Experimental, Quantum Chemical and Molecular Dynamic Simulations Studies on the Corrosion Inhibition of C38 Steel in 1M HCl by Anethum graveolens Essential Oil

The essential oil from the seeds of Anethum graveolens (AGEO) was studied by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC/MS). 12 components were identified accounting 98% of the total oil, which Carvone (43.5%), Dillapiol (26.7%) and Limonene (15.4%) were the major compounds. The use of AGEO as a C38 steel corrosion inhibitor in 1 M HCl solution was studied by weight loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. AGEO acted as a highly efficient mixed-type inhibitor. Adsorption of the inhibitor on the steel surface followed Langmuir adsorption isotherm. The calculated adsorption thermodynamic parameters were calculated and discussed. Quantum chemical calculations and molecular dynamic simulations were also carried out in order to correlate the inhibitory effect of AGEO and the electronic properties of its major constituents, and to provide some indications into the nature of their interaction with the metal surface at a molecular level.