Electrochemical Investigation of Coconut Oil as Green Corrosion Inhibitor for ST37 Carbon Steel Protection

Document Type: Research Paper



The corrosion inhibition of ST37 Carbon Steel in 1.0 M HCl by aquatic extract of coconut has
been studied as a possible source of green inhibitor using the potentiodynamic polarization
and electrochemical impedance spectroscopy techniques. The aquatic extract of coconut have
many advantages over classical techniques of sample preparation of plant gums (such as
drying and solvent reflux).Polarization measurements showed that the extracts act as mixed
typed inhibitor but under cathodic control. The passivation layer formed on metal surface,
and then inhibits the anodic dissolution of steel. The compounds that available in coconut
oil provides a good protection to steel against corrosion by shifting the potential at the noble
direction. The Nyquist plots showed that on increasing CW concentration, increases charge
transfer resistance and decreases double layer capacitance. The Results obtained from Tafel
extrapolation and EIS techniques were in good agreement. SEM studies also help to understand
the changes that take place on the surfacelayer with respect to change in CW concentration.