Enhancing the Efficiency of P-Smfcs in Degrading Phenanthrene by Modifying the Anode with Carbon Nanomaterials

Abstract

In plant-sediment microbial fuel cells (P-SMFCs), the anode is the main biochemical reaction area. In this study, different carbon nanomaterials (graphenes (GNs), carbon nanotubes (CNT), hydroxylated-carbon nanotubes (CNT-OH), and carboxylated-carbon nanotubes (CNT-COOH)) were used to modify the anode of the P-SMFCs to explore enhancements degradation of Phe. The devices operated for 131 days, CNT-COOH modified P-SMFCs (P-CNT-COOH) had a shorter start-up period and higher voltage during the stable operation stage. The voltage of P-CNT-COOH during the stationary phase was about 250 mV higher than that of the traditional configuration SMFC. The voltage of P-CNT-COOH had the highest degrading that was 67.5% of Phe, which was 1.25 times higher than the P-CNT. . The voltage and Phe removel of P-CNT-COOH was higher than CNT-COOH(no plant SMFC), but CNT(no plant SMFC) was higher than P-CNT. The anode modified with P-CNT-COOH became enriched with more small-molecule volatile fatty acids (VFAs) (e.g., acetic acid) and degrading bacteria (e.g., Thiobacillus and Desulfobulbus)  attributed to the higher hydrophily. The removal of Phe was positively correlated with dehydrogenase activity (DHAA). The high metabolic abundance of Metabolism of cofactors and vitamins in P-SMFCs may have played an important role in the degradation of Phe.

Keywords: plant-sediment microbial fuel cell (P-SMFC), phenanthrene, microbial degradation, carbon nanotubes, hydrophily