Effect of pH regulation by microbes on corrosion behaviour of duplex stainless steel 2205 in acidic artificial seawater environment

Sulphate reducing bacteria (SRB) can regulate environmental pH because of their metabolism. Since local acidification results in pitting corrosion, the potential capacity of pH regulation by SRB would have important consequences for electrochemical aspects of the bio-corrosion process. This study focussed on identifying the effect of pH on the corrosion of duplex stainless steel (DSS) 2205 in a nutrient rich artificial seawater medium containing SRB species, Desulfovibrio vulgaris. DSS samples were exposed to the medium for 13 days at 37 0C at pH ranging from 4.0 to 7.4. The open circuit potential value (OCP), sulphide level, pH and number of bacteria in the medium were recorded daily. Electrochemical impedance spectroscopy (EIS) and potential dynamic polarization were used to study the properties of the films and corrosion behaviour of the material. Inductively coupled plasma mass spectrometry (ICPMS) was used to measure the concentration of cations Cr, Fe, Ni, Mo, Mn in the experiment...