Study On The Electricity Generation And Sulfonamide Antibiotic Removal Performance Of Polythiophene Composite Hydrogel Materials In Microbial Fuel Cells

Microbial Fuel Cell（MFC）combines the characteristics of electricity generation and organic wastewater degradation,and is currently a hot research topic in the field of new energy and the environment.Among them,the choice of anode material is very important to the electricity generation performance of MFC.This paper mainly chooses the representative poly（3,4-ethylenedioxythiophene）:polystyrene sulfonate（PEDOT:PSS）among polythiophene conductive polymers.The composite hydrogel electrode is used as the MFC anode to improve the electricity generation performance of the MFC,and it is applied to the treatment and energy recovery of simulated sulfonamide antibiotic wastewater.PEDOT:PSS-X hydrogel（X is the molar mass ratio of monomer EDOT to PSS during material preparation,X=0.5,1,1.5,2）was grown in situ on the carbon felt by chemical oxidation method.SEM test showed that the prepared electrode showed a loose and porous structure surrounded by many nano microspheres,which could make microorganisms adhere to the electrode.PEDOT:PSS-1.5 was selected as the best electrode by electrochemical testing method.When the prepared electrodes were used as MFC anodes,the MFC with PEDOT:PSS-1.5 as anode also showed the best power generation performance,and the maximum power density could reach 8.45 W/m³,which was 1.53,1.13 and 1.49 times higher than that of PEDOT:PSS-0.5,PEDOT:PSS-1 and PEDOT:PSS-2 anodes MFC.This is because the PEDOT backbone is positively charged,which can produce electrostatic interaction with negatively charged microorganisms,so as to promote the formation of biofilm.And under the optimal ratio,the synergy of PEDOT and PSS reached the best,making the prepared PEDOT:PSS-1.5electrode the best electrochemical performance,and the charge transfer resistance(R_ct)of the PEDOT:PSS-1.5 anode was only 0.97Ω.PEDOT:PSS is limited by the molecular structure of the conjugated chain,resulting in low mechanical strength of the hydrogel made by it.In this paper,PVA is introduced to solve this problem.Also,PEDOT:PSS/PVA-X hydrogel（X is the amount of PVA added during material preparation,X=2,3,4,5 m L）was grown in situ on the carbon felt by chemical oxidation method.SEM test showed that the prepared electrode presents a three-dimensional network structure connected with each other,and the pore wall was wrinkled and rough,which could attract a large number of microorganisms to attach and grow.PEDOT:PSS/PVA-4 was selected as the optimal electrode by electrochemical test method.PEDOT:PSS/PVA-4 electrode had a larger area specific capacitance and bioelectrocatalytic activity.When the prepared electrodes were used as MFC anodes,the maximum power density of MFC with PEDOT:PSS/PVA-4 as anode was 9.34 W/m³,which is 1.20 times higher than that of PEDOT:PSS/PVA-2 anode;The maximum current density was 7.5 A/m²,which was 1.23 times higher than that of PEDOT:PSS/PVA-2 anode.And the R_ct of PEDOT:PSS/PVA-4 anode was only 0.71Ω.High-throughput sequencing was performed on the inoculated raw sea mud,PEDOT:PSS-1.5 anode and PEDOT:PSS/PVA-4 anode.The results showed that the microbial community in the original sea mud changed with the operation of MFC.A variety of electricity producing bacteria and functional bacteria were enriched on the surfaces of PEDOT:PSS-1.5 anode and PEDOT:PSS/PVA-4 anode,mainly Geobacter and Azospirillum,They can degrade refractory compounds and participate in the key EET process in bioelectrochemical system.Moreover,67.5%of PEDOT:PSS/PVA-4 anode produce electricity,while 62.4%of PEDOT:PSS-1.5anode.The protein content test showed that there were more microorganisms attached to PEDOT:PSS/PVA-4 anode,so the number of electricity producing bacteria WAS significantly higher than that of PEDOT:PSS-1.5 anode.Using 1000 mg/L sodium acetate and different concentrations of SMM to simulate sulfonamide antibiotic wastewater,it has been proved that MFC could simultaneously degrade sulfonamide antibiotics and generate electricity.When sodium acetate,an organic substance that was easy to be utilized by microorganisms,existed,with the increase of SMM concentration,the maximum power density of MFC decreased from 7.24 W/m³ to 5.60 W/m³,and R_ct also increased from 0.98Ωto 1.91Ω.This was due to the toxic effect of SMM,the number of dead cells increased,increased the distance between the electrode and the active biofilm,and hinders the EET process.A control test was designed to eliminate the adsorption of electrode materials on SMM,which proved that the degradation of SMM by MFC was mainly microbial degradation,and the removal rate of SMM by MFC for different concentrations could reach 60%.Experiments showed that only SMM in the substrate can not degrade microorganisms and produce electrons.Changing the type of sulfonamide antibiotics to SMX,MFC can still produce electricity and degrade,the maximum power density was 6.31W/m³,and the removal rate was 64%,which proved the universal applicability of MFC to sulfonamide antibiotic wastewater.At the same time,the possible paths of biodegradation of SMM and SMX were proposed.