Theoretical basis for the corrosion inhibition feature of Argan oil

Abstract

Natural oils play a pivotal role in corrosion inhibition of various metals and alloys. However, their potential inhibition efficiency in acidic media has been barely investigated from a theoretical point of view. Despite a shared experimental justification, the corrosion inhibition feature of such oils resulted in a sustained debate on how the inhibition mechanism could be related to their ingredients. Given the need to better understand the protection behaviour of Argan oil on carbon steel in molar HCl solutions, the electronic properties of two unsaturated fatty acids, i.e., oleic and linoleic acids were studied by density functional theory (DFT) calculations. The protonated forms of oleic and linoleic acids yielded quantum chemical parameters that confirm linoleic acid to be the most stable unsaturated fatty acid, which seems to be responsible for the inhibition efficiency of Argan oil in acidic medium.