Chemical Composition and Anti-Corrosive Activity of Pulicaria Mauritanica Essential Oil Against the Corrosion of Mild Steel in 0.5 M H2SO4

Essential oil of aerial parts of Pulicaria mauritanica was obtained by hydrodistillation and analyzed by GC and GC/MS. This oil was tested as corrosion inhibitor of mild steel in 0.5M H2SO4 using weight loss measurements, electrochemical polarization and EIS methods. The analysis of P. mauritanica essential oil allowed the identification of 25 components, which accounted for 94.3% of the total oil which Carvotanacetone was the predominant compound constituting 87.3%. The inhibitory effect of this essential oil was estimated on the corrosion of mild steel in 0.5M H2SO4 using electrochemical polarisation and weight loss measurements. The corrosion rate of mild steel is decreased in the presence of essential oil. The inhibition efficiency was found to increase with oil concentration to attain 91.5% at 2g/L. Polarisation curves revealed that this oil act as mixed type inhibitor with a strong predominance of cathodic character. The temperature effect on the corrosion behaviour of mild steel in 0.5M H2SO4 without and with the inhibitor at 2 g/L was studied in the temperature range from 303 and 343 K. The adsorption of inhibitor onto the mild steel surface was found to be a spontaneous process and to follow the Langmuir adsorption isotherm. The associated activation energy has been determined.