Helichrysum italicum subsp. italicum Essential Oil as Environmentally Friendly Inhibitor on the Corrosion of Mil Steel in Hydrochloric Acid

Essential oil of aerial parts of Helichrysum italicum subsp. italicum was obtained by hydrodistillation and analyzed by GC and GC/MS. 54 compounds accounting for 97.1 % of the oil were identified. This essential oil was characterized by having a high content of oxygenated monoterpenes (45.9%) with neryl acetate was a major compound (31.0%). The essential oil was also chromatographed by an automatized flash chromatography system. The inhibition of the corrosion of mild steel in Hydrochloric acid solution by HI essential oil and its various fractions have been studied using weight loss measurements. Inhibition was found to increase with increasing concentration of the essential oil to attain 82.33 % at 2g/L. The effect of temperature on the corrosion behavior of mild steel in 1M HCl without and with the HI oil at 2 g/L was also studied. The inhibition was assumed to occur via adsorption of the inhibitor molecules on the mild steel surface according to the Langmuir adsorption isotherm. The thermodynamic parameters for activation and adsorption processes were calculated and discussed. The results obtained showed that the HI essential oil could serve as an environmentally friendly inhibitor of the corrosion of mild steel in Hydrochloric acid media.