Abstract
The effect of dried Shazab leaf extract (DSLE) as a green, eco-friendly corrosion inhibitor for 420 stainless steel (420 SS) in 0.5 M HCl was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic Tafel polarisation (PTP). Four types of isotherm models were applied to calculate the equilibrium adsorption constant (Kads), and based on the value of the correlation coefficient (R2), the Langmuir isotherm was found to be the best in this study. Moreover, based on the different thermodynamic parameters such as Gads, Hads, and Ea, the adsorption of DSLE on 420 SS was considered to be a physisorption process, and the adsorption was proved using FTIR and UV-vis spectroscopy. The degree of pitting that appeared on the metal surface was investigated in different concentrations of HCl and examined using microscopic photographs. Finally, the inhibition mechanism was studied.