TY - JOUR
T1 - Hydrogen production rates with closely-spaced felt anodes and cathodes compared to brush anodes in two-chamber microbial electrolysis cells
AU - Zikmund, Emily
AU - Kim, Kyoung Yeol
AU - Logan, Bruce E.
N1 - Funding Information:
The research was supported by funds provided by the National Renewable Energy Laboratory (NREL) through the Department of Energy (DOE) CPS Project #21263 .
Publisher Copyright:
© 2018 Hydrogen Energy Publications LLC
PY - 2018/5/17
Y1 - 2018/5/17
N2 - Flat anodes placed close to the cathode or membrane to reduce distances between electrodes in microbial electrolysis cells (MECs) could be used to develop compact reactors, in contrast to microbial fuel cells (MFCs) where electrodes cannot be too close due to oxygen crossover from the cathode to the anode that reduces performance. Graphite fiber brush anodes are often used in MECs due to their proven performance in MFCs. However, brush anodes have not been directly compared to flat anodes in MECs, which are completely anaerobic, and therefore oxygen crossover is not a factor for felt or brush anodes. MEC performance was compared using flat felt or brush anodes in two-chamber, cubic type MECs operated in fed-batch mode, using acetate in a 50 mM phosphate buffer. Despite placement of felt anodes next to the membrane, MECs with felt anodes had a lower hydrogen gas production rate of 0.32 ± 0.02 m3-H2/m3-d than brush anodes (0.38 ± 0.02 m3-H2/m3-d). The main reason for the reduced performance was substrate-limited mass transfer to the felt anodes. To reduce mass transfer limitations, the felt anode electrolyte was stirred, which increased the hydrogen gas production rate to 0.41 ± 0.04 m3-H2/m3-d. These results demonstrate brush electrodes can improve performance of bioelectrochemical reactors even under fully anaerobic conditions.
AB - Flat anodes placed close to the cathode or membrane to reduce distances between electrodes in microbial electrolysis cells (MECs) could be used to develop compact reactors, in contrast to microbial fuel cells (MFCs) where electrodes cannot be too close due to oxygen crossover from the cathode to the anode that reduces performance. Graphite fiber brush anodes are often used in MECs due to their proven performance in MFCs. However, brush anodes have not been directly compared to flat anodes in MECs, which are completely anaerobic, and therefore oxygen crossover is not a factor for felt or brush anodes. MEC performance was compared using flat felt or brush anodes in two-chamber, cubic type MECs operated in fed-batch mode, using acetate in a 50 mM phosphate buffer. Despite placement of felt anodes next to the membrane, MECs with felt anodes had a lower hydrogen gas production rate of 0.32 ± 0.02 m3-H2/m3-d than brush anodes (0.38 ± 0.02 m3-H2/m3-d). The main reason for the reduced performance was substrate-limited mass transfer to the felt anodes. To reduce mass transfer limitations, the felt anode electrolyte was stirred, which increased the hydrogen gas production rate to 0.41 ± 0.04 m3-H2/m3-d. These results demonstrate brush electrodes can improve performance of bioelectrochemical reactors even under fully anaerobic conditions.
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U2 - 10.1016/j.ijhydene.2018.04.059
DO - 10.1016/j.ijhydene.2018.04.059
M3 - Article
AN - SCOPUS:85046171912
VL - 43
SP - 9599
EP - 9606
JO - International Journal of Hydrogen Energy
JF - International Journal of Hydrogen Energy
SN - 0360-3199
IS - 20
ER -