Synthèse et Caractérisation Physicochimique de Bases de Schiff : application dans la Protection Contre la Corrosion des Armatures du Béton

Abstract

Two original Schiff bases named L1 and L2 were synthesized using the condensation method and characterized by (FT-IR, XRD, EA). The compounds obtained are single crystals. The study of their inhibitory efficiencies towards the corrosion of reinforcement concrete was carried out by potentiodynamic polarization and impedance spectroscopy (EIS). The inhibition efficiency of L1 and L2 against the corrosion of mild steel in concrete is studied in the aggressive medium 0.5M NaCl as a function of the inhibitor concentration, the immersion time and the temperature. A high inhibition power is observed (90% for L1=10-6M and 93% for L2=10-4M) at t=28days and T=30°C. This inhibition increases as a function of temperature for the two Schiff bases. The mechanism of action of these inhibitors is defined by the thermodynamic study. Inhibitory efficiency (EI%) and apparent activation energy (Ea) were calculated in the absence and in the presence of different concentrations of L1 and L2. The values of ΔGads, Ea, ΔHa, and ΔSa show that L1 and L2 are good inhibitors of corrosion of mild steel in concrete in a 0.5M NaCl environment. The inhibitors studied act with an adsorption process according to chemisorptionprocess obeing the Langmuir isotherm. The functional density theory (DFT) has been used. The found results are in good agreement with the experimental one. Mechanical tests were carried out to examine the effect of the addition of these two inhibitors on the mechanical strength of reinforced concrete. No alterations were observed. Therefore, we conclude that these compounds are promoters in the field of Civil Engineering