Ghars date extract/iodide ions system as an eco‐friendly corrosion inhibitor for <scp>API 5L X70</scp> steel in sulfuric acid

Abstract Background Ghars date fruit is very rich in polysaccharides, which qualifies it to be exploited as a green corrosion inhibitor. Ghars date is produced in large commercial quantities in Africa and Asia, which gives them the opportunity to be used as a cheap raw material for the industry of eco‐friendly inhibitors. Objectives The synergy between the Ghars date extract (GDE) and iodide ions is investigated for the first time to improve the inhibition efficiency for API 5 L X70 pipeline steel in 0.5 mol L −1 sulfuric acid. Methods The synergistic effect of the GDE and iodide ions is studied by potentiodynamic polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Results The inhibition efficiency is 45.5% at 2 g L −1 GDE at 20°C, while it increases to 97.9% when 5 × 10 −4 mol L −1 of potassium iodide is added at 25°C. The GDE/iodide ion system follows the Langmuir adsorption isotherm, involves both physical adsorption and chemical adsorption and acts as a mixed‐type inhibitor. Conclusions It is found that significant corrosion inhibition can be obtained in a synergistic manner between Ghars date extract and iodide ions for the API 5 L X70 pipeline steel in sulfuric acid.