solution was determined, that is, the initial pH value of anodic solution was adjusted to the initial pH value of 9.KCl-pH9-MFC system for a short period in five operating cycles, which promoted the propagation of electrochemical active microorganism Geobacter on the anode surface. The relative abundance increased from 59.01% to 75.12%, the electrochemical activity of anode and the efficiency of electron generation were improved significantly. Therefore, under the condition of H diffusion limitation, the efficiency of using electron to produce OH- in the air cathode is relatively high, and the overall pH value of the anodic solution is increased. The Pmax of the final system is increased from 321.04 mW/m2 to 536.38 MW / m2. The new equilibrium relationship between the pH value of the anode solution and the electrochemical activity of the anode biofilm was established by the short-term alkaline control, which made the system have the sustainability of higher electrical properties. (3) by reusing the non-buffer anode solution in a certain proportion, the pH value of the anode solution and the electroproduction activity of the anode biofilm were reused. The accumulation of endogenous buffer substances (H2CO3 and HCO3-) from anodic reaction was accelerated, and the "anodic acidification" phenomenon in non-buffer MFC system was eliminated. The pH value of anodic solution in KCl-R-MFC system increased rapidly during the first three cycles. The initial pH of the anodic solution reached 8.19 in the fourth cycle and increased slowly with the increase of the operating cycle. The concentration of inorganic carbon in anodic solution also increased from 15.85 mmol/L to 59.10 mmol / L. After several cycles of reuse, the Pmax of KCl-R-MFC system increased from 322.91 mW/m2 to 527.22 MW / m2, which was similar to that of PBS-MFC system (523.74 MW / m2).
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.45

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