Abstract
The inhibitive effect and adsorption behavior of ginger roots extract (GRE) on the corrosion of carbon steel in 1.0 M HCl solution at different temperatures were investigated. The methods used were electrochemical studies (potentiodynamic polarization, electrochemical impedance spectroscopy, and electrochemical frequency modulation), chemical methods (weight loss measurements), surface analysis (atomic force microscopy [AFM]), and solution analysis (UV-visible spectrophotometric methods, such as Fourier transform infrared [FT-IR]). The analysis of the results showed that the inhibition efficiency increased with increasing the concentration of the inhibitor and decreased with temperature. The corrosion rate of carbon steel decreased in the presence of GRE. The corrosion inhibition efficiency increased with GRE concentration to attain 94% efficiency with 200 ppm at 25 °C. The thermodynamic activation parameters that govern the process were deduced from the temperature dependence. Potentiodynamic polarization curves indicated that the extract behaves as a mixed-type inhibitor. The extract was adsorbed on the carbon steel surface following the Langmuir adsorption isotherm. The adsorption free energy of GRE on carbon steel revealed a physical adsorption of GRE on the metal surface. The results from atomic force microscopy, Fourier transform infrared and UV-visible spectrophotometry analyses support the above inferences.