| Marine benthic microbial fuel cell (BMFC) is a new power source, it has someadvantages such as rich in substrate, maintenance free, clean and pollution-free, so itis very promising to be used as energy installations to supply continuous and reliablepower source. However, the BMFC’s commercial application is limited due to the lowoutput voltage and power density. In this paper, we used urea and mixed-acidmodified anode, decreasing anode potential, increasing BMFC performances,meanwhile investigating the influence of temperature factor for BMFC furthercommerical application. Main results are as follows:1）A novel carbon foam-plate composite anode was prepared, using urea andgraphite powder melting mixture modified composite anode. Their electrochemicalproperties of plain carbon foam (PC) and urea modified carbon foam (UC) werecompared verse plain graphite (PG) in this paper. XRD analysis showed that thecomponents of melt urea mixture were not change, nitrogen content maintained at46%. Electrochemical test results showed that PC had a lower slope of the anodepolarization, and its power density was151.3mW/m2, increasing7.7-fold. UC hadbetter wettability and anti-polarization ability than PC and PG. It is demonstrated forthe first time that the modified anode potential reduced nearly100mV, reaching-570mV (plain-440mV) and kinetic activity increased7.6-fold versus PC,553.0-foldversus PG. Its maximum power density reached256.0mW/m2, corresponding currentdensity of550.5mA/m2. Finally, the paper primarily analyzed that why the UC hasbetter performance after urea modification and long-term stability performance.2）Chemical oxidation modified anode is one important way to increase theperformance of marine benthic microbial fuel cell. Using mixed-acid modified anode，and its electrochemical performance were investigated in this paper. The resultsshowed that the hydroxyl and carboxyl groups were introduced on foam graphitesurface after modification, common graphite changed into oxidation graphite. The contact angle of modified anode decreased24.5°, resulting in higher wettability andbetter attachment for bacteria. Its exchange current density reached6760.8mA/m2and the kinetic activity was improved53.7-fold higher than the plain. Additionally,the present study also found that the anode potential of modified decreased100mV,and its open circuit potential reached865mV (plain anode750mV). The powerdensity of modified cell reached358.1mW/m~2,2.4-fold higher than that of plain foam.Cyclic voltammetry and impedance curves showed that the capacitance of modifiedanode surface was increased, showing ideal capacitance characteristic, it hasadvantage for limiting rapidly anode polarization. Three months discharge showedthat the modified anode and its cell have relatively stable performance. Meanwhile,sediment ash content was researched near modified and plain anodes, calculatingdifferent anode ability of consumption organic matter.3）The environment temperature is an important factor on marine microbial fuelcell. The results show that startup time of anode under4℃is significantly slower thanroom temperature, while cathode startup is almost no effect. Under the condition ofroom temperature the cell internal resistance is703Ω and4℃1005Ω, decreasing302Ω, meanwhile the maximum output power density increases10mW/m~2versus4℃, and the current density also increases46.6mA/m~2. The BMFC performance atlow temperature is lower than room temperature due to low microbial activity. Theexperiment provides guidance for marine benthic microbial fuel cell design in fieldenvironment and has practical significance. |
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