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

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?, while it increases to 97.9% when 5 x 10(-4) mol L-1 of potassium iodide is added at 25?. 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.