Origanum majorana Extracts as Mild Steel Corrosion Green Inhibitors in Aqueous Chloride Medium

We optimized Origanum majorana (OM) extraction for mild steel corrosion inhibition in neutral 0.5 M chloride medium. The inhibition mechanism evolved in presence of the optimal extract was discussed when calculating the activation energy (Ea), the activation enthalpy (ΔaH) as well as the activation entropy (ΔaS). The OM extract molecules were investigated using the density functional theory (DFT) at B3LYP/6-31G(d,p) basis set level. 1-methyl-4-propan-2-ylcyclohexa-1,3-diene alpha-terpinene was predicted exhibiting the most inhibition capabilities.