Effect of Iodide Ions on the Inhibitive Performance of O-, M-, P-Nitroaniline on Mild Steel in Hydrochloric Acid Solution

Abstract

The effect of iodide ions on the inhibitive performance of ortho, meta and para nitro aniline in 1M HCl for mild steel has been studied using weight loss method (gravimetric) measurements at 303 and 333K. Results obtained show that the presence of the nitro aniline compounds in 1M HCl solution inhibits the corrosion process of mild steel. Its adsorption was found to be physical, exothermic and spontaneous as confirmed by values of activation energy and free energy of adsorption (not up to −20 kJ mol⁻¹ for free energy of adsorption and below 80 kJ mol⁻¹ for activation energy) and also fitted the Langmuir adsorption model. Addition of iodide ions synergistically increased the inhibition efficiency of the nitro aniline compounds. Quantitative Structure Activity Relationship (QSAR) approach was used on a composite index of some quantum chemical parameters. The results showed that the Inhibition Efficiency was closely related to some of the quantum chemical parameters.