Avaliação de rejeitos de Paullinia cupana como inibidor de corrosão em aço carbono aplicando técnica gravimétrica e de ruído eletroquímico

Abstract

In order to reduce or avoid corrosion, it is necessary to pursue methods that are economically, technologically and environmentally viable. Thus, the corrosion inhibitors based on organic compounds appear as a promising alternative because they are renewable, biodegradable, low cost and don’t contain heavy metals. In this context, with the intention of evaluating Paullinia Cupana (guaraná) leaves as anticorrosive inhibitor, test specimens were submitted to weigth loss and electrochemical noise tests. In the weigth loss test, with acidic medium, 1.0 M HCl and 0.5 M H2SO4. It was observed that the efficiency of the inhibitor increases as its concentration increased. In order to evaluate the influencing factors in the corrosion process, it was used Design of Experiments, Taguchi Method. With this method it was observed that the acid medium, HCl and H2SO4, the temperature and presence of inhibitor are the factors that most affect corrosion process, besides the test time and type of steel. In addition, this study indicated that there is no interaction between the factors analyzed. The study of corrosion by electrochemical noise technique has shown that this inhibitor is efficient because it reduces a current noise intensity, increasing a corrosion resistance, as observed through RN. It was also observed that the guarana leaves inhibitor acts more effectively in the HCl medium, which was proved by the use of the FTIR technique that some organic compounds responsible for inhibition are oxidized in the H2SO4 medium, being that indicates inhibitor for corrosion In HCl medium.