Sweet Clover Leaves as Green Inhibitor in Petroleum Medium

. This work involves the study of the corrosion inhibition of steel in petroleum medium using alcoholic extracted of Sweet Clover leaves SC with four concentrations of extracted (1, 3, 5 and 7mL/L) at four temperatures over the range 50 – 80 o C. Inhibition efficiency IE% results show that 3 mL/L the best concentration which they gave efficiencies in the range of 73.2–83.9%. Thermodynamic functions of adsorption processes were calculated from experimental polarization data and the interpretation of the results reveals that Ficus carica extract SC extract obey Langmuir adsorption isotherm. Polarization curves indicate that SC extract is a mixed type inhibitor. The small values of K ads refer to physical adsorption process. The values of Δ G oads , Δ H oads and Δ S oads were negative indicating the spontaneous and exothermic adsorption process as well as SC extract retained the metal ions and reducing the dissolution of steel and the activated complex in the rate determining step denotes an association rather than a dissociation step.