Application Of Modified Anode In Treatment Of Cr Wastewater By MFC

Microbial fuel cell(MFC)is an emerging water treatment technology that can use organic matter as its own fuel,under the action of microorganisms,the organic matter could be oxidized and resolved,at the same time outputing energy,which has the outstanding features of processing waste water and generate electricity.Hexavalent chromium can be used as the cathode electron acceptor,realizing the treatment for waste water with chromium.At present,the production capacity of MFC is low,the main limiting factor is the larger internal resistance.How to reduce the MFC internal resistance has the great significance of improving the MFC production performance.In this study,carbon microspheres modified electrode and carbon nanotubes mixing up with iron oxide modified electrode were prepared.while graphite sheet were used as control,the modified electrode was characterized.The modified electrode was applied to MFC anode,investigating the effects of modified electrode on the electricity generation performance.The modified electrode was applied to the treatment of chromium-containing wastewater,then the electrolysis of MFC and the removal rate of chromium were investigated.The experimental results are as follows:(1)After the electrode was modified,the surface became rough.EDS test showed that Fe3O4 was successfully attached to the electrode,and the contact angle of the electrode was increased.The BET test showed that specific surface area of carbon microspheres modified electrode was 4.120 m2/g,carbon nanotubes mixing up with iron oxide modified electrode was 3.984 m2/g,higher than unmodified electrode(3.614 m2/g).The cyclic voltammetry curve showed the electron transfer rate of modified electrode was accelerated.EIS test showed that the resistance of modified electrode became smaller,in which the carbon microsphere modified electrode had the smallest ohmic resistance.(2)Modified electrode being anodes were used in MFC,graphite anode of MFC had the maximum output voltage,which was 0.62 V.The maximum output voltage of MFC with carbon microsphere modified electrode and carbon nanotubes loading iron oxide modified electrode were respectively 0.79 V and 0.75 V,Which is higher than that of the MFC with unmodified electrode,approximately 0.17 V,0.13 V.The internal resistance of the electrode decreased while the power density improved by nearly 3 times.The COD removal rate of MFC was 58.8%,68.2% and 69.9% respectively,and the Coulomb efficiency was 7% 16.6%,21%.(3)The MFC with modified electrode was used for treating chromium-containing wastewater,Output voltage of MFC with the carbon nanotubes loading with iron oxide modified electrode were the highest,which was 0.30 V,while MFC with carbon microsphere modified electrode was 0.28 V,MFC with graphite sheet anode was 0.11 V,increasing approximately 1.73 times,1.55 times,respectively.The output power density of the three MFC were 56mW/m2,30mW/m2,28mW/m2,while the removal rate of Cr6+ were 83%,76%,38%,increased 1.18 times,1time respectively.The concentration of total chromium in the catholyte decreased,and the XPS test results showed that the precipitates was Chrome trioxide.