Evaluation of the inhibitive effect of essential oil of Lavandula multifida L., on the corrosion behavior of C38 steel in 0.5 M H2SO4 medium

Abstract

The essential oil of the aerial parts of Lavandula multifida L., collected in Errachidia region (three samples) in southeast Morocco, was extracted by hydrodistillation and analyzed by GC and GC-MS. The oil was predominated by carvacrol (57.9–59.0%). L. multifida oil was tested as corrosion inhibitor of C38 steel in 0.5 M H2SO4 using weight loss measurements, electrochemical polarization, and EIS methods. The results obtained by measurements of weight loss showed that inhibition efficiency increases with inhibitor concentration to attain 72.2% at 2 g/l of oil at 298 K. Polarization curves revealed that L. multifida oil acts as mixed type inhibitor. The temperature effect on the corrosion behavior of steel in 0.5 M 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 on the C38 steel surface was found to be a spontaneous process and to obey Langmuir’s adsorption isotherm. The associated activation energy has been determined.