Effect of Santolina pectinata (Lag.) Essential Oil to protect against the corrosion of Mild steel in 1.0 M HCl: Experimental and quantum chemical studies

The essential oil of Santolina pectinata aerial parts (SP oil) was extracted by hydrodistillation and analyzed by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC/MS). 34 components were identified, accounting 59.4% of the total oil, which (Z)-heptadeca-10,16-dien-7-one (ZHD) was the major component with 28 % of the oil. The protective effect of this oil on the corrosion of mild steel (MS) in 1M HCl solution was tested by the measurements of Weight loss (WL), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS). From WL measurements, the inhibiting effect was raised with the increasing of both concentration inhibitor and temperature. PDP curves led to a mixed-type inhibitor. The charge transfer process mainly controls the results of EIS measurements. The SP oil adsorption not only was discovered to obey Langmuir isotherm but showed a chemical interaction as well. The computational methods such as density functional theory (DFT), Monte Carlo (MC) and radial distribution function (RDF) simulations were also performed to analyze the possible contribution of (Z)-heptadeca-10,16-dien-7-one (ZHD) to the corrosion prevention effect of global oil.