Inhibitive effect of N,N'-Dimethylaminoethanol on carbon steel corrosion in neutral sodium chloride solution, at different temperatures

The inhibition of carbon steel corrosion in neutral sodium chloride solution by N,N'- Dimethylaminoethanol (DMEA), at different temperatures, was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results obtained confirm that DMEA is a good organic corrosion inhibitor for carbon steel in 0.5M of NaCl (concentration encountered in the Mediterranean seawater), over the whole range of temperatures studied. The inhibition efficiency (IE%) increases with increasing DMEA concentration; it reaches highest value for a concentration around 0.125 mol.L-1. Potentiodynamic polarization data show that, the compound studied in this research predominantly act as anodic-type inhibitor. The EIS study reveals that the addition of DMEA decreases the corrosion rate of carbon steel in neutral sodium chloride solution, due to the fact that the inhibitor molecules are strongly adsorbed on the active sites following Langmuir isotherm, thus leading to the formation of a stable protective film on the steel surface which is able to keep the metal/solution interface in a passive state. Furthermore, the values of the activation parameters, i.e. ΔHa and Ea obtained in this study indicate that the adsorption process of DMEA is endothermic and could be mainly attributed to chemisorption, respectively.