Abstract:
Fatty acid molecules 9,12,15-octadecatrienoic acid (C18:3), 9,12-
octadecadienoic acid (C18:2), and hexadecanoic acid (C16:0) possessing active
functional groups with the capability of fast electron transfer have been
established for effective corrosion inhibition of mild steel. In this regard, a
microalga Scenedesmus sp. is isolated and its fatty acids have been studied to
corroborate the adsorption behavior, attributing the anticorrosion efficacy on
mild steel in 1 M HCl solution by forming metal−inhibitor framework.
Electrochemical analysis has been used to ascertain the surpassing corrosion
inhibition efficiency at an optimal concentration of 36 ppm with maximum 95.1%
inhibitive performance. The results of metallography with or without the inhibitor
molecules have indicated significant changes in surface morphology of mild steel
specimen for gradual enhancement in immersion time (72 h). Hydrogen
evolution reaction has been emphasized to observe the tendency of significant
decrease in the bubble formation in the presence of inhibitor compared to 1 M
HCl solution only. Surface morphometric studies (scanning electron microscopy and atomic force microscopy) have also
revealed the excellent adsorption capacity of Scenedesmus fatty acids on metal surface. Quantum chemical calculations,
performed by density functional theory, determined significant adsorption effectiveness, based on the donor−acceptor capability
between metallic surface and inhibitor molecules.
