Avaliação anticorrosiva do aço carbono ABNT 1020 por Lycium Barbarum

Abstract

Carbon steel is an alloy widely used industrially, but it is susceptible to corrosive processes that degrade the metallic surface and cause financial losses and environmental damage. One of the ways to avoid corrosion is the use of inhibitors, which act by adsorption on the metal surface. Traditional inhibitors are toxic and come from a non-renewable source, so natural products are tested as possible substitutes for toxic inhibitors. This thesis aims to evaluate the inhibitory effect of Lycium barbarum fruit (Goji Berry) against the resistance of carbon steel ABNT 1020 in NaCl and H2SO4 both at 0.5 mol L-1. Electrochemical techniques of Open Circuit Potential, Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy and gravimetric assays were used; the metallic surface was conducted by Scanning Electron Microscopy and the extracts were characterized by Fourier Transform Infrared Spectroscopy and Gas Chromatography with coupled mass spectrometry. The surprising results that the Goji Berry has an anticorrosive effect on the studied electrolytes, in the electrochemical and mass loss tests, it was possible to obtain an inhibitory efficiency of up to 98% in the presence of the extracts. The variation electron micrographs show that in the presence of Goji Berry the texture type is changed from localized to generalized. The FTIR and GC-MS results prove that the compounds from Goji Berry have heteroatoms such as O, S and N that promote adsorption on the metal surface, in addition to the presence of alcohols, esters, carboxylics and polyphenols.