Contribution to understanding synergistic effect of Punica granatum extract and potassium iodide as corrosion inhibitor of S355 steel

Abstract The inhibition effectiveness of Punica granatum ( also called Pomegranate) extract and the synergistic effect of potassium iodide (KI) against the degradation of mild steel in 1 M HCl was studied. Potentiodynamic polarization measurement (PDP) was used in order to investigate the performance of this compound. The presence of a mixture of iodide ions (KI) and inhibitor (PG) increased the degree of surface coverage. Also, the inhibition efficiency reaches 82% at 323 K when the concentration of P. granatum (PG) is 2 mg/L with 10 mM of KI. The synergistic effect between the inhibitor and KI could be explained by the reinforcement of the layer being adsorbed onto the steel surface. The adsorption of inhibitor onto the steel surface followed the Freundlich adsorption isotherm. Characterization techniques, such as scanning electronic microscopy coupled with energy dispersive X–ray spectroscopy (SEM/EDX), Raman, and ultra-violet-visible (UV-visible) spectroscopies, confirm the adsorption of inhibitor onto the surface morphology.