外阻对三室MFC产电性能和Cu迁移特性的影响

构建一种新型的三室微生物燃料电池（microbial fuel cells，MFCs）对重金属Cu污染的土壤进行修复，研究不同外阻条件下MFC的产电性能和土壤中Cu的迁移去除情况.结果表明，当外接电阻从100Ω增大到1000Ω时，三室MFC的输出电压从0.1V提高到0.4V，最大功率密度从1.10W/m³降低到0.71W/m³，且阴极极化现象也随外阻增大而更加显著.装置运行63d后，MFC外接电阻越大，近阳极土壤区的Cu的去除率越高，外阻为1000Ω的MFC近阳极土壤区的Cu去除率达到39.7%.通过改进欧共体标准（BCR）连续提取法分析重金属的形态，发现乙酸可提取态和可还原态为Cu迁移的两种主要形态.此外，土壤的性质也发生变化，pH值呈现由阳极到阴极逐渐升高的趋势，而电导率则相反.阴极电极的扫描电镜（SEM）和X射线衍射（XRD）结果也表明部分迁移到阴极的Cu（Ⅱ）被还原成单质Cu.

Influence of external resistance on the bioelectricity generation and the migration of Cu in a three-chamber microbial fuel cell

In this study, a novel three-chamber microbial fuel cell (MFC) was constructed in the soil contaminated with Cu, the performance of bioelectricity generation and the migration of Cu in MFC with different external resistance conditions were investigated. The results revealed that the output voltage of the three-chamber MFC increased from 0.1V to 0.4V with the external resistance increased from 100Ω to 1000Ω, and the maximum power density decreased from 1.10W/m³ to 0.71W/m³. The phenomenon of cathode polarization was more obvious with the increase of external resistance. Experimental results showed that the electricity generated by MFCs could significantly facilitate metal removal, the removal efficiency of Cu in soil near anode reached 39.7% with the external resistance of 1000Ω after 63 days. Meanwhile, the modified Community Bureau of Reference (BCR) sequential extraction procedure was applied to characterize the five fractions of heavy metals. It showed that acid extractable and reducible fractions were the two main fractions of Cu migration. In addition, the pH increased gradually from the anode to the cathode in Cu-contaminated soil while the conductivity was opposite. The results of the scanning electron microscope (SEM) and X-ray diffraction (XRD) demonstrated that the Cu (Ⅱ) which partially migrated to the cathode was reduced to the metal copper.