Effect of vegetal tannin on anodic copper dissolution in chloride solutions

The corrosion inhibition of copper in a 0.1 M NaCl solution in the presence of vegetal tannin using potentiodynamic techniques was studied. The tannin was extracted from Takaout galls ( Tamarix articulata ). The gallic acid has been used as a representative of the tannin species. The tannin are anodic inhibitors. The inhibition efficiency of the tannin evaluated from anodic polarization curves and impedance measurements is about 93.2% for a tannin concentration of 2 g/l. We noted that the presence of tannin changes the mechanism of copper dissolution in a 0.1 M NaCl solution. Microscopic scanning studies of the surface state revealed the formation of corrosion layer products. The impedance investigation allows the explanation of the inhibition process. © 2003 Elsevier Ltd. All rights reserved.