Synergistic improvement of inhibitive activity of dicarboxylates in preventing mild steel corrosion in neutral aqueous solution

Abstract

The efficiency of dicarboxylate corrosion inhibitors for mild steel in near neutral NaCl solution was studied using electrochemical methods as open circuit potential, potentiodynamic polarisation curves and electrochemical impedance spectroscopy. Surface analysis was carried out to determine the kind of protection afforded by these inhibitors and to establish the inhibition mechanism. The results show that adipate and sebacate are good inhibitors, and their effectiveness is strongly dependent on chloride concentration. In the case of sebacate, the concentration required for inhibition was determined, and it was found that full protection strongly depends on the chloride concentration. Furthermore, it was shown that the mixture of benzotriazole with these dicarboxylates significantly improves the inhibition performance. The combination of these inhibitors exhibits a synergistic protective effect as it leads to higher efficiencies compared to those obtained when used individually.

Keywords:

• Mild steel
• Corrosion
• Passivation
• Organic inhibitor
• Dicarboxylate
• Benzotriazole

This work was performed within the framework of the project called ‘Clearzinc’ financed by the European Union (European Regional Development Founds) and the Région Wallonne. The authors would like to thank V. Huart, A. Roobroeck, D. Cossement, F. Renaux and Y. Paint for their help.