Study On The Application In Wastewater Treatment From Microbial Fuel Cell Of Using Metal-doped Carbon Nanotubes Modified Electrodes

Microbial fuel cell (MFC) is a new type of water treatment technology which can produce electricity and purify sewage, so it is the major innovation of the sewage treatment of the concept. MFC has many advantages such as wide variety of sources, mild reaction conditions, environment-friendly, substrate chemical energy can be transformed into electrical energy directly, environmental pollution, and so on. However, the low of production performance limits the promotion and application of MFC.Reactive mode (single or two-chamber MFC, rotating cathode type and so on), microorganism, substrate concentration, the electrodes are the main factors to affect the production performance of MFC. Anodes are the place, where are atached by the micobial and the ability to produce electronic. Anode materials and structures have a direct impact on substrate oxidation, electronic production and the electronic transfer and other processes, so choosing appropriate anode materials and structures are the key factors to improve the production performance of MFC. In this study mainly studyed the anode material of MFC, and choosed the best metal elements-doped carbon nanotubes modified electrodes.In this paper, we studyed the metal elements-doped carbon nanotube modified electrodes were used as anode to affect the production performance of MFC and investigated the factors of the preparation conditions of electrodes, the choice of the types of metal elements, doping content, the temperature of the reaction chamber, the initial concentration of substrate and the removal rate of COD. The major substrate are99.9%pure titaniums, secleted Zn, Cd, Ag, La, Gd five metal elements that combined with the pretreatment of carbon nanotubes respectively, prepared different metal elements-doped carbon nanotube modified electrodes by the solution blending method. A two-chamber microbial fuel cell was constructed by using metal elements-doped carbon nanotubes modified electrodes as anode, flexible graphit as cathode, saturated calomel electrode as the reference electrode and glucose as the matrix configuration simulation wastewater. Taking the simulation wastewater as target degradants to examine the production performance of different anode materials in MFC. The electrode materials were characterized by IR. SEM, EDX and XRD to study the structure of carbon nanotubes titanium plate, the crystal form of doping metal elements into carbon nanotubes-titanium plate and the doping methods of metal elements. The results showed that surface-modified carbon nanotubes(CNTs) were added into the titanium plate or flexible graphite to accelerate the formation of electricity generation biofilm anf improve the electricity generation capacity of the whole biofilm; the preparation of metal elements-doped carbon nanotubes modified electrodes had better production performance:carbon nanotubes composite material synthesized after metal elements catalysts were added had higher specific surface area and interface, could combine proton produced by electricigenic microorganism more easily, which could increase the ability of electron transfer and thus enhance electricigenic power density and current density further. The Zn-doped carbon nanotubes modified electrodes had more effective than Cd belongs to the same pair of family, which is also better than Ag and rare earth elecments under the same conditions; in the conditions of external resistance of2300Ω, the temperature of the reaction chamber was40℃, the concentration of waste water was1257mg·L-1, ZnS doped0.5g, it had the optimal performance, which the average output voltage was859mV, the maximum output voltage was1030mV, the maximum power density was31.2mW·m-2, the maximum current density was94.67mA·m-2, and the COD removal efficiency was about92%.The innovations of this work included:(1) the optimum preparation conditions and the optimum catalytic condituons of the preparation of metal elements-doped carbon nanotubes modified electrodes;(2) selected metal elements-doped carbon nanotube modified electrodes with the best production performance and studyed it, discussed the mechanism of the influence induced by doping on metal elements for the production performance, and the effect of wastewater treatment of MFC.