Corrosion and hydrogen permeation inhibition for mild steel in HCl by isomers of organic compounds

Abstract

Abstract Hydrogen permeation and corrosion inhibition characteristics of isomers of phenylenediamine, toluidine, and nitroaniline were studied on mild steel in 1M HCl. The Tafel extrapolation method was used to determine the inhibition efficiency, while the Devanathan–Stachurski technique was used to determine the hydrogen permeation rate. The adsorption of these compounds on mild steel from 1M HCl obeys Langmuir's adsorption isotherm for toluidine and nitroaniline and Temkin's adsorption isotherm for phenylenediamine. Inhibition efficiency was found to be more for isomers of phenylenediamine followed by those of nitroaniline and toluidine. All the isomers of these three organic compounds inhibit the corrosion of and hydrogen permeation through mild steel in HCl in the order ortho > meta > para for phenylenediamine and nitroaniline and meta > ortho > para for toluidine.