Inhibitive effect of Leaves Extract of Coccinia Indica on the Corrosion of Mild Steel in Hydrochloric Acid

The inhibitive effect of the acid extract of Coccinia indica (CI) leaves on the corrosion of mild steel (MS) in hydrochloric acid medium was studied using weight loss and electrochemical methods. The inhibition efficiency increased with increase in concentration of the extract but decreased with rise in temperature. Furthermore, the inhibition efficiency synergistically increased on the addition of halide ions. Polarization measurement studies revealed that CI extract behaves as a mixed inhibitor. Physical adsorption mechanism is proposed from the trend in inhibition efficiency with the change in temperature and from thermodynamic parameters. It has been found that the adsorption of CI on MS complies with Langmuir and Temkin adsorption isotherms. FTIR confirmed the adsorption of CI on MS surface.