Study of the cathodic despolarization theory with hydrogen permeation and the bacteria Desulfovibrio desulfuricans

Abstract

A Desulfovibrio desulfuricans ssp. desulfuricans (SRB) was used to study the permeation of hydrogen, using a Devanaran and Stachurski cell and a palladium sheet. The aim was to evaluate cathodic depolarization as a Sulfate-Reducing Bacteria action mechanism in Microbiologically Induced Corrosion. The permeation tests were run with and without cathodic polarization, using a sterile deaerated culture medium inoculated with 10 % SRB concentrated at 10⁸ cel/ml. The results indicate bacterial growth in the order of 10⁹-10¹⁰ cel/ml after 18 h both in the polarized and non-polarized tests, indicating that SRB developed regardless of the surface polarized as a source of H⁰, generating H₂S as a product of the anaerobic respiration. It was also determined that, without cathodic polarization, the conditions are not enough to reduce the H⁺ generated by the H₂S dissociation (Pd is not susceptible to corrosion at this condition). On the other hand, cathodic polarization increased the permeation current, which was associated with the maximum enzymatic activity phase of the bacteria.