Corrosion Inhibition in CO₂-Saturated Brine by Nd³⁺ Ions

Area of Science:

• Materials Science
• Electrochemistry
• Corrosion Engineering

Background:

• Dissolved carbon dioxide (CO₂) poses a significant corrosion threat to industrial infrastructure, particularly steel.
• Effective corrosion inhibitors are crucial for mitigating material degradation in CO₂-rich environments.

Purpose of the Study:

• To evaluate the efficacy of neodymium (Nd³⁺) ions as an inorganic corrosion inhibitor for X52 steel.
• To investigate the mechanism of corrosion inhibition in CO₂-saturated brine at varying temperatures.

Main Methods:

• Electrochemical techniques including polarization curves, open circuit potential (OCP), polarization resistance (Rp), and electrochemical impedance spectroscopy (EIS).
• Surface characterization of the protective layer formed on the steel.
• Testing in CO₂-saturated brine at 20 °C and 60 °C.

Main Results:

• Nd³⁺ ions significantly reduced corrosion rates by over 97% at 0.001 M, irrespective of temperature.
• Electrochemical data indicated increased corrosion potential and polarization resistance with Nd³⁺ addition.
• EIS confirmed the formation of a protective layer, enhancing charge transfer resistance and capacitive properties.

Conclusions:

• Neodymium (Nd³⁺) ions are highly effective inorganic corrosion inhibitors for X52 steel in CO₂ environments.
• The protective layer, identified as Nd carbonates, forms via a CO₂ capture process, enhancing steel's corrosion resistance.
• This study highlights a novel approach for mitigating CO₂ corrosion using rare-earth elements.