单室微生物燃料电池阳极碳布的电化学修饰研究

发布时间：2018-03-31 03:20

本文选题：微生物燃料电池　切入点：电化学氧化法　出处：《华南理工大学》2014年硕士论文

【摘要】：微生物燃料电池利用微生物，将可再生的生物质能（废水或者其它废弃物）转化为电能，是一种洁净的可再生能源技术。本文以生活污水为处理对象，以电化学氧化法修饰的碳布作为阳极，以铂负载量为0.5mg/cm2的碳布作为阴极构建单室空气阴极微生物燃料电池(SCMFCs)。通过扫描电镜(SEM)和X射线光电子能谱(XPS)详细表征了阳极碳布的表面生物膜和表面官能团的分布情况，揭示了电化学氧化法提高SCMFCs性能的直接原因；细致考察了阳极碳布的处理方式（电化学氧化法和浸泡法）、乙酸钠浓度、离子强度和pH值等参数对SCMFCs产电性能的影响，完成各参数的系统优化。首先，详细研究了阳极碳布经三种电解质溶液（混酸、硝酸铵、硫酸铵）修饰后对SCMFCs产电性能的影响。与未改性碳布相比，，经修饰后的三种阳极碳布均显著提高了SCMFCs的输出电压和功率密度，其中混酸（硫酸和硝酸的混合液）的修饰效果最为明显。其次，通过SEM和XPS对阳极碳布的表面生物膜和表面官能团的分布情况进行详细表征，揭示了电化学氧化法提高SCMFCs性能的直接原因。阳极表面的电化学修饰有助于增加不饱和碳原子以及氧化性碳原子的数量，显著提高电化学活性比表面积，从而提高微生物在电极表面的附着速率和生物膜含量。第三，以混酸、硝酸铵和硫酸铵作为改性溶液，分析了两种不同修饰方法：化学浸泡法和电化学氧化法对阳极碳布表面形貌特征和元素组成的影响。相比于化学浸泡法，电化学氧化法能够有效提高碳布表面的粗糙度，增多表面刻蚀和沟痕，增大碳布表面积，因而有效促进了微生物在表面的附着；此外，电化学氧化法能使碳布表面产生更多亲水官能团，提高碳布表面的浸润性，上述变化可能是电化学氧化法提高SCMFCs性能的直接原因。最后，分别以混酸和硝酸铵作为修饰阳极碳布的电解质溶液，考察了乙酸钠浓度、离子强度、pH值和混酸浓度对SCMFCs产电性能的影响。研究结果表明：在底物乙酸钠浓度为3g/L、氯化钠浓度为100mM、pH值分别为8（混酸）和7.5（硝酸铵）、混酸浓度为1/6倍浓酸时SCMFCs能获得最大产电性能。
[Abstract]:Microbial fuel cell is a clean renewable energy technology, which uses microorganisms to convert renewable biomass energy (waste water or other wastes) into electric energy.In this paper, a single chamber air cathode microbial fuel cell (SCMFCs) was constructed by using carbon cloth modified by electrochemical oxidation as anode and carbon cloth loaded with platinum as 0.5mg/cm2 cathode.The distribution of biofilm and functional groups on the surface of anodic carbon cloth was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), and the direct reason for improving the performance of SCMFCs by electrochemical oxidation was revealed.The effects of the treatment methods of anodic carbon cloth (electrochemical oxidation and immersion method, sodium acetate concentration, ionic strength and pH value) on the electrical properties of SCMFCs were investigated in detail.Firstly, the effects of three kinds of electrolyte solutions (mixed acid, ammonium nitrate, ammonium sulfate) on the electrical properties of SCMFCs were studied in detail.Compared with the unmodified carbon cloth, the three kinds of modified anodic carbon cloth significantly increased the output voltage and power density of SCMFCs, and the modification effect of the mixed acid (the mixture of sulfuric acid and nitric acid) was the most obvious.Secondly, the distribution of biofilm and functional groups on the surface of anodic carbon cloth was characterized by SEM and XPS in detail, which revealed the direct reason of improving the performance of SCMFCs by electrochemical oxidation.The electrochemical modification of the anode surface can increase the number of unsaturated carbon atoms and oxidizing carbon atoms, and increase the specific surface area of electrochemical activity, thus increasing the adhesion rate of microorganisms and the content of biofilm on the electrode surface.Thirdly, using mixed acid, ammonium nitrate and ammonium sulfate as modified solutions, the effects of two different modification methods, chemical immersion method and electrochemical oxidation method, on the surface morphology and elemental composition of anodic carbon cloth were analyzed.Compared with chemical immersion method, electrochemical oxidation method can effectively improve the roughness of carbon cloth surface, increase surface etching and groove marks, increase carbon cloth surface area, thus effectively promote the adhesion of microorganisms on the surface.Electrochemical oxidation can make the surface of carbon cloth produce more hydrophilic functional groups and improve the wettability of carbon cloth surface. These changes may be the direct reason for the electrochemical oxidation method to improve the performance of SCMFCs.Finally, the effects of sodium acetate concentration, ionic strength pH value and mixed acid concentration on the electrical properties of SCMFCs were investigated by using mixed acid and ammonium nitrate as electrolyte solutions respectively.The results show that when the substrate concentration of sodium acetate is 3 g / L, the pH value of sodium chloride is 100 mMN = 8 (mixed acid) and 7.5 (ammonium nitrate), and the concentration of mixed acid is 1 / 6 times concentrated acid, SCMFCs can obtain the maximum electrical performance.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM911.4;O646.54

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