Influence of praseodymium(iii) chloride on corrosion resistance of AS1020 steel in an environment containing chloride ions and carbon dioxide

Rare earth salts (RESs) are considered one of the good choices for anticorrosion due to their high inhibition efficiency via the suppression of oxygen reduction reactions. In this work, praseodymium chloride (PrCl₃) was used as a potential inhibitor that can become a promising candidate for mitigating mild steel corrosion in environments rich in chloride and carbon dioxide. The results of electrochemical and surface analyses indicated that mild steel was protected from corrosion in a CO₂-saturated sodium chloride solution throughout 72 hours immersion when PrCl₃ was added to the solution. This was evidenced through considerably reduced corrosion current density, increased protective and charge transfer resistances, especially, random redistribution of minor anodes, as well as less corrosion-induced damages on the steel surfaces. Tafel extrapolations were applied to estimate the inhibition efficiency of PrCl₃, achieving the highest value of 96.33 ± 0.47 % at 2.4 mM PrCl₃. This positive result is primarily attributed to the formation of the barrier layer from praseodymium oxides and hydroxides in combination with iron(II)-based products. Based on these findings, this work recommends a potential inhibitor for mitigating mild steel corrosion in aqueous media containing carbon dioxide and chloride ions.