Corrosion Mechanism of Low-Carbon Steel in Industrial Water and Adsorption Thermodynamics in the Presence of Some Plant Extracts

The effects of radish leaves and black cumin as plant extracts on the corrosion behavior of low-carbon steel in industrial water in the temperature range of 30 to 80 A degrees C and velocity range of 1.44 to 2.02 m s(-1) using potentiodynamic polarization, electrochemical impedance spectroscopy, and mass loss measurements have been investigated. The inhibition efficiency increased with increasing concentration of the plant extracts up to a critical value but it slightly decreased with increasing temperature. Inhibition efficiency values obtained from mass loss and potentiodynamic data were in reasonable agreement. Potentiodynamic polarization clearly indicated that radish leaves and black cumin extracts acted as anodic inhibitors. The adsorption behavior was found to obey the Flory-Huggins isotherm model. The associated activation parameters and thermodynamic data of adsorption were evaluated and discussed. The results show that radish leaves and black cumin could serve as effective inhibitors for low-carbon steel in industrial water media, with black cumin providing better protection than radish leaves.