Research In Anodes Modified By Polyaniline And Its Composites For Microbial Fuel Cells

Microbial fuel cell（MFC）is a new green energy technology integrating sewage processing and electricity generation.It degrades organic matters with microorganisms and transforms chemical energy into electricity.Due to a growing demand for environmental protection and sustainable development,MFC has attracted widespread attention,particularly for sewage processing and environmental-friendly energy applications.There are extensive sources of wastewater that can be degraded by MFC,such as domestic wastewater,kitchen wastewater,dye wastewater and other types which are difficult to degrade.At present,MFC is still in the laboratory research stage,and low output power density is the main factor to limit its practical application.As an important component of MFC,the performance of anode directly influences the output power density of MFC.Therefore,anodic modification has become the focus of MFC research.The purpose of the modification is to obtain high performance anode with large surface area,good electrical conductivity and good biocompatibility.The purpose of this study is to prepare high performance anode materials by carbon-based materials modifying using polyaniline and its composite materials.Then the anode materials prepared were equipped in MFC to investigate its performances of the electricity production and reactive brilliant red X-3B（RBR）degradation.The main contents and conclusions of the study are as follows:1.The polyaniline（PANI）-modified carbon felt film（PANI-CF）electrode was prepared by electrochemical deposition.The best preparation conditions were obtained as follows:0.2 mol·L^-1aniline,sulfuric acid as the doped acid,and electropolymerized 40 cycles.Compared with the traditional carbon felt（CF）electrode,PANI-CF electrode effectively improves its conductivity and specific surface area,which is conducive to the growth and adhesion of electrogenic bacteria.The maximum output voltage and output power density of the MFC（PANI-MFC）using the PANI-CF electrode as anode were 581.6 mV and 578.6 mW·m^-2 respectively,which were 1.37 and 3.5 times that of the carbon felt anode MFC（CF-MFC）respectively.In the treatment of RBR dyes,PANI-MFC showed a good performance.The color and COD removal efficiencies of RBR reached 91.3%and 52.9%at 48 h respectively.The biodiversity analysis showed that polyaniline effectively enhanced the biocompatibility of the electrode.The proportion of Proteobacteria bacteria in the anodic biofilm modified by PANIwas significantly higher than that of the unmodified CF electrode,which is conducive to the growth of the iconic Geobacter bacteria.2.The electrode which embedded PANI in petaline NiO（NiO@PANI-CF）was prepared through in-situ growth and in-situ polymerization.The NiO@PANI-CF integrated the high capacitive character of NiO and the high conductivity of PANI,which effectively increased electricity generation capacity of the MFC（NiO@PANI-MFC）using NiO@PANI-CF electrode as anode.The maximum output power density and output power density of NiO@PANI-MFC were1078.8 mW·m-² and 725 mV respectively,which were 6.6 times and 1.71 times that of CF-MFC respectively.The charge transfer resistance of NiO@PANI-MFC was only 10.4Ω,which was 68%lower than that of CF-MFC.Moreover,NiO@PANI-MFC could effectively biodegrade dye wastewater.The color and COD removal efficiencies of RBR reached 95.94%and 64.24%at 48h respectively.The biodiversity analysis of electrode showed that the Shannon index of NiO@PANI-CF biofilm was the highest,and the Geobacter bacteria abundance was as high as15.44%,which was conducive to the growth of Geobacter bacteria.3.A carbon@polyaniline carbon felt electrode（C@PANI-CF）with nano-porous cotton network structure was prepared by dip-coating and temperature programmed calcination.The electrode with a porous nanostructure effectively increases the specific surface area and has a good electrochemical performance.The maximum output power density and output power density of the MFC（C@PANI-MFC）using C@PANI-CF electrode as anode were 1105.1 mW·m-² and686 mV respectively,which were 6.6 times and 1.62 times that of CF-MFC respectively.The charge transfer resistance of C@PANI-MFC was only 7.1Ω,which was 78.6%lower than that of CF-MFC.The color and COD removal efficiencies of RBR reached 97.22%and 65.33%at 48 h respectively.Compared with other anode MFCs,C@PANI-MFC maintains the highest output power density,up to 740.1 mW·m-²,during the process of RBR dye wastewater degrading.In this dissertation,high-performance anode materials were prepared by modifying carbon felt with polyaniline and its composites,which effectively improved the MFC production performance and dye wastewater degradation performance.The electrode preparation method can provide a new idea for the modification of MFC anode.