Abstract Stachytarpheta indica leaf extract inhibited the corrosion of mild steel in 1M H2SO4 solution by both gravimetric and hydrogen evolution methods. The inhibition efficiency increased with increase in the leaf extract concentration and decrease in temperature. Physical adsorption has been proposed for the adsorption of Stachytarpheta indica leaf extract on mild steel surface. The adsorption of the leaf extract obeyed the modified Langmuir adsorption isotherm. The calculated thermodynamic parameters revealed that the corrosion inhibition process was both endothermic and spontaneous.
Keywords Physical adsorption, Langmuir isotherm, Gravimetric, Hydrogen evolution.