重金属离子在微生物燃料电池阳极中的行为

发布时间：2018-10-26 18:04

【摘要】：微生物燃料电池(Microbial fuel cells, MFCs)是一种可以将有机物的化学能直接转化为电能的新型技术。重金属离子对MFCs的产电性能具有重要影响,例如对阳极产电微生物的毒性作用,对阳极过程的促进作用,以及参与阴极过程等。本文研究了MFCs型生物毒性传感器对含汞废水生物毒性的检测方法,研究了铜离子和镍离子在微生物燃料电池阳极中迁移、转化和去除等过程。MFCs型生物毒性传感器可以作为水质安全事故的预警装置,本文利用MFCs型生物毒性传感器对含汞废水的生物毒性进行检测,结果表明：汞离子浓度与MFCs输出电压的抑制率成正相关,相关系数为0.9776；当外电阻为25-35Ω时,最低检测限为0.5mg/L,最大抑制率为21.74%。外电阻越小,MFCs检测生物毒性的灵敏度也越高,响应时间越短,检测限越小；然而,外电阻太小,则不利于MFCs的长期稳定运行。分析认为,MFCs生物毒性检测器检测生物毒性时,最佳外电阻选择范围为0.5 R内-0.7 R内。以铜离子(Cu~(~(2+))/Cu标准电极电位为+0.34 V)为研究对象,研究了铜离子在MFCs阳极对产电性能的影响,其形态转化、迁移及去除机制。当铜离子浓度低于19.44 mg/L时,MFCs输出电压高于空白组,结果表明低浓度铜离子可以促进MFCs的产电性能。当铜离子浓度在20～100 mg/L时,产电性能开始下降,但MFCs输出电压稳定在0.5 V以上。铜元素质量分布研究结果表明,15-21%的铜离子在生物膜上形成铜单质,60～75%的铜离子与溶液中的硫离子和磷酸盐生成硫化铜和磷酸铜沉淀；铜离子在MFCs的阳极被去除,几乎没有迁移到阴极室。还原生成的铜单质加强了电子传递而提高了MFCs的产电性能。铜离子的去除机理主要为生物吸附和化学沉淀。以镍离子(Ni~(2+)/Ni标准电极电位为-0.23 V)为研究对象,研究了其在MFCs中阳极的行为,包括去除效率,产电性能,迁移和分布。结果表明：镍离子也可以通过MFCs的阳极去除。在镍离子浓度为2.93-8.80 mg/L时,可促进MFCs的电压输出；在镍离子浓度为2.93～58.67 mg/L时,外电阻为5000Ω时,MFCs的输出电压稳定在0.6 V以上；镍离子的去除机理主要为化学沉淀过程(质量分数高达为93%),包括阳极沉淀比例为75.5%,阴极沉淀比例为15.0%左右。
[Abstract]:Microbial fuel cell (Microbial fuel cells, MFCs) is a new technology which can directly convert the chemical energy of organic matter into electric energy. Heavy metal ions have important effects on the electrical properties of MFCs, such as toxicity to anodic electroproducing microorganisms, promotion of anodic processes, and participation in cathodic processes. In this paper, the method of detecting the biological toxicity of mercury-containing wastewater by MFCs biosensor was studied, and the migration of copper and nickel ions in the anode of microbial fuel cell was studied. MFCs biosensor can be used as an early warning device for water quality safety accidents. In this paper, the biotoxicity of mercury-containing wastewater was detected by MFCs biosensor. The results show that there is a positive correlation between mercury ion concentration and the inhibition rate of MFCs output voltage, and the correlation coefficient is 0.9776; When the external resistance is 25-35 惟, the minimum detection limit is 0.5 mg / L, and the maximum inhibition rate is 21.74. The smaller the external resistance, the higher the sensitivity of MFCs in detecting biotoxicity, the shorter the response time and the smaller the detection limit. However, if the external resistance is too small, it is not conducive to the long-term stable operation of MFCs. It is concluded that the optimal range of external resistances for the detection of biotoxicity by MFCs biotoxicity detector is within 0. 5R-0. 7R. The effect of copper ion (Cu~ (2) / Cu standard electrode potential of 0.34V) on the electrical properties of MFCs anode and its morphology transformation, migration and removal mechanism were studied. When the concentration of Cu ~ (2 +) is below 19.44 mg/L, the output voltage of MFCs is higher than that of the blank group. The results show that the low concentration of Cu ~ (2 +) can promote the electrical properties of MFCs. When the concentration of copper ion is 20 ~ 100 mg/L, the electrical properties begin to decrease, but the output voltage of MFCs is more than 0.5 V. The results of mass distribution of copper elements show that 15-21% copper ions form copper elements on biofilm, and 6075% copper ions form copper sulphide and copper phosphate precipitates with sulfur ions and phosphates in solution. Copper ions were removed from the anode of MFCs and hardly migrated to the cathode chamber. The reduced copper increases the electron transfer and improves the electrical properties of MFCs. The removal mechanism of copper ion is mainly biosorption and chemical precipitation. The anode behavior of nickel ion (Ni~ (2) / Ni standard electrode potential of -0.23 V) in MFCs was studied, including removal efficiency, electrical properties, migration and distribution. The results show that nickel ion can also be removed by anode of MFCs. When the concentration of nickel ion is 2.93-8.80 mg/L, the output voltage of MFCs can be promoted, and the output voltage of MFCs is more than 0.6 V when the concentration of nickel ion is 2.93 mg/L and the external resistance is 5000 惟. The removal mechanism of nickel ion is mainly chemical precipitation process (mass fraction as high as 93%), including anodic precipitation ratio of 75.5% and cathodic precipitation ratio of 15.0%.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;TM911.45

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