Avaliação do desempenho de toliltriazol como inibidor de corrosão para o cobre em meio aquoso ácido

Abstract

Corrosion is a natural process that causes the degradation of metallic materials, resulting in significant economic losses in several industries. To mitigate this problem, inhibitors have been widely studied and used as a strategy to increase the protection of these materials. Among the inhibitors used for this purpose, tolyltriazole (TTAH) stands out, which is an organic compound belonging to the class of triazoles, and which has aroused interest due to its versatile properties, its potential for various industrial applications and its low toxicity. In this context, this work aimed to evaluate the efficiency of a commercial corrosion inhibitor based on TTAH against a copper substrate in 0.1 M HCl medium. Initially, the copper substrate was characterized using several techniques, including metallography, microhardness determination, glow-discharge optical emission spectroscopy (GD-OES), field emission scanning electron microscopy (FEG-SEM) and energy dispersion spectroscopy (EDS). Then, the substrate was exposed to the corrosive medium in the absence (0 ppm) and in the presence of the commercial corrosion inhibitor, using different concentrations of TTAH (5, 10 and 20 ppm), with the objective of evaluating the corrosion rates. The monitoring of the corrosive process was carried out by means of mass loss tests and also by measurements of open circuit potential as a function of time, polarization curves and electrochemical impedance spectroscopy. In general, the characterization results showed a pure commercial copper substrate, with denominations between UNS C10100 and C13000. Regarding the mass loss tests, it was observed generalized corrosion as well as a reduction in corrosion rates in the presence of TTAH, with inhibitory indices of 62.82 and 76.02% for concentrations of 5 and 10 ppm of TTAH, respectively. There was no apparent detection of mass loss in the electrolyte containing 20 ppm of TTAH, although substrates immersed in this condition showed localized corrosion. The electrochemical tests, in turn, revealed that TTAH behaves as a predominantly anodic inhibitor in all media studied. The polarization curves showed that in the Tafel region, the inhibitor film in TTAH medium obeys the Langmuir adsorption isotherm. The results obtained through this technique point to an inhibition effectiveness of 81.3 to 96.1%. Moreover, tests by MEV-FEG, followed by EDS, indicated the presence of nitrogen on the surface of the cooper substrate, ensuring the formation of a protective monolayer. Finally, the results obtained in this work demonstrated that the commercial product, formulated with TTAH, is promising and has a high potential in protecting copper under conditions that are similar to those applied in the tests carried out. It is hoped that this study will contribute to the advancement of scientific knowledge and stimulate the development of new technologies and products based on TTAH. [resumo fornecido pelo autor]