Inhibitive Action of Piper nigrum Extract as Corrosion Inhibitor for Mild Steel in 1 N Sulphuric Acid Medium

Abstract

The inhibition effect of Piper nigrum (black pepper) seeds   extracts i.e., acid extract (A) and water extract (W) on the   corrosion of mild steel in 1 N sulphuric acid has been studied   by mass loss and polarization techniques between 302 and   323 K. The inhibition efficiency increased with increase in   concentration of extracts. The corrosion rate increased with   increase in temperature and decreased with increase in concentration   of inhibitor compared to blank. The inhibition efficiency   of the acid extract was greater than aqueous extract (A > W).   The adsorption of inhibitor on the mild steel surface has been   found to obey Temkin's adsorption isotherm. Potentiostatic   polarization results reveal that Piper nigrum act as mixed type   inhibitor. The values of activation energy (E_a), free energy of   adsorption (ΔG_ads), heat of adsorption (Q_ads), enthalpy of   adsorption (ΔH) and entropy of adsorption (ΔS) were also   calculated.