Inhibitive effect of black pepper extract on the sulphuric acid corrosion of mild steel

The corrosion inhibitive effect of the extract of black pepper on mild steel (MS) in 1 M H2SO4 media was evaluated by conventional weight loss studies (303-323 K), electrochemical studies viz., Tafel polarization, ac impedance and scanning electron microscope (SEM) studies. Results of weight loss study reveal that black pepper extract acts as a good inhibitor even at high temperatures also. The inhibition is through adsorption which is found to follow Temkin adsorption isotherm. Tafel polarization method revealed the mixed mode inhibition of black pepper extract. Analysis of impedance data has been made with equivalent circuit with constant phase angle element for calculation of double layer capacitance value. SEM studies provide the confirmatory evidence for the protection of MS by the green inhibitor. (C) 2008 Elsevier B.V. All rights reserved.