Corrosion inhibition of XC48 steel by Grewia bicolor jus leaves extract in 1M HCL acid medium: electrochemical and gravimetric study

The inhibitory effect of the methanol extract of Grewia bicolor juss (GB) leaves against XC48 mild steel corrosion, in hydrochloric acid solution (1M) medium, was investigated by potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods for different concentrations at 298 K and weight loss measurements with optimum concentration at different temperatures (298-333 K) and time immersion. The results demonstrated that the components of the extract took action mainly as a mixed-type inhibitor, and the inhibition efficiency values escalated with the progression of extract concentration. The maximum value obtained is about 93% at a concentration of 1500 ppm. This high efficiency can be attributed to the installation of a protecting blanket on the electrode surface. The adsorption of the inhibitor molecules on adsorbate surface obeyed Langmuir isotherm model. The thermodynamic parameter values suggested that physisorption and chemisorption constituted the major contribution to the process of adsorption. Results obtained from weight loss measurements show that the inhibition efficiency decreases with increasing immersion time and temperature. Finally, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analyses confirmed obtained results, which reveal that adsorbed inhibitor molecules hinder HCl attacks at the steel grain boundaries.