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Anodic polarisation behaviour of copper in chloride and bromide solutions containing benzotriazole, tolyltriazole, and methylbenzimidazole Aben, Terence John


The interactions of oxide free copper surfaces with the organic chemicals benzotriazole, tolyltriazole and methylbenzimidazole were studied in solutions containing sodium chloride to elucidate the effect of modifying the molecular structure of benzotriazole on the inhibition of copper corrosion. All experiments were performed in solutions containing 1M NaCl. Experiments were performed using organic molecule concentrations of 8.39 x 10⁻³ M and 8.39 x 10⁻⁴ M and at pH values of 6.0 and 3.0. Potentiodynamic polarisation studies were used to gather information that was then compared to the established potential-pH equilibria. Polarisation scan rates of 1 mV/s and 0.2 mV/s were used. Inhibition of the anodic dissolution reactions was observed under all conditions studied using benzotriazole and tolyltriazole. The inhibition behaviour of benzotriazole and tolyltriazole are very similar and appear to use the same inhibition mechanism. Methylbenzimidazole was not found to produce an inhibiting effect. The potential-pH (E-pH) diagram for the Cu-Br⁻-H₂0 system was constructed from the available thermodynamic data. Polarisation scans were performed using copper in bromide solutions at pH 3.0 and 6.54 to confirm the behavioural redictions based on the E-pH diagram. To confirm the inhibition model proposed by Tromans et al.¹ on the behaviour of benzotriazole on oxide free copper surfaces in chloride media, experiments were performed in solution containing bromide and benzotriazole to eliminate the possibility of synergistic reactions with chloride, as well as to collaborate previous conclusions with a different set of thermodynamic data. Potentiodynamic polarisation studies were used to gather information on the behaviour of benzotriazole and tolyltriazole in sodium bromide solutions at pH values of 3.0 and 6.0.

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