Corrosion Inhibition of a Carbon Steel by 2-Ethylamino-Ethanol in Aerated 3% NaCl Solutions — Effect of pH

Colorimetric and electrochemical corrosion rate measurement techniques were used to evaluate the efficiency of 2-ethylamino-ethanol in corrosion inhibition of a carbon steel in aerated 3% NaCl solutions. It was shown that, for inhibitor concentrations above 310 ppm, the high pH value of the solutions is by itself responsible for a partial 40% efficiency in corrosion protection, as compared to an overall efficiency of about 90%. In order to differentiate the intrinsic inhibiting action of 2-ethylamino-ethanol, another efficiency definition is proposed as a differential efficiency, in which the influence of the pH is eliminated. The obtained differential values range from 70 to 80%. This high activity of the inhibitor may be interpreted both by its ability to stabilize the hydroxide surface film and by its adsorption onto bare sites of the metal.