Corrosion Inhibition of A 106 Gr B Carbon Steel by Thapsia Garganica Extracts in 1 M Hydrochloric Acid

The extracts of Thapsia garganica (Apiaceae) were used as green corrosion inhibitors to protect A 106 Gr B carbon steel against 1 M HCl solution. The inhibition effect of extracts methanolic (extract I) and ethyl acetate (extract II), were examined on carbon steel A 106 Gr B in hydrochloric acid with potentiodynamic polarization and electrochemical impedance spectroscopic technical. These measurements were made in an environment contains HCl alone and HCl plus the addition of different concentrations of the inhibitor (5; 10; 20; 30; 40 ppm), after 30 min of immersion, and taken at a temperature of (298±1) K. The inhibition efficiency of 96% was achieved with the addition of 40 ppm of me thanolic extract and 95% with ethyl acetate extract in 298 K. The extracts behaves are a mixed type corrosion inhibitors and is spontaneously adsorbed on the steel surface. Physisorption of two extracts is best described by the Langmuir adsorption model. Mechanism of inhibition was also investigated by calculating the thermodynamic and activation parameters like (ΔG), (Ea), (ΔHa) and (ΔSa). The originality of this work is the discovery of another safe, eco-friendly and non-toxic inhibitor from natural plants.