Degradation of thiamphenicol by electroactive biofilm coupled with N-MnO2 modified layer double hydroxides as cathode in microbial fuel cell.

N-doped MnO2 composite NiAl-Layer double hydroxides (N-MnO2@NiAl-LDH) with a ping-pong chrysanthemum like structure was prepared by hydrothermal method as a cathode catalyst in microbial fuel cells (MFCs) in previous study, which demonstrating excellent catalytic performance. This study investigated the power generation performance and the degradation of thiamphenicol (TAP) in N-MnO2@NiAl-LDH-cathode MFC. After the addition of TAP, the maximum power density generated by N-MnO2@NiAl-LDH-cathode MFC was 537.83 mW/m2, which was 5.1 times higher than control MFC. The degradation rate of TAP by N-MnO2@NiAl-LDH-cathode was 81.62 %, which was 2.7 times higher than that of unmodified MFC, the degradation efficiency was significantly improved. Microorganisms were significantly affected by TAP, the abundance of electroactive bacteria (Pseudomonas) decreased, while bacteria related to the biodegradation of TAP (Sphingopyxis, Aridibacter, Norank_ Minicenantales, Petrimonas, etc.) were enriched. The modification of N-MnO2@NiAl-LDH reduced the internal resistance of MFC and accelerated the electron transfer rate, the large specific surface area provided more active sites for electrons, allowing more electrons to be transferred to the cathode. Under the reduction effect of electrons, chlorine atoms of TAP were gradually removed. Meanwhile, a large number of degrading bacteria were attached to the cathode, the dechlorination products underwent C-C bond cleavage and benzene ring opening under the biodegradation of degrading bacteria. The combined effect of electron reduction and microbial oxidation promoted the efficient degradation of TAP.