A new corrosion inhibitor for steel rebar in concrete: Synthesis, electrochemical and theoretical studies

An original Schiff base 4(3-Hydroxy-naphthalen-2-ylimino)-pentan-2-one (L-2) was synthesized by condenzation of 3 amino 2-naphtol and acetylacetone in methanol. The inhibition effect of this coumpound against the corrosion of rebar immersed in 0.5 M NaCl solution was investigated. The XRD analysis confirms the formation of the Schiff base. The electrochemical study was performed using potentiodynamic polarization and impedance measurement spectroscopy. The thermodynamic and electrochemical results show that this organic product is a good inhibitor and acts by adsorption according to a chemisorption process obeying the Langmuir isotherm. The morphological investigations by scanning electron microscopy (SEM) coupled with EDS carried out assert the electrochemical results. The mechanical study reveals good resistance to bending and compression in the presence of a low concentration of the Schiff base. In order to extract the quantum chemical parameters and elucidate the ability of this organic molecule to inhibit the corrosion, the density function theory (DFT) is used. The theoretical and experimental results corroborate. (C) 2020 Elsevier B.V. All rights reserved.