KI effects on corrosion inhibition for 1018 steel in acid media using Medicago sativa

Abstract

Medicago sativa (M. sativa) extract is a safe and eco-friendly corrosion inhibitor of 1018 steel in acid media. The inhibitor reached a maximum efficiency of 85% by using 500 ppm. In this work, we study the use of KI as an add-on to increase the inhibition efficiency of M. sativa, as well as making the natural inhibitor competitive with the commercial ones. We evaluated the effect of halide ions through the variation of different concentrations of KI and its synergy with the extract of M. sativa as a corrosion inhibitor of carbon steel in 0.5 M sulfuric acid and at different temperatures. The results were obtained through electrochemical techniques such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) curves, and weight loss gravimetric technique. It was found that halide ions increase the inhibition efficiency of M. sativa from 85 to 95% when 5 mM concentration of KI was used. The efficiency of the inhibition increases proportionally with the immersion time but reduces when the temperature increases. The addition of iodide ions (I−) revealed that it exerts a synergistic effect on the inhibition of corrosion with the extract of M. sativa. However, when studying the metal surface using a scanning electron microscope, pitting corrosion was found.

Experimental and Theoretical Studies of Tailor-made Schiff Bases as Corrosion Inhibitors for Carbon Steel in HCl

“…Zehra et al 44 investigated a glycine derivate (100 ppm) as a corrosion inhibitor blended with 5 ppm with sodium dodecyl sulfate or cetyl pyridinium chloride in HCl 1 M, reaching efficiencies for potentiodynamic tests of 92.84% and 96.36%, respectively, while the sole analysis of the corrosion inhibitor yielded an efficiency of 88.64%. The synergism parameter was calculated according to the relationship given by Aramaki and Hackerman that was reported elsewhere 45,46 .…”

Synergistic Effect of Benincasa hispida Peel Extract and KI on the Corrosion Inhibition of Mild Steel in HCl

“…The synergistic effect is characterized by the enhanced activity that occurs when two or more chemical substances interact, compared to their individual effects [25][26][27]. Halide ions (Cl − , Br − , I − ) can act as bridges between the inhibitor molecules and the metal surface due to their high electronegativity, which makes it easier for the inhibitor molecules to adsorb on the metal surface [28,29]. Khadiri et al [21] discovered that the combination of Punica granatum extract and KI significantly increased the corrosion inhibition of S355 steel in 1 M HCl solution.…”