光致空穴界面提升生物阳极输出性能机制及应用

发布时间：2018-02-27 17:35

  本文关键词： 微生物燃料电池 光辅助阳极 输出电流 界面电子传递 不锈钢材料　出处：《浙江工商大学》2017年硕士论文　论文类型：学位论文

【摘要】：能源短缺和环境污染是当今中国面临的两大难题。微生物燃料电池(Microbial fuel cells,MFCs)利用具有跨膜电子传递能力的电活性微生物,将氧化有机质所产生的电子进行定向传输,从而实现化学能与电能的转化,是一项有望协同解决能源短缺与环保污染问题的新兴废水处理技术。但目前输出功率低下与工程材料欠缺严重限制了MFCs的进一步发展。基于此,本文利用电极表面修饰光催化材料所形成的光致空穴界面,提高生物膜/阳极界面电势差,加速界面电子传递速率及微生物呼吸代谢速率,从而获得更大的输出功率;同时选用易工程放大的不锈钢毡为阳极基底材料,考察光致空穴提升其输出性能机制和工程放大的可行性。论文的主要内容和结果如下:1、利用电沉积法成功将α-Fe_2O_3修饰到石墨阳极外侧,修饰后的阳极光电流为0.74 A m-2(-0.2 V偏压)。首次以该电极构建光电微生物燃料电池(PMFC),其启动时间比常规MFC缩短一半,最大输出电流提升2倍以上(8.4Am-2)。在开闭光条件切换下,输出电流响应迅速,表明光致空穴界面即时加速了生物膜/阳极界面电子传递速率。此外,PMFC生物阳极的生物膜生长速率和主要产电微生物Geobacter的丰度(87%)也均显著高于普通MFC,表明光致空穴界面对阳极生物膜形成具有长期促进作用,且能定向筛选并富集电活性微生物。2、考察了不同光催化材料、电极基底及生物侧修饰物对于光致空穴界面效果的影响。结果表明不同光催化材料(CdS、TiO_2和α-Fe_2O_3)修饰PMFCs所获电流的提升倍数之间具有显著差异,PMFCα-Fe_2O_3和PMFC TiO_2的最大输出电流分别提升2.0和1.7倍,而PMFCdS提升倍数最大可达2.8倍,但随着CdS光催化材料的失效其输出电流会回落至MFC同等水平。光致空穴界面同样可以加速不锈钢基底阳极表面的生物膜形成速率,并提升输出功率,最大电流提升倍数达6倍以上。生物界面修饰碳颗粒和聚苯胺可显著影响MFCs输出性能,其最大输出电流分别为9.2和4.6 A m-2,但光致空穴界面仍提升输出电流2.0倍。综上推测光催化材料和电极基底材料是影响光致空穴界面效果的主控因子。3、首次在工程材料不锈钢电极上分别构建了碳微粒薄膜、聚苯胺、中性红、亲水性基团和铁氧化物五种改性层,并探究了其对于MFCs输出性能的影响。结果表明碳微粒薄膜和聚苯胺修饰的阳极具有优异的比表面积和生物兼容性,从而分别提升MFCs(3 A m-2)输出电流至13 A m-2和9 A m-2。中性红基团修饰通过加速生物膜与电极间的电子传递,提高输出电流至4.5 Am-2。亲水性基团修饰则通过提升微生物在电极表面的成膜速率,提高输出电流至6 A m-2。基于此,本研究以α-Fe_2O_3作为光催化层、三维不锈钢毡作为基底、碳微粒负载作为生物层修饰技术首次设计了一种高性能的复合三维不锈钢毡光辅助阳极,最大面积电流密度在光激发下从26 A m-2提升至46 Am-2,体积电流密度达20.9 kAm-3,性能在已有报道的文献中位列前列。4、将光致空穴界面机理拓展应用至微生物燃料脱盐池(PMDC)。PMDC最大输出电流为8 A m-2,随脱盐室盐度的降低(内阻增大)而迅速下降,当电流低于0.5 Am-2以后脱盐率达96%以上,而相同运行时间下MDC脱盐率低于50%。综上表明,光辅助修饰是一种使用寿命长久、作用效果显著、操作简洁环保的生物阳极改性技术,在废水处理、产电、合成、产氢等各种生物电化学领域具有广阔的应用前景。
[Abstract]:Energy shortage and environmental pollution are two major problems in current Chinese face. Microbial fuel cell (Microbial fuel, cells, MFCs) using the electrical activity of microorganisms with transmembrane electron transfer ability, electron generated oxidized organic matter of directional transmission, so as to realize the transformation of chemical energy and electrical energy, is an emerging collaboration is expected to the wastewater treatment technology to solve the energy shortage and environmental pollution problems. But the output power is low and the lack of engineering materials has seriously restricted the further development of MFCs. Based on this, this paper induced interfacial holes formed by surface modification of photocatalytic material of light, improve the biological membrane / anode interface potential at the interface, accelerate the electron transfer rate and microbial respiration the metabolic rate, so as to get higher output power; at the same time using easy scale-up of stainless steel felt as anode substrate materials, light induced hole to enhance its investigation The feasibility and mechanism of the output performance of the amplification of the project. The main contents and results are as follows: 1, using electrodeposition alpha -Fe_2O_3 modified graphite anode side, the anodic photocurrent modified 0.74 A m-2 (-0.2 V bias). For the first time to construct the electrode photoelectric microbial fuel cell (PMFC), the start half the time shorter than the conventional MFC, the maximum output current increase more than 2 times (8.4Am-2). In the opening and closing switch under light conditions, the output current rapid response, show the light induced hole interface instant accelerated biofilm / anode interface electron transfer rate. In addition, the abundance of PMFC Bio anode biofilm growth rate and the main power generation microbial Geobacter (87%) were significantly higher than that of conventional MFC, show the light induced interfacial holes with long-term effect on the anode biofilm formation, and directional screening and enrichment of electroactive microbial.2, tested different photocatalytic 鏉愭枡,鐢垫瀬鍩哄簳鍙婄敓鐗╀晶淇�楗扮墿瀵逛簬鍏夎嚧绌虹┐鐣岄潰鏁堟灉鐨勫奖鍝�.缁撴灉琛ㄦ槑涓嶅悓鍏夊偓鍖栨潗鏂，

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