Langmuir Adsorption Isotherms and Reaction Number Evaluation for Mild-Steel in Aqueous Solution of Binary Acid Mixture in Presence of Toluidine Isomers

摘要

Corrosion behavior of mild-steel in binary acid (HCl + HNO_3) mixture has been examined using conventional weight-loss and thermometric techniques in presence of substituted aniline Compound viz. o-toluidine, p-toluidine and m-toluidine. These inhibitors obey Langmuir adsorption isotherm equation, (ⅰ) Reaction Number (RN), (ⅱ) temperature difference as well as (ⅲ) time to reach T_(max) were calculated by thermometric technique. Inhibition efficiency determined from the results of conventional weight-loss and thermometric techniques are in good agreement for toluidine isomers used in the binary acid mixture. The mode of inhibitive action appears to be chemisorption. Toluidine isomers can be arranged in the following order of efficiency in inhibiting corrosion of mild-steel, o-toluidine > m-toluidine > p-toluidine Comparatively higher inhibition efficiency by o and p-isomer of toluidine can be attributed to the tendency for surface protonation due to high hydrogen over voltage on metal surface.