Corrosion inhibition by the trace amount of sulphide ion in CO₂-saturated brine solutions

Abstract

By accurately controlling the concentration of sulphide ion in CO₂-saturated solutions, it was demonstrated that the corrosion behaviour of mild steel was sensitive to the trace amount of sulphide ion additions. An obvious inhibition effect on cathodic reactions was observed at an extremely low level of sulphide ion, while a detrimental effect on corrosion was gradually emerged as its dosage increased higher than 0.5 mg L⁻¹. These positive and negative synergy effects would be strengthened after immersing for longer time. The sensitivity of CO₂ corrosion to sulphide ion was attributed to the modification of surface properties by the presence of iron sulphides.

Keywords:

• CO₂ corrosion
• Pipeline steel
• Sulphide ion
• Corrosion inhibition

Acknowledgements

This work was supported by the National Key Technology R&D Program (No. 2012BAC24A04) and the Sinopec Tahe Oilfield Company.