Gordana Pustaj

Inhibition properties and adsorption behavior of olive leaf extract on N80 carbon steel in CO2-saturated brine solution

Abstract The inhibition effect of olive leaf extract on corrosion of carbon steel in brine solutions saturated with CO2 was investigated at 25 °C and 65 °C by means of Tafel polarization, weight loss measurements and Fourier transform infrared spectroscopy. The experimental results reveal that the olive leaf extract has a good inhibition effect on the carbon steel in CO2-saturated brine solution at both temperatures. Tafel polarization investigations revealed that olive leaf extract acted as a mixed inhibitor showing anodic and cathodic behavior. The adsorption of olive leaf extract on carbon steel surface obeyed the Langmuir adsorption isotherm. The adsorption thermodynamic parameters indicated the physisorption of olive leaf extract on carbon steel surface was a spontaneous and exothermic process with an increase in entropy. Fourier transform infrared spectroscopy spectra showed types of bonding for olive leaf extract on the carbon steel surface.

Olive Leaf Extract as a Corrosion Inhibitor of Carbon Steel in CO2-Saturated Chloride– Carbonate Solution

In the present study corrosion inhibition of carbon steel in CO2-saturated chloride– carbonate solution by the olive leaf extract has been researched. For that purpose the electrochemical and spectrophotometric techniques such as potentiodynamic polarization, electrochemical impedance spectroscopy and Fourier transform infrared spectroscopy were employed. Both electrochemical techniques, potentiodynamic polarization and electrochemical impedance spectroscopy, demonstrate that olive leaf extract inhibits the carbon steel corrosion in CO2-saturated chloride–carbonate solution. It was determined that the inhibition efficiency increases with increasing concentration of the olive leaf extract. The olive leaf extract achieves high corrosion efficiency as a mixed type inhibitor, with a prevailing influence on the anode process. Recorded electrochemical impedance spectra in the presence of the extract show the presence of the inhibitor film on the steel surface. This is further confirmed by the recording in Fourier transform infrared spectroscopy spectrum.