Imidazole based compounds as copper corrosion inhibitors in seawater

The effects of imidazole and its structural derivatives: purine, adenine and 6-benzylaminopurine, on copper corrosion in seawater were investigated. Electrochemical methods were chosen for this purpose and the results show that they all act as mixed-type corrosion inhibitors under tested conditions. According to the potentiodynamic polarization results inhibition efficiency at corrosion potential increases in the following order imidazole < purine < adenine < 6-benzylaminopurine, which is in agreement with the expectation that the increase of molecular weight and number of heteroatoms in the molecule leads to the increase of inhibition efficiency degree. In the broader potential range, adenine is more efficient. The mechanism of inhibitor action includes adsorption on copper surface that fits the Langmuir adsorption isotherm. Quantum mechanical calculations indicate that there is a correlation between energy gap and inhibition efficiency.