Corrosion Inhibition by Pumpkin Peels Extract in Petroleum Environment

The corrosion inhibition of carbon steel in petroleum environment by ethanolic extract of pumpkin peels has been studied in relation to three concentrations of the inhibitor include 3, 5 and 7mL/L at four temperatures over the range 50–80°C using electrochemical measurements (open circuit potential measurements and galvanostatic polarization). The results were supplemented with optical microscopy and FTIR spectroscopy. All the methods employed are in reasonable agreement. Inhibition efficiencies were calculated and the results show that 5mL/L of pumpkin peels extract gave the best inhibition which ranged from 72.4 to 75.7%. Thermodynamics of adsorption (enthalpy of adsorption, the entropy of adsorption and Gibbs free energy) were calculated and discussed. Thermodynamic functions of adsorption processes were calculated from experimental polarization data and the interpretation of the results reveals that this pumpkin peels extract obey Langmuir adsorption isotherm. Polarization curves indicate that green inhibitor is a mixed type inhibitor, which decreases both Tafel slopes.