Alkaloid and Non Alkaloid Extracts of Solanum melongena Leaves as Green Corrosion Inhibitors on Carbon Steel in Alkaline Medium

The corrosion and inhibition behavior of Carbon steel (CS) in high alkaline solution [Sodium trioxocarbonate (IV)] in the presence of alkaloid and non alkaloid extracts of Solanum melongena leaves have been studied using conventional methods - mass loss and gasometric techniques. The results indicate that the extracts inhibit the corrosion of Carbon steel. However, the Alkaloid extract of Solanum melongena leaves (AESML) exhibits higher maximum inhibition efficiency of 81.1% than Non alkaloid extract of Solanum melongena leaves [NAESML] (65.1%) at 3.0 g/L concentration. Inhibition efficiency increase with increasing concentration of extracts but decreased with rise in temperature. Inhibition mechanism was deduced from the activation and thermodynamic parameters that govern the process. Adsorption of extract on the CS was found to obey the Langmuir adsorption isotherm. The phenomenon of physical adsorption is proposed from the obtained thermodynamic parameters.