Visual Abstract
Lead is corroded by dilute (<0.4 M) hydrochloric acid solution because of the formation of soluble lead ions. In concentrated (>0.4 M) solution, corrosion is inhibited by the formation of a protective PbCl2layer. The influence of a new series of organic amines as suppressants of lead corrosion in such media was studied using potentiostatic and cyclic voltametry techniques. The inhibitors used were pyrazole derivatives of the following structure:
where X =H (parent compound [PP]) = 3(5)amino, 5(3)phenyl pyrazole). The derivatives were X = CH3, OCH3, and Cl. The current-potential curves were plotted for both cathodic and anodic processes. The data obtained gave the inhibition efficiencies of the various amines. The ρ-methyl derivative was found to be the most effective inhibitor because of the electron-repelling nature of the methyl group. The ρ-Cl and ρ-OCH3derivatives, on the other hand, have lower efficiencies, probably because of the −I effect of the substituents.
