Inhibitory action of xylenol orange on aluminum corrosion in hydrochloric acid solution

Abstract

The inhibition effect of xylenol orange on the corrosion of aluminum (2S Grade) in 0.4-0.6 M HCL over the temperature range 313-333K has been studied. Both thermodynamic parameters and kinetic parameters with the inhibition effect have been correlated. The inhibition efficiencies of xylenol orange are investigated by weight loss and potentiodynamic polarization methods. The corrosion rate of aluminum decreases with increasing inhibitor concentrations and the efficiency of inhibition increases with increasing concentration of inhibitor up to almost 87% in 0.4M HCL and up to 84% in 0.6M HCL. The concentrations of inhibitor have been kept in the range 2-8 mM. It is also observed that the inhibition efficiency decreases with increasing HCl concentration and temperature. The adsorption of inhibitor on the aluminum surface obeys the Langmuir adsorption isotherm equation. The inhibition effect is satisfactorily explained by both thermodynamic and kinetic parameters. The experimental data have been successfully related with adsorption theory and kinetic equations. Polarization curves show that xylenol orange is a mixed-type inhibitor in hydrochloric acid.