Inhibition of C-steel Corrosion by Green Tea Extract in Hydrochloric Solution

Inhibition ability of green tea extract (GTE) on the C38 steel (CS) in 1.0 M HCl was evaluated using different methods such as: weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods at various temperatures. Polarisation curves show that GTE acts essentially as mixed-type inhibitor controlling cathodic and anodic reactions with slight predominant in cathodic branches. EIS results indicate the increase of resistance transfer (R-t) while double layer capacitance (C-dl) decrease in the rise of green tea extract (GTE) concentrations. Obtained results also showed that the inhibition efficiency decreased with a rise in the temperature. Activation energy (E-a), enthalpy (Delta H-a*) and entropy and (Delta S-a*) of corrosion process were estimated using experimental measurements.