PERFORMANCE OF METHANOL EXTRACT OF Kalanchoe crenata LEAVES ON CORROSION OF MILD STEEL IN 5.0 M ACID MEDIUM.

The inhibitive performance of the methanol extract of an eco-friendly green inhibitor Kalanchoe crenata (KC) leaves on the corrosion of mild steel in 5.0 M H2SO4 solution with inhibitor concentrations of 1 g/L, 2 g/L, 3 g/L, 4 g/L and 5 g/L, at the temperatures of 333 K and 353 K was studied using gravimetric (weight loss) and gasometric (hydrogen evolution) techniques to determine its inhibition efficiencies as well as to depict the mechanism of inhibition of the inhibitor. The gravimetric technique was done for 5 Hours. Results indicate that the leaf extract inhibited the corrosion process efficiently. The extract showed inhibition efficiency of 84.95% and 84.24% (333 K) for gravimetric and gasometric analysis respectively. The Inhibition efficiency was found to increase with an increase in the extract concentration and also increased with an increase in time but decreased with increase in temperature. Thermodynamic considerations revealed that the activation energy, Ea increased in the presence of the plant extract. The kinetic data confirmed the reaction process to be first order. Adsorption of the plant extract on mild steel surface is an exothermic process and spontaneous as deduced by negative Qads mean value (-10.39 kJ/mol) and negative ∆Gads values (-11.54 and -10.49 kJ/mol). The mechanism of adsorption proposed for the plant extract on the mild steel surface is physical adsorption. Experimental data obtained fits the Langmuir adsorption isotherm.