Promoting removal of copper from sediment and production of bioelectricity by sediment microbial fuel cells using tea extracts

Abstract

In a sediment microbial fuel cell (SMFC) in which both the cathode and the anode are embedded in the sediment, copper is removed from the anode zone by its migration to the cathode. However, the removal of copper in an SMFC is often limited by poor mass transfer in the sediment environment. Tea extracts are rich in tea polyphenols, which are antioxidizing and transfer electrons. Adding tea extract to the electrodes of an SMFC can not only increase the efficiency of reduction of copper but also minimize the internal resistance of the SMFC, increasing its power output and the migration of copper. The results herein reveal that (1) the peak redox current of tea extract that was obtained using 50 % ethanol as the extractant was 60 μA, which was 1.39 and 1.69 times those obtained using DI water and 75 % ethanol, respectively; (2) adding tea extract reduced the internal resistance of the SMFC by 12.5 %; (3) the SMFC to whose anode tea extract was added removed 70.7 % of copper and had a maximum power density of 19.45 mW/m3, which was 1.66 times that of the SMFC without the tea extract. The SMFC with added tea extract can potentially be used to remediate heavy metal-contaminated sediment.