Carbon starvation considerably accelerated nickel corrosion by Desulfovibrio vulgaris.

ABSTRACT

Carbon starvation can affect the activity of microbes, thereby affecting the metabolism and the extracellular electron transfer (EET) process of biofilm. In the present work, the microbiologically influenced corrosion (MIC) behavior of nickel (Ni) was investigated under organic carbon starvation by Desulfovibrio vulgaris. Starved D. vulgaris biofilm was more aggressive. Extreme carbon starvation (0% CS level) reduced weight loss due to the severe weakening of biofilm. The corrosion rate of Ni (based on weight loss) was sequenced as 10% CS level > 50% CS level > 100 CS level > 0% CS level. Moderate carbon starvation (10% CS level) caused the deepest pit of Ni in all the carbon starvation treatments, with a maximal pit depth of 18.8 µm and a weight loss of 2.8 mg·cm-2 (0.164 mm·y-1). The corrosion current density (icorr) of Ni for the 10% CS level was as high as 1.62 × 10-5 A·cm-2, which was approximately 2.9-fold greater than the full-strength medium (5.45 × 10-6 A·cm-2). The electrochemical data corresponded to the corrosion trend revealed by weight loss. The various experimental data rather convincingly pointed to the Ni MIC of D. vulgaris following the EET-MIC mechanism despite a theoretically low Ecell value (+33 mV).