The influence of aniline and its derivatives on the corrosion behaviour of copper in acid solution: a theoretical approach

A theoretical study of some aniline derivatives toward corrosion of copper in hydrochloric acid was carried out using cluster models for aniline-copper surface systems and ab initio Hartree Fock calculations. This study showed that the interaction of aniline molecules is highly favored in surface defects like the corner. The adsorption energy increases in several orders of magnitude rising from 30 to 67 kcal/mol. The interaction occurs between the surface defect and the amino group of the aniline molecule. The adsorption energy increases with anilines possesing electron donor substituents and decreases with anilines possessing electron acceptor substituents. These results showed that the corrosion inhibition by aniline molecules can be associated mainly to local properties acting on highly active sites, like defects, present in the copper surface. In addition, the possibility of ion pair formation between protonated aniline and chloride ion, and its influence on the general adsorption of aniline on copper is also analyzed.