微生物燃料电池阳极生物膜的保护与功率输出的优化研究
发布时间：2019-01-22 11:27
【摘要】：微生物燃料电池(MFC)是一种利用电活性微生物氧化降解有机小分子,将化学能转化为电能的电化学装置。近年来,关于MFC的理论基础研究已取得了巨大的进展,然而其实际应用,特别是污水处理,还受到了极大的限制。一方面,当溶液中氧含量增大时,MFC阳极的厌氧电活性微生物的生物电化学活性会受到严重抑制甚至完全失去。因此,MFC技术难以与传统的好氧污水处理技术相融合。另一方面,MFC的输出不稳定,单个MFC容易产生功率骤降,而且串联MFC电池组容易发生电压反转,严重降低MFC的功率输出。针对上述问题,本论文一方面采用物理交联的聚乙烯醇(PVA)水凝胶对电活性微生物膜进行保护,以提高其耐氧性能;另一方面开发具有高电容的多孔碳泡沫(CF)材料作为MFC的阳极,以消除MFC的功率骤降和电压反转,提高MFC的功率输出。第一部分以炭黑修饰的不锈钢网作为阳极,在其上生长电活性微生物膜形成生物阳极;接着采用液氮冷冻/解冻物理交联的PVA对生物阳极进行包裹固定,制备水凝胶微生物阳极。扫描电子显微镜(SEM)形貌表征显示,液氮冷冻/解冻制备的PVA凝胶内部呈现规则的管状结构。MFC全电池性能测试显示,基于PVA水凝胶生物阳极的MFC可产生的最大电流密度为1.40 mA cm-2,功率密度为1200 mW m-2,与未包裹凝胶的不锈钢网电极的产电性能相近。生物阳极的耐氧性能测试显示,在曝纯氧的条件下,水凝胶生物阳极的电活性没有受到很大影响,以其构建的MFC的功率输出也基本保持不变;而没有水凝胶包裹的生物阳极,其电活性则急剧降低,这说明水凝胶生物阳极具有优异的耐氧性能。水凝胶生物阳极的耐氧性能主要归功于PVA水凝胶降低了氧气扩散速率,阻碍了氧气向电活性生物的扩散。第二部分采用高温炭化三聚氰胺泡沫制备了柔性炭泡沫(CF)。CF具有较大的孔隙率和孔隙结构,有利于电活性微生物的生长。以900℃炭化的厚度为4 mm的碳泡沫(简称CF-900-4)作为阳极,可产生4.2 mA cm-2的电流密度。基于CF-900-4阳极和空气阴极的组成的MFC,其功率密度高达3100 mW cm-2。此外,CF具有优异的机械性能,能够替代传统刚性的炭基材料,为MFC的实际应用提供了可能。第三部分研究了电容型电极对MFC的功率骤降和其在串联时产生的电压反转现象的影响。经过测试发现CF-900不仅是一种性能优异的MFC阳极材料,还是一种出色的电容材料。充放电测试结果显示CF-900的比电容值高达111 F g-1。将CF-900-4与空气阴极组装成MFC后发现单个电池不会发生功率骤降现象;MFC在串联时也不会发生电压反转。因此,电容型的材料可以优化MFC的功率输出。
[Abstract]:Microbial fuel cell (MFC) is an electrochemical device which uses electroactive microorganisms to oxidize and degrade small organic molecules and convert chemical energy into electric energy. In recent years, great progress has been made in the theoretical research of MFC. However, its practical application, especially sewage treatment, has been greatly restricted. On the one hand, when the oxygen content in the solution increases, the bioelectrochemical activity of the anaerobic-active microorganism of MFC anode will be seriously inhibited or even completely lost. Therefore, MFC technology is difficult to integrate with the traditional aerobic wastewater treatment technology. On the other hand, the output of MFC is unstable, the power drop is easy to occur in a single MFC, and the voltage reversal is easy to occur in the series MFC battery pack, which seriously reduces the power output of MFC. To solve the above problems, on the one hand, the physical crosslinked polyvinyl alcohol (PVA) hydrogel was used to protect the electroactive microbial membrane in order to improve its oxygen resistance. On the other hand, the porous carbon foam (CF) with high capacitance is developed as the anode of MFC to eliminate the power drop and voltage reversal of MFC, and to improve the power output of MFC. In the first part, carbon black modified stainless steel mesh was used as anode, on which electroactive microbial membrane was grown to form biological anode. Then the hydrogel microbial anode was prepared by encapsulating and fixing the biological anode with liquid nitrogen freezing / thawing physical crosslinked PVA. Scanning electron microscopy (SEM) (SEM) analysis showed that the PVA gel prepared by liquid nitrogen freezing / thawing had a regular tubular structure. The maximum current density of MFC based on PVA hydrogel biological anode is 1.40 mA cm-2, power density is 1200 mW m-2, which is similar to that of uncoated stainless steel mesh electrode. The oxygen resistance test of the biological anode showed that the electroactivity of the hydrogel biological anode was not greatly affected under the condition of pure oxygen exposure, and the power output of the constructed MFC remained basically unchanged. However, the electrochemical activity of the biological anode without hydrogel encapsulation decreased sharply, which indicated that the hydrogel biological anode had excellent oxygen resistance. The oxygen resistance of hydrogel biological anode is mainly attributed to the decrease of oxygen diffusion rate by PVA hydrogel, which hinders the oxygen diffusion to electroactive organisms. In the second part, the flexible carbon foam (CF). CF) was prepared by high temperature carbonized melamine foam, which has large porosity and pore structure, which is beneficial to the growth of electrically active microorganisms. The current density of 4 mm carbon foam (CF-900-4), which was carbonized at 900 鈩，
本文编号：2413170
[Abstract]:Microbial fuel cell (MFC) is an electrochemical device which uses electroactive microorganisms to oxidize and degrade small organic molecules and convert chemical energy into electric energy. In recent years, great progress has been made in the theoretical research of MFC. However, its practical application, especially sewage treatment, has been greatly restricted. On the one hand, when the oxygen content in the solution increases, the bioelectrochemical activity of the anaerobic-active microorganism of MFC anode will be seriously inhibited or even completely lost. Therefore, MFC technology is difficult to integrate with the traditional aerobic wastewater treatment technology. On the other hand, the output of MFC is unstable, the power drop is easy to occur in a single MFC, and the voltage reversal is easy to occur in the series MFC battery pack, which seriously reduces the power output of MFC. To solve the above problems, on the one hand, the physical crosslinked polyvinyl alcohol (PVA) hydrogel was used to protect the electroactive microbial membrane in order to improve its oxygen resistance. On the other hand, the porous carbon foam (CF) with high capacitance is developed as the anode of MFC to eliminate the power drop and voltage reversal of MFC, and to improve the power output of MFC. In the first part, carbon black modified stainless steel mesh was used as anode, on which electroactive microbial membrane was grown to form biological anode. Then the hydrogel microbial anode was prepared by encapsulating and fixing the biological anode with liquid nitrogen freezing / thawing physical crosslinked PVA. Scanning electron microscopy (SEM) (SEM) analysis showed that the PVA gel prepared by liquid nitrogen freezing / thawing had a regular tubular structure. The maximum current density of MFC based on PVA hydrogel biological anode is 1.40 mA cm-2, power density is 1200 mW m-2, which is similar to that of uncoated stainless steel mesh electrode. The oxygen resistance test of the biological anode showed that the electroactivity of the hydrogel biological anode was not greatly affected under the condition of pure oxygen exposure, and the power output of the constructed MFC remained basically unchanged. However, the electrochemical activity of the biological anode without hydrogel encapsulation decreased sharply, which indicated that the hydrogel biological anode had excellent oxygen resistance. The oxygen resistance of hydrogel biological anode is mainly attributed to the decrease of oxygen diffusion rate by PVA hydrogel, which hinders the oxygen diffusion to electroactive organisms. In the second part, the flexible carbon foam (CF). CF) was prepared by high temperature carbonized melamine foam, which has large porosity and pore structure, which is beneficial to the growth of electrically active microorganisms. The current density of 4 mm carbon foam (CF-900-4), which was carbonized at 900 鈩，
本文编号：2413170
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