Electrochemical Studies of Copper Corrosion Inhibition in Aqueous Solution by Basic Red 46 Dye and Evaluation of the Inhibitor Adsorption Behavior

Aims: The corrosion inhibition performance of an organic dye, Basic Red 46, was studied against the corrosion of copper in 1M HCl. The adsorption isotherm of the used dye was also evaluated.

Study Design: Electrochemical methods were used for this study. The corrosion of copper sheets in HCl solution was investigated in the absence and presence of the organic dye.

Place and Duration of Study: Electrochemistry lab., department of physical chemistry, Chemistry Faculty, University of Tabriz, between 2009 to 2010.

Methodology: Electrochemical Impedance Spectroscopy, EIS and Tafel Polarization techniques were used to investigate the inhibition efficiency of Basic Red 46. The copper sheets were cut into 1×1 cm pieces, polished carefully and immersed in 1M HCl solution for 30 minutes. Then, the EIS and polarization tests were carried out and the inhibition efficiencies were calculated.

Results: It was found that the Basic Red 46 to have good inhibiting properties for copper corrosion in acid, with efficiency between 83-88 % at a dye concentration of 400 ppm. The Langmuir adsorption isotherm could describe the dye adsorption on copper surface. Gibbs energy, ∆Gads, and equilibrium constants of inhibitor adsorption on copper surface were also calculated.

Conclusion: Since ∆Gads value obtained is very close to -40 kJ, it is possible to conclude that in addition to physical interactions, chemical effects may also exist. The nitrogen atoms of the molecule are suitable sites for interaction of dye with metal surface.