Electrochemical Behavior of X52 Steel in a CO2 Environment in the Presence of Acetate and sulfide

The objective of this study is to evaluate the combined effect of sulfide and acetate on the corrosion behavior of X52 steel in a CO2 environment. The tests were conducted in a 0.5 M NaCl solution (25 °C). Corrosion rate and behavior were investigated using the following three electrochemical techniques: (a) linear polarization resistance, (b) potentiodynamic polarization, and (c) electrochemical impedance spectroscopy. The morphology of surface corrosion products were analyzed using field emission scanning electron microscopy/energy dispersive spectroscopy and X-ray diffraction tests. The results show that the addition of sulfide ions decreased the corrosion rate of X52 steel sample. The inhibitive effect of sulfide ions was related to protective pyrite FeS layer on the electrode surface. Furthermore, in the presence of sulfide, acetate increased the X52 steel corrosion rate by enhancing the cathodic reaction. On the contrary, in the absence of sulfide, acetate decreased the corrosion rate of the X52 steel sample when the pH solution was increased.