Synergistic Protection of Mild Steel in Sodium Chloride Solutions Using Mixtures of Sustainable Corrosion Inhibitors

Mild steel material has broad application in marine construction due to its availability, low cost, and high tensile strength. Nevertheless, the major limitation of mild steel is its low corrosion resistance. The use of eco-friendly inhibitors in protecting mild steel from aggressive media is a cheap and practical means competing with conventional phosphate and chromate inhibitors. Herein, the synergistic corrosion inhibition effects between key lime and chlorpheniramine drugs were examined as sustainable inhibitors for mild steel in 24.5 M NaCl solutions through electrochemical measurement, and morphology of the same was characterized using scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM/EDX). The electrochemical investigations revealed that in the presence of 2ml key lime and 8ml chlorpheniramine drug the optimum inhibitive efficiency of 81.82% was achieved, and this is connected to the protecting layer build-up on the surface of the mild steel, thus, blocking the harsh ion diffusion pathway. The polarization plot shows that the inhibitors complex deposition led to the corrosion inhibition mixed-type mechanisms. The SEM/EDX result proved the films formation on the mild steel surface. The adsorption result shows that the inhibitors fit the Langmuir adsorption isotherm.