Study On Electrode Optimization In Single-chamber Microbial Fuel Cells

Microbial fuel cell(MFC) is a novel device which can convert chemical energy contained in organic matter into electrical energy through the catalytic reaction of microorganisms. MFC, a new way of treating wastewater, can treat organic wastewater while producing electricity. In the sudy of MFC technology, there are still many problems to be solved. At present, low power output and high cost are supposed to the two major problems that hinder the commercialization and practical application of MFC. Moreover, the electrode materials are the key factors in the electricity generation and cost of MFC. Therefore, it is essential to improve the MFC’s performance by modification of electrode materials.In this paper, on the basis of the single-chamber microbial fuel cell, the materials of graphene and polyaniline were used to modify the anode and cathode of MFC, respectively. And then, the effects of the electricity generation of MFC after modification of the cathode and anode were discussed. On the basis of the modification of the cathode and anode, MFC was first used to remove the oxytetracycline(OTC). The results of this paper are summarized as follows:(1)The graphene modified carbon cloth electrode(G/CC) and polyaniline modified carbon cloth electrode(PANI/CC) and polyaniline-graphene modified carbon cloth(PANI-G/CC) were obtained by adopting impregnating, and they were tested by LSV and EIS technology. The results showed the electrode modified by polyaniline-graphene had better catalytic activity and lower activation resistance. The electrodes were used as MFC cathode. The maximum power density of MFC with PANI-G/CC cathode was 8.48mW/m2, 3.2 times and 1.7 times larger than that of MFC with CC cathode and G/CC cathode, respectively. The results showed that polyaniline-graphene modified cathode can improve the electricity production of MFC.(2)The Co/CC electrode, Co-G/CC electrode, Co-PANI/CC electrode and Co-PANI-G/CC electrode were obtained through the methode of layers of assembling of the sulfonated phthalocyanine cobalt(CoPcSO4) modified CC electrodes, G/CC electrodes, PANI/CC electrode and PANI-G/C electrode, respectively. And then, they were tested by LSV technology, which showed Co-PANI-G/CC electrode had best oxygen reduction electrode catalytic performance. The maximum power density of MFC with Co-PANI/CC cathode was 32.2mW/m2, 1.8 times, 1.7 times and 6.1 times larger than that of MFC with Co-G/CC cathode, Co-PANI/CC cathode and Co/CC cathode. It indicated that modifing cathode with the CoPcSO4 as cobalt catalyst, united with polyaniline-graphene was a simple and effective method of modification to improve the MFC production performance.(3)The PANI-G/CC electrode was used as MFC anode. The maximum power density of MFC with PANI-G/CC cathode was 84.2mW/m2, 2.5 times and 1.7 times larger than that of MFC with CC anode and G/CC anode, respectively. The resistance of MFC with PANI-G/CC anode was 266 Ω, 34% and 21% lower than that of MFC with CC anode and G/CC anode, respectively. It indicated that the anode modified by polyaniline and graphene can decrease the resistance of MFC, and significantly improve the production performance of MFC.(4)The single-chamberMFC were built by PANI- G/CC anode, Co-PANI-G/CC cathode, with different concentrations of OTC(25 mg/L, 50 mg/L, 100 mg/L, 200 mg/L) and 500 mg/L glucose as fuel. The effect of the addition of different concentration of OTC on the production performance of single chamber-MFC and OTC degradation were studied. The results showed that the production performance of MFC and degradation performance of OTC gradually declined with the increase of concentration of OTC. But when the concentration of OTC was less than 50 mg/L, the production performance is relatively good, and after running 5 days, the removal rate of OTC and COD were over 90%, respectively. The degradation process of OTC in single chamber-MFC conformed to the first-order reaction kinetics, with R2 above than 0.95. The results showed that it was feasible using the single chamber-MFC to treat the mixed OTC wastewater and to generate electricity. MFC technology offers a new way to treat OTC wastewater.