Althaea officinalis extract as a sustainable and green inhibitor for protection of carbon steel in 0.5 M HCl

This study aimed to investigate the use of Althaea Officinalis extract (AOE) as a corrosion inhibitor for carbon steel (CS) in 0.5 M HCl solution. The AOE was extracted using heat-assisted extraction (HAE) and microwavesassisted extraction (MAE) methods. The effectiveness of the AOE as an inhibitor was evaluated using weight loss measurements, electrochemical impedance spectroscopy (EIS), and Tafel polarization techniques. The adsorption behavior of the AOE on the CS surface was analyzed through adsorption isotherms. Additionally, the impact of temperature on the inhibition efficiency (IE%) and polarization behavior of the AOE extracted through both methods was studied. Thermodynamic parameters were calculated for the CS in 0.5 M HCl with and without the AOE. The results showed that the AOE extracted through the MAE method at a concentration of 800 ppm achieved a maximum IE% of 92.82%. Scanning electron microscopy (SEM) analysis confirmed the protective effects of the AOE on the CS surface in the 0.5 M HCl solution.