Identification of interaction, surface species and anticorrosion potency for adsorption of myrrh extract on 330 stainless steel in 1 M HCl solution

Steel and its alloys are essential materials in various industries, but they quickly react with the surrounding environment, especially humid ones, which leads to their destruction and corrosion on a large scale. Replacing synthetic organic inhibitors with plant-extracted or natural molecules has recently been a major challenge in terms of environmental and industrial aspects. In this report, the inhibitory dominance, adsorption of myrrh extract (MRE) as a green corrosion inhibitor on 330 stainless steel (SS) in 1.0 M HCl solution at the temperature range of 25 to 55 °C were explored. Weight loss (WL) measurements showed apparent inhibition efficiency (% IE) of MRE of up to 93.6% at 55 °C. The % IE values increased sharply with increasing inhibitor concentration and medium temperature. Adsorption investigations confirmed that the extract molecules were strongly adsorbed on the SS surface and were consistent with the Langmuir and Frumkin models. Polarization monitoring showed that the MRE behaves as a mixed-type inhibitor. EIS was also used to quantitatively evaluate the efficiency of the passive layer on the SS surface. All thermodynamic (Δ<i>H</i>, Δ<i>S</i>, Δ<i>G</i>) and kinetic (<i>K</i> _ads, <i>E</i> _a) parameters were calculated and analyzed. XPS was used to inspect the surface chemistry of SS and the nature of MRE-SS bonds. AFM demonstrated that the SS sample in the blank solution appears to be severely damaged and has the highest roughness of about 382.6 nm, compared to that obtained in the presence of MRE (145.61 nm). Various theoretical and computational methods were used to predict the performance of the examined inhibitor. All experimental findings of the different techniques are in excellent agreement with each other and with theoretical speculations. The outcomes of this study are thought to have some bearing on the sensible development of a potent inhibitor against the corrosion of metals in acidic environments.