Estudo do extrato de Anacardium Occidentale como inibidor verde de corrosão

Abstract

The extract of Anacardium Occidentale was evaluated as a possible green corrosion inhibitor for steel low carbon in NaCl 3,5% solution. For this, potentiodynamic polarization, electrochemical, impedance spectroscopy (EIS), contact angle measurements, scanning electron microscopy (SEM) were performed. The polarization curves show that the presence of the extract causes a significant change in the Ecorr, which varies from -498 to -687 mV, classifying the cashew leaf extract as a cathode inhibitor. The electrochemical impedance, in turn, showed a small increase in Rp and a reduction in the capacitance of the electric double layer, indicating that the molecules present in the extract absorb and form a complex with the iron ions on the metal surface. The contact angle measurements revealed the formation of a hydrophobic protective film who was defined by immersion in NaCl 3,5% solution in absence and presence of inhibitor showed angles of 24 º and 64 º respectively. The SEM indicates that the film formed after three days of immersion was more homogeneous and compact, this ensure a better protection for the material. The gravimetric analysis revealed that the efficiency of the extract as a corrosion inhibitor is greater after 3 days immersed, reaching values higher than 40%.