Octylsilanol and Ce(III) ions – alternative corrosion inhibitors for carbon steel in chloride neutral solutions

Abstract

This work evaluated a corrosion inhibitor that consists of a mixture of a long chain silanol and cerium(III) salt, to protect carbon steel in 0.1 mol L–1 NaCl solution. The inhibitor solution was obtained after hydrolysis of the silane in the presence of the cerium salt. The silane concentration was kept constant at 400 ppm, while the cerium ions variated in 25, 50, and 100 ppm. The electrochemical measurements showed inhibition efficiency (% I.E.) above 96% for carbon steel in NaCl 0.1 mol L–1, in the best condition of the mixture of silanol and Ce (III) ions. The Raman spectroscopy confirmed the presence of inhibitors in the carbon steel surface even out of the solution containing the inhibitors as a persistent adsorbed film. Contact angle measurements showed the surface hydrophobicity imparted by the adsorbed corrosion inhibitor layer. SVET measurements confirmed that the corrosion inhibitors mixture can block both anodic and cathodic reactions. The studied inhibitors showed to be more efficient and/or cheaper than traditional corrosion inhibitors for neutral media.

Keywords

• Carbon steel
• Cerium salt
• Chloride solution
• EIS
• Octylsilanol
• SVET