Inhibition effect of 4-amino-antipyrine on the corrosion of copper in 3 wt.% NaCl solution

The effect of 4-amino-antipyrine (AAP) on the corrosion of copper in 3.0 wt.% NaCl was investigated using weight loss, potentiodynamic polarisation, and electrochemical impedance spectroscopy. The results revealed that AAP acts as a mixed-type inhibitor with more pronounced effect on anodic domain and the inhibition efficiency decreases with increasing the temperature. The adsorption of AAP was found to obey the Langmuir isotherm. Surface characterisation was performed using scanning electron microscope and Fourier transform infrared spectrometer. Quantum chemical calculations show that AAP has large negative charge in nitrogen and oxygen atoms, which facilitates the adsorption of AAP on the copper surface.

► 4-Amino-antipyrine (AAP) has inhibition behaviour for copper corrosion in 3.0 wt.% NaCl.
► AAP acted as a mixed-type inhibitor with anodic predominance.
► Adsorption of AAP on the copper surface obeys the Langmuir isotherm.
► Quantum chemical calculations were applied to explain the experimental results.