Abstract

ABDALLAH, M.; ABDEL-WANEESS, S.M.  and  ASSI, R.. Effect of Some Analytical Organic Indicators on the Corrosion of Nickel in Carbonate Solution. Port. Electrochim. Acta [online]. 2009, vol.27, n.2, pp.77-85. ISSN 0872-1904.

The effect of some analytical organic indicators, e.g. methyl red, methyl orange and methyl violet, on the corrosion of nickel electrode in 0.1 M K₂CO₃ was studied using galvanostatic and potentiodynamic anodic polarization techniques. The percentage inhibition efficiency was found to increase with increasing concentration of these compounds. The inhibitive action of these compounds is due to their adsorption on the nickel surface, making a barrier to mass and charge transfer, following Freundlich isotherm. The inhibition efficiency decreases in the order: methyl red > methyl orange > methyl violet. It was found that the addition of the chloride, bromide, iodide and thiosulfate ions accelerates the pitting corrosion of nickel in 0.1 M K₂CO₃ solutions by shifting the pitting potential to more negative direction. The addition of these analytical organic compounds protects the nickel against pitting corrosion in bromide containing solution.

Keywords : methyl red; methyl orange; methyl violet; nickel; corrosion inhibitors; pitting corrosion.

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