Degradation efficiency and mechanism of sulfur-containing azo dye wastewater by microbial fuel cell under different pH conditions
LI Li,, DAI Qin, ZHANG Sai, LIU Hao Key Laboratory of Eco-Environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400045, China
Abstract:Single-chamber air cathode microbial fuel cells (MFC) were constructed to treat the sulfur-containing azo dye wastewater in this study. The effects of initial pH on the MFC performances of electricity production, the removal of azo dyes and sulfide, and electrochemical behavior by anode biofilm were investigated. Moreover, the intermediate products from azo dyes reduction were analyzed by UV-vis, HPLC and LC-MS. The results showed that the anolyte in single-chamber air cathode MFC with acetate as substrate was beneficial for the improvement of power output under neutral conditions. When the pH increased from 5.0 to 9.0, the power generation performance of MFC increased first and then decreased. At neutral pHs, the best power generation performance and target pollutants degradation occurred, followed by weak acidic and alkaline pHs, then over acidic and alkaline pHs. At pH=7.0, the maximum power density of MFC was 24.5 mW·m?2 and the minimum internal resistance was 154.1 Ω. Besides, the highest microbe activity occurred, as well as the highest degradation efficiency of sulfide, azo dyes and COD. The corresponding removal efficiencies of sulfide, azo dyes and COD were 98.40%, 84.60% and 49.56%, respectively. In addition, the CV curves showed that pH played an important role on the redox ability of the anodic bacteria, and the exoelectrogens had the strongest oxidation ability under neutral conditions. 4,4'-diamine biphenyl and 3,4-diaminonaphthalene-1-sulfonic acid were confirmed to be the typical intermediates of congo red degradation, and elemental sulfur, thiosulfate and sulfate were the main products of sulfide oxidation. This study provided a certain technical and theoretical support for the treatment of actual sulfur-containing azo dye wastewater. Key words:microbial fuel cells/ azo dyes/ power generation/ pH/ cyclic voltammetry.
图1单室空气阴极MFC装置示意图 Figure1.Schematic diagram of single-chamber air cathode MFCs
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Key Laboratory of Eco-Environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400045, China Received Date: 2020-04-25 Accepted Date: 2020-07-06 Available Online: 2021-01-13 Keywords:microbial fuel cells/ azo dyes/ power generation/ pH/ cyclic voltammetry Abstract:Single-chamber air cathode microbial fuel cells (MFC) were constructed to treat the sulfur-containing azo dye wastewater in this study. The effects of initial pH on the MFC performances of electricity production, the removal of azo dyes and sulfide, and electrochemical behavior by anode biofilm were investigated. Moreover, the intermediate products from azo dyes reduction were analyzed by UV-vis, HPLC and LC-MS. The results showed that the anolyte in single-chamber air cathode MFC with acetate as substrate was beneficial for the improvement of power output under neutral conditions. When the pH increased from 5.0 to 9.0, the power generation performance of MFC increased first and then decreased. At neutral pHs, the best power generation performance and target pollutants degradation occurred, followed by weak acidic and alkaline pHs, then over acidic and alkaline pHs. At pH=7.0, the maximum power density of MFC was 24.5 mW·m?2 and the minimum internal resistance was 154.1 Ω. Besides, the highest microbe activity occurred, as well as the highest degradation efficiency of sulfide, azo dyes and COD. The corresponding removal efficiencies of sulfide, azo dyes and COD were 98.40%, 84.60% and 49.56%, respectively. In addition, the CV curves showed that pH played an important role on the redox ability of the anodic bacteria, and the exoelectrogens had the strongest oxidation ability under neutral conditions. 4,4'-diamine biphenyl and 3,4-diaminonaphthalene-1-sulfonic acid were confirmed to be the typical intermediates of congo red degradation, and elemental sulfur, thiosulfate and sulfate were the main products of sulfide oxidation. This study provided a certain technical and theoretical support for the treatment of actual sulfur-containing azo dye wastewater.