表面功能化碳纳米管促进微生物燃料电池界面电子传递机理研究

发布时间：2018-06-04 18:29

本文选题：微生物燃料电池 + 腐败希瓦氏菌　；参考：《西南大学》2017年硕士论文

【摘要】：微生物燃料电池(Microbial fuel cell,MFC)是一种利用微生物的新陈代谢作用将有机燃料或废弃物中的化学能转化为可输出电能的装置,它是微生物技术和电化学技术相结合的一种新兴能源系统。除了提供可直接利用的电能外,MFC在污水处理、顽固有机污染物降解、有害金属离子回收与利用等环境工程领域也具有广泛的应用前景。目前,由于MFC功率密度低、启动速度慢和生产成本较高等限制因素,这项技术尚处于实验室研究阶段,离规模化应用还有一定的距离。在MFC中,阳极生物电催化性能是主要的限制因素之一,然而它又在很大程度上受限于阳极产电微生物与电极间的界面电子传递效率。因此,对阳极材料结构和化学性质的优化,促进细菌与电极的快速电子传递,是提升MFC性能的关键手段。碳纳米管(Carbon nanotubes,CNTs)作为一种性能优异的一维纳米材料,被广泛应用于电化学等领,尤其作为MFC阳极材料,更是发挥了其自身特有的性能。在MFC阳极室中,产电微生物通过厌氧氧化有机底物将电子输出到胞外并交付给阳极,因此,阳极接受电子的能力直接影响MFC的产电性能。而CNTs由于其高导电性和良好的生物兼容性,能够加强产电微生物和电活性分子与电极间的接触,并快速的将接收的电子进行转移,作为阳极材料能够提高电池性能。基于此,本文从设计不同表面性质的阳极材料出发,以腐败希瓦氏菌(Shewanella putrefaciens CN32)为产电菌株,研究它们对S.putrefaciens CN32阳极产电能力和胞外电子传递效率的增强作用,并从胞外电子传递所涉及的产电菌株和电极材料两方面系统地研究MFC阳极胞外电子传递机制。主要研究内容和结果如下:(1)首先采用浓酸酸化法处理CNTs,成功制备了羧基化的碳纳米管。实验结果显示,酸化后的CNT_b/CC阳极能够获得最大平台电流密度为1.41±0.06 A m~(-2),相比于原始的CNTa/CC(1.09±0.02 A m~(-2))增加了29%,表明酸化之后的CNTb/CC阳极具有更高的MFC电流输出能力。并且改善CNTs的表面性质之后,最大功率密度达到472 mW m~(-2),高于原始的CNTa/CC阳极(272 mW m~(-2))的1.7倍。从二者水溶液分别静置3h之后的照片可以看出,CNTs经酸化处理后亲水性得到了提高,并且SEM实验结果证实细菌在酸化后的CNTs上生长量高于未经任何处理的CNTs表面。初步断定,MFC阳极材料表面亲水性的改变能够促进细菌生物膜在电极表面的生长和附着,从而提高MFC的界面电子传递速率。(2)其次,采用物理吸附法制备了碳纳米管-磷钼酸/碳毡(CNT-PMo/CF)复合材料,并将其用作S.putrefaciens CN32 MFC的阳极材料,利用MFC全池测试阳极的产电性能,分析其对阳极生物膜生长和生物电催化性能的影响。接触角实验数据表明,CNTs经PMo修饰之后,亲水性得到明显提高。比较不同CNT/PMo比例的复合材料发现,当CNTs与PMo的质量比为1:2时,所制备的CNT-PMo/CF复合材料具有最小的界面电荷传递阻抗,从而具有最好的生物电催化性能,当其作为MFC阳极时的最大功率密度为1235 mW m~(-2),相比CNT/CF阳极(190 mW m~(-2))MFC提高了6.5倍,比单独的CF阳极(99 mW m~(-2))MFC提高12倍,证明了由阳极材料的独特表面性质及较快的界面电子传递传递速率对增强MFC阳极生物电流产生的重要作用。(3)最后,采用化学反应法合成了碳纳米管-离子液体(CNT-IL)纳米复合材料,将该纳米复合材料应用于接种S.putrefaciens CN32的MFC阳极并系统分析了其增强MFC阳极生物电催化的机制。带正电的IL与酸化后带负电的CNTs结合,所形成的CNT-IL纳米复合材料也是带正电的,而我们所用的S.putrefaciens CN32表面是显负电性的。同时,研究发现,当CNT和IL的比例达到1:90的时候,该复合材料中N的含量最高,这就使得S.putrefaciens CN32所分泌的黄素类电子介体FMN能够更多的聚集在CNT-IL b纳米复合材料阳极表面,而这些电子介体可以在生物膜内介导短距离、快速的间接电子传递过程。另外,由于IL和CNT同时都具有的高导电性,可以确保黄素类电子介体在该复合阳极材料界面上实现快速的电化学氧化反应,从而协同地增强生物膜内内源性电子介体介导的直接电化学过程。CNT-IL b复合阳极的MFC获得了1076±85 mW m~(-2)的最大功率输出密度,是单独CNT阳极的3倍。在所制备的CNT-IL纳米复合材料中,IL的修饰使得该纳米复合材料相比于单独的CNT具有更大的比表面积、更好的亲水性、导电性和生物相容性,使得二者在增强阳极生物膜直接电化学过程中展现出独特的协同作用,首次提出了一种基于IL功能化CNTs的策略能够增强MFC阳极生物电催化的协同作用,为MFC的实际应用打开新思路。
[Abstract]:Microbial fuel cell (MFC) is a device that uses the metabolism of microbes to convert chemical energy in organic fuel or waste into output power. It is a new energy system combined with microbiological technology and electrochemical technology. In addition to providing direct use of electricity, MFC is at the sewage site. In the field of environmental engineering, such as the degradation of refractory organic pollutants, the recovery and utilization of harmful metal ions and other environmental engineering fields, the technology is still in the stage of laboratory research because of the low power density of MFC, slow start speed and high production cost. This technology is still in a certain distance from the large-scale application. In the MFC, it is positive. The electrocatalytic performance of polar organisms is one of the main limiting factors. However, it is largely limited to the electron transfer efficiency at the interface between the anode producing microorganism and the electrode. Therefore, the optimization of the structure and chemical properties of the anode materials and the rapid electronic transmission of the bacteria and electrodes are the key means to improve the performance of MFC. Carbon nanotubes (C Arbon nanotubes, CNTs, as a one dimensional nanomaterial with excellent performance, is widely used in electrochemistry collar, especially as a MFC anode material, it has its own unique performance. In the MFC anode chamber, the electric microorganism output the electron to the anode through the anaerobic oxidizing organic substrate, so the anode accepts electricity. The ability of the MFC is directly affected by the ability of the subunit. And because of its high conductivity and good biocompatibility, CNTs can strengthen the contact between the electric microorganism and the electroactive molecules and the electrode, and quickly transfer the received electrons to the anode material to improve the battery energy. Based on this, this paper designs the different surface properties. The anode material, taking the Shewanella putrefaciens CN32 as the producing strain, studies the enhancement of the S.putrefaciens CN32 anode production capacity and the exo electron transfer efficiency, and systematically studies the MFC anode extracellular electron transfer machine from two aspects of the electric producing strain and electrode material involved in the extracellular electron transfer. The main research contents and results are as follows: (1) the carboxylation of carbon nanotubes was successfully prepared by the treatment of CNTs with concentrated acid acidification. The experimental results showed that the maximum platform current density after acidified CNT_b/CC anode was 1.41 + 0.06 A m~ (-2), and increased by 29% compared to the original CNTa/CC (1.09 + 0.02 A m~ (-2)), indicating acidification The post CNTb/CC anode has a higher MFC current output capacity. And after improving the surface properties of CNTs, the maximum power density is 472 mW m~ (-2), higher than the original CNTa/CC anode (272 mW m~ (-2)). The photo of the CNTs after the acidification of the two water solution shows that the hydrophilicity of the CNTs is improved after acidification. The results of EM experiment confirmed that the growth of the bacteria on the acidified CNTs was higher than that of the CNTs surface without any treatment. It was preliminarily concluded that the change of the hydrophilicity of the surface of the MFC anode material could promote the growth and attachment of the bacterial biofilm on the surface of the electrode and thus improve the electron transfer rate of the interface of MFC. (2) Secondly, the physical adsorption method was used to prepare the carbon nanofiltration. The rice tube phospho Molybdate / carbon felt (CNT-PMo/CF) composite was used as the anode material of S.putrefaciens CN32 MFC. The effect of the anode on the growth of anode biofilm and the bioelectrocatalytic properties of the anode was analyzed by the full pool of MFC. The contact angle experimental data showed that the hydrophilicity of CNTs was greatly improved after the CNTs was modified by PMo. The composite materials with different CNT/PMo ratios have found that when the mass ratio of CNTs to PMo is 1:2, the prepared CNT-PMo/CF composites have the smallest interface charge transfer impedance, and thus have the best bioelectrocatalytic performance. The maximum power density of the composite is 1235 mW m~ (-2) when the MFC anode is used as the anode, and is higher than the CNT/CF anode (190 mW m~). It is 6.5 times higher than that of the single CF anode (99 mW m~ (-2)) MFC. It is proved that the unique surface properties of the anode material and the rapid electron transfer rate of the interface have important effect on the enhancement of the biocurrent of the MFC anode. (3) finally, the carbon nanotube ionic liquid (CNT-IL) nanocomposite was synthesized by chemical reaction. The rice composite material was applied to the MFC anode inoculated with S.putrefaciens CN32 and the mechanism of its enhanced MFC anode bioelectrocatalysis was systematically analyzed. The positive IL was combined with the negative CNTs after acidification. The formed CNT-IL nanocomposite was also positive, while the S.putrefaciens CN32 surface we used was negative. Meanwhile, the research of the S.putrefaciens CN32 surface was negative. It is found that when the proportion of CNT and IL reaches 1:90, the content of N is the highest in the composite, which makes the flavin electron medium FMN secreted by S.putrefaciens CN32 can accumulate more on the surface of the CNT-IL B nanocomposite anode, and these electronic mediators can mediate short distance in the biofilm and fast indirect electron transfer. In addition, due to the high conductivity of both IL and CNT at the same time, it can ensure the rapid electrochemical oxidation reaction on the interface of the composite anode material, and thus synergically enhance the MFC of the.CNT-IL B composite anode mediated by the endogenous electronic mediator in the biofilm and obtain 1076 + 85 mW m~ The maximum power output density of (-2) is 3 times that of a single CNT anode. In the prepared CNT-IL nanocomposites, the modification of IL makes the nanocomposites have a greater specific surface area, better hydrophilicity, conductivity and biocompatibility than the separate CNT, which makes the two in the direct electrochemical process of the enhanced anode biofilm. For the first time, a new strategy based on IL functionalized CNTs can enhance the synergism of MFC anode bioelectrocatalysis and open a new idea for the practical application of MFC.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.45

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