Dissertation > Excellent graduate degree dissertation topics show

Research of Anode Surface Modification and Electrode Shape in the Benthic Sediment Microbial Fuel Cell

Author: LiJianHai
Tutor: FuYuBin
School: Ocean University of China
Course: Materials Physics and Chemistry
Keywords: Microbial fuel cell Graphite anode Chemical oxidation modified Wettability Electrode configuration
CLC: TM911.4
Type: Master's thesis
Year: 2010
Downloads: 189
Quote: 3
Read: Download Dissertation

Abstract

One of the main challenges we face in the 21st century is the energy shortage and environmental pollution. Renewable biomass does not increase net emissions of carbon dioxide are being recognized as one of the ways to slow down the current energy and environmental crisis. The microbial fuel cell (MFC) is a catalytic action of microorganisms can use the means of generating electrical energy by oxidation of organic and inorganic substances. It is a new technology, the use of wastewater or other waste to generate electricity has great research value and development space. The the seafloor sediment microbial fuel cell (BMFC) is a special form of MFC, in the submarine environment. The BMFC anode buried in the marine sediments of the anaerobic organic matter in marine sediments as the \BMFC has a maintenance-free, continuous supply of substrate, low internal resistance, environment-friendly and low cost, so it is very promising as an energy device used to drive low-power monitoring equipment in remote waters. However, the current limit BMFC widely key problem is the relatively low output power density. To BMFC increase the output power density, built in the laboratory on the basis of seafloor sediment microbial fuel cells, we studied the graphite anode surface modification of chemical oxidation and electrode configuration on the battery performance. The main block diagram of the research program see appendix, and the results are as follows: (1) by type of chemical oxidation of the graphite electrode, a modification treatment, and were characterized by SEM, EDX and adsorption experiments variation in characteristics of the surface of the electrode before and after the modification. The results showed that: the graphite electrode after chemical oxidation reforming a significant increase in specific surface area and surface wettability. Acidic KMnO4, concentrated HN03 and mixed acid (concentrated H2SO4 and concentrated HN03) modified graphite electrode real surface area increased by 49%, 56% and 67%, respectively; surface contact angle decreases from 132 ° to 63 °, 58 ° and 42 °. Electrochemical and other experiments showed that: chemical oxidation of graphite electrodes modified have a positive impact on the battery performance to improve, you can increase the dynamic activity of the electrode. After acidic KMnO4, concentrated HN03 and mixed acid (concentrated H2SO4 and concentrated HN03) the modified corresponding BMFC maximum output power density increased from 24.6 mW/m2 40.6m W/m2, 44.4 mW/m2 and 44.5 mW/m2; apparent internal resistance of the battery corresponding decreases from 732Ω to 443Ω, 462Ω, and 482Ω; exchange current density from the 1.965 × 10-3A/m2 to 0.309A/m2, 2.586 A/m2 and 0.893 A/m2. By coating the anode the results of the analysis of the number of microorganisms: the of four graphite electrode surface microbial bacterial density were of 5509/cm2, 16526/cm2, 51988/cm2 and 17559/cm2. This result and the electrode surface fluorescence microscopy analysis results. Long-term discharge experiments: modified graphite anode in the battery during start-up showed strong anti-polarization, the modified graphite electrodes as the anode BMFCs in the long-term power output higher voltage. Modified by chemical oxidation, the graphite electrode surface wettability increase than the increase in surface area, the surface chemical reaction active sites increased, the biocompatible increase (increased biocompatibility is by the process of modification in graphite caused by the oxygen-containing functional groups introduced on the surface of the electrode) is a the BMFC performance the main. In this study, the first study of the relationship between the the the BMFC anode surface wettability and its electrochemical properties. The materials and equipment used in the chemical oxidation process are common and inexpensive, and the method is easy to achieve industrialization. Therefore, the chemical oxidation of the modified graphite electrode is a BMFC performance ideal method. (2) because the structure of the electrode has a great influence on the seabed sediment microbial fuel cell performance (BMFC)'s, the experimental design of the graphite electrodes of different shapes (cylindrical, disc-shaped, barrel-shaped). Cylindrical and disc-shaped electrode of BMFC highest output power density 20.2 mW/m2 and 14.9mW/m2, battery internal resistance of 333Ω and 598Ω. The inner diameter were 2.5 cm, 1.0 cm, 0 cm graphite barrel electrode composed of three BMFC referred to as BMFC-Ⅰ, BMFC-Ⅱ and of BMFC - Ⅲ. The results show that of BMFC - I BMFC-II, and of BMFC - Ⅲ maximum output power density of 13 mW/m2 and 11 mW/m2 and 16 mW/m2, the battery internal resistance of 435Ω, 488Ω, and 419Ω. BMFC-a (made by the porous electrode assembly) and BMFC-b (formed by the flat electrode assembly) maximum output power of 37.6 mW/m2 and 28.3 mW/m2, the internal resistance of 203Ω and 265Ω. BMFC-A (Tablet cathode) and the BMFC - B (three-phase cathode) maximum output power of 16.7 mW/m2 and 25.6 mW/m2, the internal resistance of 357Ω and 268Ω. Description the columnar porous electrode structure and disc-shaped and barrel-shaped electrode structure compared with the smaller internal resistance and higher power density. The cathode of the three-phase interface can be improved BMFC power output density. The findings can design for the the BMFC electrode structure in practical application to provide a reference. In short, by chemical oxidation of graphite anode modification and optimization of the electrode configuration in practical applications to further improve the BMFC performance.

Related Dissertations

CLC: > Industrial Technology > Electrotechnical > Independent power supply technology (direct power) > Chemical power sources,batteries, fuel cells > Fuel cell
© 2012 www.DissertationTopic.Net Mobile