Inhibitive Effect by Acid Extract of Ficus Exasperata Leaves on the Sulphuric Acid Corrosion of Mild Steel

N. S. Patel,S. Jauhari,G. N. Mehta

doi:10.1155/2009/413421

Abstract

Extract ofFicus exasperataleaves was investigated as corrosion inhibitor of mild steel in 1 N H2SO4using conventional weight loss, electrochemical polarizations, electrochemical impedance spectroscopy and scanning electron microscopic studies. The weight loss results showed that the extract ofFicus exasperatais excellent corrosion inhibitor. Electrochemical polarizations data revealed the mixed mode of inhibition. The results of electrochemical impedance spectroscopy shows that the change in the impedance parameters, charge transfer resistance and double layer capacitance, with the change in concentration of the extract is due to the adsorption of active molecules leading to the formation of a protective layer on the surface of mild steel. Scanning electron microscopic studies provided the confirmatory evidence of improved surface condition, due to the adsorption, for the corrosion protection.

Highlights

Huge amount of H2SO4 is used in the chemical industry for removal of the undesired scales and rust
Most of the inhibitors are organic compounds with N, S and O hetero-atoms have higher electron density making them the reaction centres. These compounds are adsorbed on the metallic surface and block the active corrosion sites and most of them are highly toxic to both human beings and environment
It is clear that the value of IEw% increases with the increase in the concentration reaching a maximum value of 93% at the highest concentration of 200 ppm, suggesting that the number of molecules adsorbed were increased over the mild steel (MS) surface, blocking the active sites of acid attack and thereby protecting the metal from corrosion

Summary

Introduction

Huge amount of H2SO4 is used in the chemical industry for removal of the undesired scales and rust. It is clear that the value of IEw% increases with the increase in the concentration reaching a maximum value of 93% at the highest concentration of 200 ppm, suggesting that the number of molecules adsorbed were increased over the MS surface, blocking the active sites of acid attack and thereby protecting the metal from corrosion.

Results

Conclusion