Concurrent performance improvement and biofouling mitigation in osmotic microbial fuel cells using a silver nanoparticle-polydopamine coated forward osmosis membrane

Osmotic microbial fuel cells (OsMFCs) have demonstrated superior electricity production and effluent quality compared to conventional MFCs having ion exchange membranes. However, according to previous OsMFCs studies, inevitable membrane biofouling led to a severe water flux decline during operation. Here, we demonstrated a substantial reduction in biofouling as well as further improvement in current generation by applying a forward osmosis (FO) membrane modified with silver nanoparticles (nAg) that were deposited on a polydopamine (pDA) coated membrane surface. The OsMFC incorporating an nAg-pDA coated FO membrane exhibited less flux decline (22%) than the OsMFC with a pristine membrane (50%) due to an antibacterial ability of nAg. Additionally, the nAg-pDA coated membrane also decreased the internal resistances of the OsMFC by 35% owing to the enhanced hydrophilicity of the membrane surface, resulting in an improvement in power density (12%). The nAg-pDA coated layer was very thin (c.a. 1.06% of total membrane thickness), so caused no adverse flux decline associated with thickened membrane thickness entailed from the nAg-pDA coating. Instead, it can simultaneously accomplish a reduction in membrane biofouling and an increase in electricity generation in an OsMFC.