Investigation of Inhibition Mechanism of Three Carboxylate-Based Organic Compounds on the Corrosion Behaviour of Carbon Steel in a Simulated Concrete Pore Solution Contaminated with 3/5 wt% NaCl

In this study, the effects of Tri-sodium citrate, Sodium potassium tartrate and Ethylene di-amine tetra-acetic acid as organic corrosion inhibitors on the corrosion behavior of carbon steel in a simulated concrete pore solution contaminated with 3.5 wt% NaCl, were investigated through open circuit potential, Electrochemical impedance spectroscopy and Cyclic polarization analysis. Morphology and surface roughness of the specimens was evaluated by scanning electron microscopy. EIS analysis showed that after 48 hours of exposure to NaCl solution, the citrate and tartrate were able to achieve 91.2% and 87.3% corrosion inhibition efficiency at their best performance respectively. Inhibition Mechanism of each inhibitor was analyzed Based on the parameters obtained from the EIS tests. According to Cyclic polarization results, the dominant mechanism of inhibition is through aggregating on anodic sites and consequently limiting the anodic reactions. SEM images showed that the addition of 0.1 M of citrate or tartrate to the corrosive medium, causes a relatively persistent layer on the surface of the metal with low porosity level which immunes the carbon steel from pitting corrosion to a large extent.