2006 Ohio Student Research Forum

Abstract

Titanium Electrodes for Bacteria Fuel Cells
Leroy Long III
Wright State University
Department of Mechanical Engineering
Mentor: Dr. Daniel Young and Dr. Raghavan Srinivasan

Bacterial or microbial fuel cells (MFC) work on the principle that during metabolism certain bacteria produce electrons that can be harnessed as a source of electrical energy. The purpose of this project is to create porous titanium electrodes for use in MFC. Titanium was chosen for this experiment due to its biocompatibility and ability to bond with place holders. These porous titanium electrodes are produced through powder metallurgy (PM) techniques using -325 mesh (<45 µm) commercially pure titanium powder and two different place holders, NaCl and Cu. Place holders are powders that will initially bond with the titanium and then can be dissolved out at a later time. After the place holders are dissolved, they leave small holes in the titanium for the electrolytes to flow through.

Samples with various weight ratios of titanium to place holder material are cold compacted at a pressure of 20,000 lb. for one hour in order to produce green bodies. The samples must also undergo the process of etching through the use of water for -100 mesh (75-106 µm) NaCl powder and nitric acid for -100 mesh (75-106 µm) and -325 mesh (<45 µm) Cu powder. The samples containing Cu are left in a relatively weak state after the Cu powder is removed during the etching process. In this state, the samples can not withstand much force from human or instrumental contact. Therefore, the samples must be sintered, a process of bonding powder particles. The samples containing Cu must be dissolved before they can be sintered, while the samples containing NaCl can be sintered before being dissolved. After a sample has been both sintered and dissolved giving it a higher strength, the desired porous titanium electrode is attained and the sample can be studied. Characteristics such as surface area, microstructure, permeability, density, etc. can be determined to estimate the overall performance of the electrode as well as the energy production of the MFC.