Electricity Generation And Perchlorate Degradation In Microbial Fuel Cells With Iron/carbon Material Electrodes

Microbial fuel cells?MFCs?was a green energy technology which used microorganism as catalyst extraction of electric energy from degradable organic matter directly,and achieved energy conversion.The unique adsorption and degradation properties of ion/carbon materials were more prominent in water pollution treatment.The ion /carbon materials were used in MFCs to obtain electric energy as well as achieve high efficiency of pollutants degradation.This paper mainly studied Fe/C material loaded to cathode and anode in MFCs,explored MFCs electricity production,power density and electrode polarization phenomenon in running cycle.Then analysed the feasibility of replacing expensive Pt/C catalytic material with Fe/C material.In order to play the advantages of ion/carbon materials in the groundwater pollution control,used MFCs to produce electricity performance,further researched on the persistence of pollutants?Perchlorate,ClO₄^-?removal in MFCs.Investigation of adsorption property,DO condition,optimal pH condition of Fe/C particles on ClO₄^-degradation in this paper.Double chamber MFCs with five kinds of cathode materials were constructed,including Fe/C nanoparticles?Fe/C?,iron sheet?IS?,Fe0 particles?Fe0?,blank carbon felt?CF?and active carbon powder?AC?.The stability of system,the residence time,external load resistance,electrode potential,the change of pH of anolyte and catholyte,and ClO₄^-concentration and its decomposition products were analyzed during the reactors operation.Finally,the specific surface area,pore size distribution and relative elements on the surface of the cathode materials were characterized by N₂ adsorption-desorption isotherm and X ray photoelectron spectroscopy?XPS?.Experiment proved that various complex electrochemical processes exist simultaneously,such as the production process of MFCs,the adsoption co-sedimentation and chemical reaction process between cathode materials and ClO₄^-,the potential between two electrodes and pH change process,etc.Without additional energy or the Perchlorate Reducing Bacteria?PCRB?enrichment culture,these reactors could achieve effective removal of ClO₄^-in cathode chambers under the condition of loading 100 ? external resistance.The highest degradation rate of Fe/C,IS,and Fe0 in the iron containing MFCs systems were 18.96,10.24 and 15.84 mg/L/day.In the non iron MFCs systems,and CF and AC systems were 14.37 and 19.78 mg/L/day.Experimental results showed that ion/carbon materials loaded in MFCs cathode could degrade ClO₄^-quickly and recovery of ClO₄^-degradation products was non-toxic Cl-.Howevre,the chlorine recovery rate was lower than the theoretical value,the chlorine recovery imbalance was mainly due to the degradation products of ClO₄^-combined with the oxide or hydroxide formed by the oxidation of the cathode iron to form complex compound,a portion of which were adsorbed and sedimentation on the surface of cathode materials or inside iron oxide films,and deposited at the bottom of the reactor.The other part was suspended in the solution,removed by 0.22 ?m membrane filtration without detection.Ion/carbon materials cathodic reduction combined with MFCs played a key role in the degradation of ClO₄^-,reduced the harm to human boby and purified ClO₄^-pollution in groundwater.Delving into iron and ClO₄^-reduction mechanism and iron material reused in the system have important significance for treatment underground pollution of ClO₄^-.