Abstract:
During the anaerobic corrosion of steel, hydrogen sulphide
(H2S) evolution by the Sulphate-Reducing Bacteria (SRB)
promotes hydrogen absorption by enhancing cathodic hydrogen
evolution and inhibiting the combination of hydrogen atoms.
While the effects of hydrogen damage are well known, it is
unclear whether surface SRB films influence hydrogen
absorption any differently to the separate effects of H2S.
Also, for particularly hydrogen sensitive metals in soured
environments, there is some doubt regarding what constitutes
a safe but effective level of cathodic protection.
Using the electrochemical technique of Devanathan and
Stachurski, special apparatus were used to monitor hydrogen
permeation through steel foils exposed simultaneously to
cells and cell-free dialysates in batch cultures of either
Desulfovibrio vulgaris (Woolwich) or Desulfovibrio
desulfuricans (Norway 4). Further experiments were performed
using applied potentials of -850mV (SCE) and -lOOOmV (SCE),
and polarisation scans were performed on replicate steel
specimens under the same conditions. Changes in pH, Eh, cell
numbers and H2S levels were monitored during SRB growth.
