Adsorption and Corrosion Inhibition Properties of Butanolic Extract of Elaeoselinum thapsioides and Its Synergistic Effect with Reutera lutea (Desf.) Maires (Apiaceae) on A283 carbon Steel in Hydrochloric Acid Solution

The current investigation presents the corrosion activity of Elaeoselinum thapsioides (BEET) butanolic extract in 1 M HCl as a novel green source of corrosion inhibitor, and it's synergetic effect with another butanolic extract of Reutera lutea (BERL), whose belongs to the Apiaceae family. Weight loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements have been done to study the inhibition efficiency. The obtained results showed that the inhibition efficiency of BEET alone increase with concentration and reached a value of 82% at 900 ppm. However, the maximum protection efficiency was more than 92% with the combination of BEET and BERL inhibitors. The rise of temperature caused a significantly decreased of inhibition efficiency. The potentiodynamic polarization results revealed that the extract functions as mixed-type inhibitor with predominance at anodic domain, and the adsorption process of the extract follows Langmuir isotherm. In addition, EIS shows that increasing the concentration of the inhibitor leads to an increase of the charge transfer resistance and reducing the double layer capacitance. The synergistic factor (S) was used to investigate the synergistic behavior of the selected inhibitors.