| Microbial fuel cell(MFC)is the device for the production of biological electrical energy by the bacteria through the biomass in the waste water.Pt,as the traditional air cathode catalyst,has high cost and poor sustainability in long-term operation.Therefore,it is of great significance to find alternative catalysts to promote the practical application of MFC.In this paper,the oxygen reduction capacity of carbon nanotubes doped with nitrogen and metal oxides as air cathode catalysts was compared,as well as the influence of different preparation methods on the electrical properties of MFC.In addition,the air cathode MFC was applied to the removal of ceftazadine(CAZ)in water,and the degradation pathway and products were explored.(1)Five kinds of cathode catalysts(N-CNT,In2O3-CNT,Al2O3-CNT,NiO-CNT and bare CNT)were prepared and compared.SEM and TEM showed that the four dopants could be uniformly attached to CNT with clear particles and tight arrangement.NiO-CNT got the highest power density which was about 541.1 mW/m2.Further comparison was made on the electrical properties of NiO doped CNT with different concentrations.The maximum power density of Ni/C(1:2)reached 57 7.4 mW/m2.The performance of NiO-CNT air cathode at Ni/C(1:2)was the best conbining oxygen reduction activity and internal resistance.(2)The effects of different cathode preparation methods on MFC electricity generation were compared.The results showed that the electrode produced by roller pressing method was superior to coating method,and the carbon black to ammonium nitratewith the mass ratio of 4:3 was superior to the electrode with the mass ratio of 2:1.When C/N was 2:1,the oxygen diffusion coefficient was larger and the activity of anode microorganism was lower,indicating that the appropriate amount of pore former can promote the oxygen reduction reaction at the cathode.However,the excessive pore former may affect the activity of anode microorganism and thus affect the electricity generation of MFC.(3)The effects of different working conditions on on the degradation of CAZ by MFC were compared.It was found that with the increase of CAZ concentration,the output electric energy of MFC gradually decreased,and the maximum degradation rate of CAZ was set at 0.2 mg/L.The effects of different COD concentrations on the performance of MFC were compared.When the inlet COD concentration was 1000 mg/L,MFC had the strongest ability to degrade pollutants.For the addition of Tween 80,the output power of MFC is positively correlated with the concentration,and the maximum power density can be up to 566.8 mW/m2.After the addition of ceftaxidine,the dominant bacteria evolved from the spherical bacteria to the rod-shaped bacteria in the anode microorganisms.(4)Under optimal conditions,the removal rate of CAZ by MFC was 89%,and that of ABS was about 46%.Both biosorption and biodegradation existed in the two systems in the first two hours,and both of them met the first-order reaction kinetic model within 2 h-12 h.CAZ can be degraded under the action of electroproducing bacteria of MFC anode and suspended microorganisms in the system.In the degradation process,C-N bond breaks first,followed by C-C=N bond. |
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