Leaves Extract of Cajanus Cajan (Pigean pea) as Corrosion Inhibitor for Mild Steel in Simulated Seawater Environment

There is a new direction in research towards the use of plant of natural origin as corrosion inhibitors for metals and alloys. Sequence to this, the corrosion inhibition of mild steel in 3.5% sodium chloride (NaCl) solution by cajanus cajan leaves extract has been studied using weight loss technique. The corrosion rates of the studied samples were found to decrease with increase in concentration of the inhibitor. The inhibition efficiency also increases with the increase in the extract concentration and decreased with increase in temperature. Thermodynamic parameters show that the inhibition is through adsorption of plant extract onto the metal surface and it obeys Langmuir adsorption isotherm and occurs spontaneously. The activation energy as well as other thermodynamic parameters for the inhibition process was calculated and these thermodynamic parameters show strong interaction between inhibitor and mild steel surface.