Use of an imidazol synthetized from palm oil as a corrosion inhibitor for a supermartensitic stainless steel in H2S

ABSTRACT A no-ionic gemini surfactant, namely bis(2-((2-palmitoamidoetil) amino) etil) 1H-imidazol-4,5-dicarboxilate, 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 H2S. 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. GRAPHICAL ABSTRAC