Long-term effects of anti-biofouling proton exchange membrane using silver nanoparticles and polydopamine on the performance of microbial electrolysis cells

Proton exchange membrane (PEM) fouling in microbial electrolysis cells (MECs) is a major drawback since it limits proton migration. To mitigate membrane fouling, the typical strategy was surface coating with silver nanoparticles (AgNP) as sterilizing agents, but adverse silver release and interference on proton transfer are intrinsic constraint. In this study, to ameliorate these disadvantages the PEM was coated with AgNP and polydopamin (PDA), individually and in combination or even in different coating order, to study synergetic effects of these modifications. Combined use of PDA and AgNP showed a significantly higher MEC performance than a single coating (H2 recovery after 6 month operation; PDA_Ag = 68.12%, PDA-only = 16.1%, Ag-only = 5.69% and pristine = 3.21%). In terms of coating order, when AgNPs were coated immediately after the PDA coating, AgNPs were more uniformly formed and less released, and proton transportability (t¯+ = 0.96) was not sacrificed, showing a biofouling reduction of 80.74% compared to pristine PEM. [Display omitted] •Membrane surface modification method for anti-biofouling was developed.•Synergistic effect of silver nanoparticles (AgNP) and polydopamine (PDA) was observed.•Co-used PDA and AgNP showed an anti-biofouling effect without sacrificing H+ transfer.•This synergy improved MEC performance by 67% than control over 6-month operation.•AgNP persists on the membrane surface for long time when PDA was coated first.