Sistemas microemulsionados a base de Anonna muricata (Anonnaceae) como inibidores de corrosão em aço AISI 4142

Abstract

The development of techniques that minimizes the effects caused by the corrosive processes, associated with the cost benefit of ecologically viable alternatives, is replaced by more relevant to society. The objective of this work was to prepare microemulsion systems (SME) as steel corrosion inhibitors AISI 4142 from the oil of Annona muricata (Annonaceae) (Am) (Soursop), and NaCl in an aqueous solution with a concentration of 3.5%, as aqueous phase, simulating the corrosive medium. In order to stabilize the system Tween 80 was used as surfactant (T) and ethanol as a cosurfactant (TOC). The rheological properties were evaluated, the structure and the potential inhibition were analyzed by small angle X-ray scattering and electrochemical tests, respectively. Rheological measurements showed that all systems showed typical Newtonian behavior of SME and confirmed by SAXS. From application models, the results demonstrate that the microemulsions showed ellipsoidal shape "core-shell" for all SME except for samples with 70% aqueous phase, 27% oil phase and 3% surfactant which showed structures elongated cylindrical. Electrochemical tests polarization by extrapolation of Tafel plots were performed and demonstrate that all EMS had good corrosion resistance. The efficiency obtained for the samples show a percentage inhibition of 14.7% ME1, ME2 14.7%, 13.4% ME3, ME4 12.2% and 10.7% for ME5, and also evidenced an offset the most positive potential compared with curves for the solution without microemulsion. The results showed that obtained from EMS of Annona muricata (Annonaceae) oil are potential corrosion inhibitors, ME2 and 14.7% inhibition and a bend located at higher current density values, the sample showing be best inhibitor.