Kinetic study of electron transfer process in methyl orange decolorization by shewanella in MFCs with covalent organic frameworks modified anode.

As a new electrode material for electrochemical systems, covalent organic framework (COF) materials have been gradually applied to bioelectrochemical systems. In our previous study, the COFBTA-DPPD-rGO composite was synthesized via Schiff-base coupling between benzene-1,3,5-tricarbaldehyde (BTA) and 3,8-diamino-6-phenylphenanthridine (DPPD) on reduced graphene oxide (rGO) at room temperature. Here, COFBTA-DPPD-rGO modified MFC anode was used to assist microorganisms to decolorize methyl orange (MO), and the properties of MFCs were studied. The results showed that compared to the unmodified electrode MFC (28 mA m-2, 4.20 mW m-2) the current density and maximum power density of the anode MFC modified by COFBTA-DPPD-rGO (134.5 mA m-2, 21.78 mW m-2) were increased by 380.3% and 423.6%, respectively. The transferred electron number n and charge transfer coefficient α of the modified COFBTA-DPPD-rGO anode (4 and 0.43) compared to the unmodified electrode (2.4 and 0.38) were increased by 67% and 13%, respectively. The decolorization ratio of MO could reach 90.3% at 10 h. Compared with the unmodified electrode MFC (53.0%), the decolorization ratio and kinetic constant of decolorization process were enhanced by 26% and 372%, respectively. Therefore, COFBTA-DPPD-rGO could be a new choice for applying to the MFCs.