【作者】 许凤玲；

【导师】 侯保荣； 段继周；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋化学， 2009， 博士

【摘要】 海洋电活性微生物(又称电活性生物膜,electroactive biofilms, EABs)是自然界存在的一类功能性微生物,能够将代谢有机物产生的电子直接或间接传递给电极,人们对其在环境中的广泛性及其在生物防腐、生物能源和生物修复中的应用正在开展广泛的研究。本论文着眼于海洋天然生物膜的电活性,从微生物腐蚀和微生物燃料电池的角度,考察研究了海洋天然生物膜对316L SS腐蚀行为的影响,发现海洋天然生物膜能抑制316L SS腐蚀,系统研究了海洋生物膜与石墨等电极的电子传递过程,提出了电活性生物膜(EABs)与电极间的电子传递机制,并初步研究了海洋电活性生物膜在微生物燃料电池(MFCs)中的应用。对附着天然海洋生物膜的316L SS研究发现,生物膜使316L SS电位正移了500mV (vs. Ag/AgCl)。316L SS表面附着海洋生物膜后,其孔蚀电位由原来的50mV增加到540mV,孔蚀敏感性降低;同时,海洋生物膜的附着导致316L SS的阻抗增加,由此,我们明确提出海洋生物膜能够抑制316L SS腐蚀的发生。进一步研究了生物膜抑制腐蚀发生的可能机理。循环伏安实验表明,海洋生物膜与不锈钢电极之间存在电子传递过程。扫描电镜(SEM)及能谱(EDS)分析发现有钙盐的沉积生成。通过以上结果我们提出了生物膜对腐蚀的抑制机制假设,即在电极与电活性海洋生物膜间发生了电子传递,海洋生物膜能够将电子传递给不锈钢,316L SS作为电子接受体受到保护。为进一步研究天然海洋生物膜的这种电活性,我们选择不会发生腐蚀的惰性电极材料石墨,玻碳,碳纸电极验证生物膜的电活性。首次考察了天然海洋生物膜对石墨电极和玻碳电极的开路电位变化的影响,结果显示随电极在天然海水中浸泡时间,石墨电极正移50mV vs. Ag/AgCl,玻碳电极正移了300 mV (vs. Ag/AgCl)。与316L SS相似,三种电极的变正趋势相同,都经历了三个阶段,即初始缓慢变正期,随后的指数变正期和以后的稳定期,此与生物膜在固体表面形成的趋势相似。伏安曲线及阻抗实验结果表明,在石墨,玻碳和碳纸电极材料表面附着海洋生物膜后,电流密度增加,电荷转移电阻减小,说明生物膜与电极间存在电子传递,并能加速电子传递过程,不同材料表面生物膜的电活性能力由大到小为石墨>316L SS>碳纸>玻碳。进一步研究了海洋沉积物-海水生物膜微生物燃料电池,初步建立了相应的电极材料和微生物燃料电池结构。我们选择石墨阳极和石墨阴极或316L SS阴极组装海泥沉积物(阳极区)和海水(阴极区)MFC,316L SS代替石墨做阴极最大输出电量达9mW.m-2,约为后者的2倍。两种MFC输出电流和功率密度随时间的延长而增加的趋势相同,都可以分为三个阶段,即初期的缓慢增加阶段,中期的指数增长阶段,后期的平台稳定期阶段。这也与生物膜在固体表面形成的趋势相似。此研究也说明优化316L SS表面性质筛选活性海洋生物膜用于MFC有其潜在的应用价值。更多还原

【Abstract】 Marine electro-active biofilms (electrochemical active biofilms, EABs) are kinds of functional biofilms in nature that can transfer the electrons produced by metabolizing organism to electrodes. The application of the EABs in inhibition corrosion, biosources and bioremediation has been studied extensively.In this paper, the influence of the marine natural biofilms on the corrosion of 316L SS was studied firstly. And the results showed that the marine biofilms can inhibit the corrosion of 316L SS. And then we systemically studied the electrons transfer process between EABs and electrodes and proposed the mechanism of electrons transfer between EABs and electrodes. And the application of EABs in MFCs was studied.The OCP (open circuit potential) of 316L SS ennobled 500mV vs. Ag/AgCl. The marine biofilms increased the pitting potential of 316L SS from 0.05V to 0.54V and increased the impedance. And the Electron microscopy (EMS) and Energy-Dispersive Spectroscopy (EDS) found there was no corrosion production on the 316L SS surface. So we made the decision that the marine biofilm can inhibit corrosion of the 316L SS. The cyclic voltammograms (CV) showed that the marine biofilms accelerated the electron transfer, catalyzed the cathode reaction. So we presented the inhibition mechanism of marine biofilms on 316L SS. The marine biofilms have electrochemical active to transfer electron between the biofilms and 316L SS. And the 316L SS can accept electron transferred by marine biofilms to avoid the corrosion.And then we used the graphite, glasscarbon and carbon paper electrodes to validate the EABs.The ennoblement of glasscarbon and graphite OCP in seawater were firstly studied. The glasscarbon ennobled positively 300mV vs. Ag/AgCl, and the graphite ennobled positively 50mV vs. Ag/AgCl. And the ennoblement trends of the two electrodes were in common with 316L SS and were agreed with the trends of the biofilm’s growth: the first ennoblement slowly, exponent period, and then the platform period.The CV and EIS showed that the marine biofilms attached on graphite, glasscarbon and carbon paper electrodes catalyzed the cathodic reduction effectively and decreased the impedance that showed that the marine biofilms were EABs and can transfer electrons. The ability of the catalysis descended according to the sequence graphite, 316L SS, carbon paper and glasscarbon.We farther studied the marine deposition-seawater Microorganism fuel cells (MFCs). The MFCs were set up with graphite as anode and graphite or 316L SS as cathode. The stainless steel electrodes gave current densities 2 times higher than graphite. And the trends of the power and current increasing were agreed with the trend of the biofilm’s growth. So it is important significance to enhance the 316L SS surface quality and screen electroactive biofilms to be used in MFC.更多还原