The role of keto group in cyclic ligand 1,4,8,11-tetraazacyclotetradecane-5,7-dione as strong corrosion inhibitor for carbon steel surface: Experimental and theoretical studies

Abstract

The performance of 1,4,8,11-tetraazacyclotetradecane (L1) and 1,4,8,11-tetraazacyclotetradecane-5,7-dione (L2) as corrosion inhibitors was investigated electrochemically, showing that inhibitor L2 acts effectively as it yields low polarization currents with high impedance loop diameter. The metal surface analyzed by SEM, EDS and AFM reveals that deep holes observed in HCl alone were not seen in the presence of inhibitors, maintaining the content of Fe in the steal about 95% without detecting oxygen in EDS. The adsorption of inhibitor with the metal (186 Fe atoms) was studied theoretically, observing there is a strong interaction between L2 and metal than for L1.