KINETIC-STUDIES ON THE SRB INFLUENCED CORROSION OF STEEL - A FIRST APPROACH

The influence of the sulphate reducing bacteria (SRB) Desulfovibrio de sulfuricans ATCC27774, grown in a lactate/sulphate medium, on the anae robic corrosion of mild steel was evaluated. Potentiodynamic polarisat ions (both unidirectional and cyclic) were performed, both in the inoc ulated and in the sterile media. Cyclic voltammograms as well as quasi -steady-state polarisation curves showed significant differences when in the presence of a 1 day old bacterial culture. Higher corrosion rat es as well as the transpassive dissolution of Fe(0) or Fe(II) compound s to Fe(III) were observed. These effects are most probably due to hig h quantities of sulphide and/ or to other alterations in the sulphate/ lactate medium produced by the microbial activity of the SRB. Tafel an alysis of the polarisation curves around the corrosion potential, E(co rr), allowed us to confirm that the presence of SRB induces changes in the kinetics and also in the mechanism of the anodic dissolution of i ron in the lactate/sulphate media. (C) 1997 Elsevier Science Ltd.