A study of the anti-corrosive effects of essential oils of rosemary and myrtle for copper corrosion in chloride media

Abstract

The objective of this research work is the study of the essential oils (EOs) of myrtle (MEO) and rosemary (REO) as novel and eco-friendly corrosion inhibitors. These EOs were extracted by the Clevenger technique and analyzed using the Gas Chromatography/Mass Spectrometry (GC/MS) and Fourier-transform infrared spectroscopy (FTIR). These techniques show that MEO and REO were rich in various volatile compounds. The investigation of copper corrosion behavior in 3 wt% NaCl solution, in the presence of EOs, via open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) was carried out. The results of the electrochemical tests presented the same trends: EOs acting as cathodic type inhibitor for copper in 3 wt% NaCl solutions, the inhibition efficiency increasing upon the addition of EOs and the further increase with the increase of the EOs concentration and REO having moderately superior performance compared to MEO. The EOs molecules adsorption on the copper surface followed a Langmuir isotherm, and physical adsorption (vs. chemical adsorption) is dominant.