Abstract：In denitrifying microbial fuel cells (MFCs), the biocathode is the electron donor and nitrate is removed in autotrophic conditions. Reduced graphene oxide modified carbon cloth (rGO-CC), polyaniline modified CC (PANI-CC), and rGO/PANI composite modified CC (rGO/PANI-CC) were prepared, and the electricity and the denitrification performances of MFCs with modified CC as cathodes were evaluated. Scanning electron microscopy analysis revealed that the carbon fibers of rGO-CC and PANI-CC were covered by lamellar rGO and reticular PANI, respectively, while PANI agglomerated on the rGO-covered carbon fibers for rGO/PANI-CC; both of which increased the specific surface area of CC. Cyclic voltammetry tests showed the rGO/PANI-CC had the highest electrochemical activity. The electricity performances of MFCs with rGO-CC, PANI-CC and rGO/PANI-CC as cathodes were improved by 82%, 24% and 41%, and the cathodic denitrification rates were enhanced by 23%, 9% and 13%, respectively. The 16S rDNA sequencing results demonstrated the α-diversity index of electrode-attached microorganisms on modified CC decreased, and the relative abundances of Stappia and Pacacoccus increased.
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