Evaluation of corrosion inhibition of carbon steel in 1M HCl medium by essential oil of seed Carum Carvi

The inhibiting effect of essential oil of carum carvi (carum. c) on the corrosion of carbon steel in 1m hcl solution has been investigated by different techniques such as weight loss,potentiodynamic polarization and electrochemical impedance (eis) methods at different concentrations of inhibitor ranging from 0,6 to 3 g/l. essential oil from carum carvi was obtained by clevenger-type water distillation. the essential oil was identified by gas chromatography-mass spectrometry (gc and gc/ms). the major compounds identified are: carvone (67.3 %) and limonene (28.8 %). the results of polarization show that the inhibition efficiency increases with increasing the carum. c oil concentration to attain a maximum value of 92 % at 3 g/l. the nyquist plots showed also that increasing oil concentration,charge-transfer resistance increased and double-layer capacitance decreased,involving increased inhibition efficiency. the study of the effect of the temperature (303-343 k) on the behavior of the carbon steel in 1m hcl medium with and without inhibitor reveals that the inhibition efficiencies decreases slightly with temperature increasing. carum. c oil is adsorbed on the steel surface according the langmuir isotherm model. the parameters (ea*,δga*,δha* and kads) were estimated and discussed. physical adsorption is proposed for the corrosion inhibition mechanism and the process followed the kinetic/thermodynamic model of el-awady et al. in the temperature range from 303 to 343 k.