Abstract
In this study, 3D printing technique was utilized to fabricate three-dimensional porous electrodes for microbial fuel cells with UV curable resin, followed by copper electroless plating. A maximum voltage of 62.9 ± 2.5 mV and a power density of 6.45 ± 0.5 mWm-2 were achieved for MFCs with 3D printed porous copper (3D-PPC) anode, which were 8.3 and 12.3-fold higher than copper mesh electrode, respectively. This illustrated the great advantage of 3D porous anodes in MFCs compared to flat anode structures. Besides, the biocompatibility of the copper anode with Shewanella oneidensis MR-1 was examined by comparing with carbon cloth, which produced a 3-fold larger maximum voltage and a ~10-fold higher power density vs. 3D-PPC anode and thus indicated the possible copper corrosion during MFC operation. ICP-MS analysis of MFC solution revealed the high concentration of 732µg/L copper ions detected in the MFC effluent. This result, coupled with EDX showing the lower copper content on the 3D-PPC anode surface after >15 days of MFC operation, confirmed the copper dissolving behavior in MFC. MR-1 biofilm formation under copper suppression was finally characterized by SEM and less biofilm was observed on copper anodes, illustrating their poor biocompatibility, even though 3D printing technology and porous structures were quite promising for future scale-up.
Highlights
Microbial fuel cells (MFCs) are promising devices in wastewater treatment industry, which generate bioelectricity through degradation of organic matters with the catalysis of exoelectrogenic microorganisms (Logan, 2009; Logan and Rabaey, 2012)
Based on the equation of ρ = Rs × t, the bulk resistivity ρ of the as-deposited copper layer is calculated to be 3.88 × 10−8 Ω m, which was 2.25 times higher compared to the normal bulk copper and much better compared to the carbon cloth anode (Oh et al, 2006)
When we look at the bacterial adhesion on copper anodes, no thick biofilm was found on electrode surface like carbon cloth and copper-based MFC anodes reported by Baudler et al (2015, 2017)
Summary
Microbial fuel cells (MFCs) are promising devices in wastewater treatment industry, which generate bioelectricity through degradation of organic matters with the catalysis of exoelectrogenic microorganisms (Logan, 2009; Logan and Rabaey, 2012). Bacteria on the anode oxidize organic compounds anaerobically and produce electrons, protons and CO2. Anode, serving as the bacteria carrier in MFC, plays a significant role in bacterial adhesion and electron transfer from microbes to electrodes. 3D porous electrodes recently reported had either large (>500 μm) (Xie et al, 2011; Yong et al, 2012) or small (
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