Simultaneous enhancement of methylene blue degradation and power generation in a microbial fuel cell by gold nanoparticles

This study examined the effect of positively charged gold nanoparticles [(+)AuNPs] on the enhancement of methylene blue (MB) degradation in a microbial fuel cell (MFC) cathode. Complete MB degradation and a maximum electricity production of 36.56 mW/m² were achieved simultaneously. The MFC performance and MB degradation were found to be strictly dependent on the cathodic conditions, such as N₂ bubbling, air bubbling, and addition of H₂O₂. MB was reduced rapidly under anaerobic conditions, whereas complete oxidative mineralization of MB occurred in the presence of dissolved oxygen (DO) or H₂O₂. (+)AuNPs enhanced the electricity generation in the MFCs involving MB degradation owing to its electron-relay effect. The presence of both (+)AuNPs and H ₂O₂ produced the greatest enhancement in MB degradation. After 5 h, almost all of the MB (98%) and chemical oxygen demand (COD) (96%) had been removed in the presence of (+)AuNPs, whereas only 57.4% of the MB and 40% of the COD had been removed in the absence of (+)AuNPs.