Corrosion inhibition and adsorption behaviour of 4-aminoantipyrine on mild steel in H<inf>2</inf>SO<inf>4</inf>

Abstract

Weight-loss measurements and potentiodynamic polarization studies show that 4-aminoantipyrine (AAP) acts as an inhibitor for the corrosion of mild steel in 2M H2SO4 solution. The inhibition efficiency increases with the inhibitor concentration, but decreases with temperature. The inhibition of AAP is due to its adsorbance and blocking the active sites of the metal surface without affecting the corrosion mechanisms: AAP behaves mainly as an anodic inhibitor. The Flory-Huggins isotherm and the kinetic model of El-Awady et al. fit the experimental results well. In the paper, the thermodynamic parameters for dissolution and adsorption processes are calculated and discussed.