The inhibition of 4-(2′-amino-5′-methylphenylazo) antipyrine on corrosion of mild steel in HCl solution

The effect of 4-(2'-amino-5'-methylphenylazo) antipyrine (AMPA) on the corrosion of mild steel in a 2 M HCl solution was studied using weight loss and potentiodynamic polarization techniques. All of the data reveal that AMPA acts as an inhibitor in the acid environment; furthermore, polarization data show that the compound behaves as a mixed-type inhibitor. It was found that the inhibition efficiency increases with an increase in AMPA concentration but decreases with an increase in temperature. Flory-Huggins adsorption isotherm and El Awady thermodynamic-kinetic model fit the experimental data of the studied compound. Thermodynamic parameters for corrosion and adsorption processes were obtained from experimental data of the temperature studies. (C) 2001 Published by Elsevier Science B.V.