Abstract
Biochar is a kind of carbon-rich material formed by pyrolysis of biomass at high temperature in the absence or limitation of oxygen. It has abundant pore structure and a large surface area, which could be considered the beneficial characteristics for electrodes of microbial electrochemical systems. In this study, reed was used as the raw material of biochar and six biochar-based electrode materials were obtained by three methods, including one-step biochar cathodes (BC 800 and BC 700), biochar/polyethylene composite cathodes (BP 5:5 and BP 6:4), and biochar/polyaniline/hot-melt adhesive composite cathode (BPP 5:1:4 and BPP 4:1:5). The basic physical properties and electrochemical properties of the self-made biochar electrode materials were characterized. Selected biochar-based electrode materials were used as the cathode of sediment microbial electrochemical reactors. The reactor with pure biochar electrode (BC 800) achieves a maximum output power density of 9.15 ± 0.02 mW/m2, which increases the output power by nearly 80% compared with carbon felt. When using a biochar/polyaniline/hot-melt adhesive (BPP 5:1:4) composite cathode, the output power was increased by 2.33 times. Under the premise of ensuring the molding of the material, the higher the content of biochar, the better the electrochemical performance of the electrodes. The treatment of reed powder before pyrolysis is an important factor for the molding of biochar. The one-step molding biochar cathode had satisfactory performance in sediment microbial electrochemical systems. By exploring the biochar-based electrode, waste biomass could be reused, which is beneficial for the environment.
Highlights
Microbial electrochemical systems (MESs) have drawn increasing attention as a method that can simultaneously produce electricity and treat wastewater
The weight loss of hemicellulose and cellulose during pyrolysis mainly happened below 400 degrees, while lignin was more difficult to decompose and its weight loss happened from 160 to 900 degrees and generated solid residue [29]
The results showed that BC 800 and BC 700 can improve the electricity generation performance of sediment microbial electrochemical systems compared with the carbon felt cathode, and these two materials have similar ability to improve the electricity generation (30 mV)
Summary
Microbial electrochemical systems (MESs) have drawn increasing attention as a method that can simultaneously produce electricity and treat wastewater. Cathode materials have a direct impact on the performance of MESs. Cathode materials have a direct impact on the performance of MESs They should have high oxidationreduction potential to capture electrons. It is important to study the cathode materials of MESs. At present, common cathode materials include graphite, carbon cloth, and carbon paper. In order to improve the performance of the materials, high active catalysts can be used to modify the cathode to reduce the activation energy and improve the reaction rate
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