Corrosion Inhibition of Carbon Steel in Acidic Environment by Papaya Seed as Green Inhibitor

Abstract

Chemicals used presently for corrosion inhibitors in Industries are highly toxic to both human beings and environment. These inhibitors may cause the damage to organ system viz., kidneys or liver, or to disturb a biochemical process of an enzyme system at some site in the body. For papaya seed, a vegetable waste is found to act as a very good green inhibitor, in preventing acid corrosion of low-carbon construction steel. The study was made in 0.5 to 3 N H2SO4 with the variation of concentration. An increase in inhibitor concentration decreases the rate of degradation. But there is an optimum concentration at which the inhibitor effect is maximum, beyond that the corrosion rate again increases. The adsorption study shows that the mechanism of corrosion inhibitor is due to physical adsorption, following Temkin adsorption isotherms. Electrochemical impedance spectroscopy study showed that the corrosion inhibition by the papaya seed is due to an increase in polarization resistance and impedance at metal-solution interface.