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The corrosion inhibition efficiency, g, of sodium (6R,7R)-3-[(acetoxy)methyl]-8-oxo-7-[(2-thienylacetyl)amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, cephalothin, was evaluated in the system API 5L X52/1 M HCl, using electrochemical impedance spectroscopy and SEM analysis. The results showed that the inhibition mechanism involves blockage of the steel surface by the inhibitor molecules through a Langmuir-type adsorption process. The studies to determine the durability where the inhibitor remained effective showed that, at stagnant conditions, the g was maintained over 92% for up to 600 immersion hours at 50 ppm, reaching the best corrosion efficiency when temperature was 25°C. Ó 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

A no-ionic gemini surfactant, namely bis(2-((2-palmitoamidoetil) amino) etil) 1H-imidazol-4,5dicarboxilate, was synthesized from the fatty acids contained in the palm oil and evaluated as corrosion inhibitor for UNS S41425 type supermartensitic stainless steel in presence of H 2 S. Used techniques involved potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance measurements. Additionally, the obtained inhibitor was characterized by Infrared and 1H, 13C RMN spectroscopy. Results have shown that the corrosion rate of the steel was markedly decreased by the addition of the imidazole-type of inhibitor, reaching its maximum efficiency at certain inhibitor concentration, decreasing with a further increase in its concentration. This decrease in the corrosion rate was due to the physical adsorption of the inhibitor on to the steel surface following a Langmuir type of adsorption isotherm, affecting both anodic and cathodic reactions.

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