EVALUATION OF FERROUS IONS INFLUENCE ON THE MICROBIAL CORROSION OF IRON BY SCANNING ELECTRON MICROSCOPY

The aim of this investiagtion was to evaluate the effect of the presence of ferrous ions (Fe(++)) in the microbial corrosion of iron by Sulfate-Reducing Bacteria (SRB) through Scanning Electron Microscopy (SEM), watching the differences generated in the biofilms and the type of attack in cultures medium with and without these ions. The results showed that the Fe(++) ions accelerate the corrosive process and it was demonstrated that the position of the metallic surfaces, horizontal or vertical, influences the generation of different attack morphologies, being uniform for horizontal positionated surfaces and localized for vertical placed surfaces. Finally, it was determined that the most aggressive condition for iron surfaces in contact with SRB corresponds to a system with ferrous ions in vertical position, where iron sulfides are little protectives and become detached easilly acelerating the corrosion process by formation of galvanic cells.