Theoretical and Experimental study of the corrosion inhibition of mild steel in acid medium using some surfactants of the essential oil of FoeniculumVulgare bulb

Corrosion inhibition by foeniculum vulgare bulb (fvb) essential oil on mild steel was studied in 1 m hcl solution by using the electrochemical techniques and the weight loss measurements. the results obtained clearly revealed that fvb extract behaves as a mixed-type inhibitor and adsorbed physically onto the mild steel surface. the inhibition efficiency increased with increasing concentration of fvb and finally reached 89.2% at 303 k,this behavior decreased with increase in temperature. the most noteworthy inhibition efficiency was affirmed by identification of the film formed on the metal surface by using the scanning electron microscopy (sem) and energy dispersion x-ray spectroscopy (edx). the analysis of the chemical composition of the oil allows determining the major constituents all of which are in the form of oxygenated monoterpenes whose trans anethole is the major compound,these molecules are fully optimized by using gradient corrected dft at b3lyp/6-31g level with gaussian 09 program,in order to determine the structural and electronic parameters of the molecule responsible for imparting on the extract its high inhibition efficiency. © 2017,university of mohammed premier oujda morocco.