Wihania somnifera extract as a friendly corrosion inhibitor of carbon steel in HCl solution

• A.S. Fouda¹, A.M. Ahmed², S.M. El-Darier² and I.M. Ibrahim²

¹ Chemistry Department, Faculty of Science, El-Mansoura University, Mansoura, Egypt
² Chemistry Department, Faculty of Science, Alexandria University, Egypt

Abstract: There are many methods used to control the dissolution of metals. The use of inhibitors is one of such processes. Once chromates and some organic compounds were used as corrosion inhibitors. However, environmental scientists do not encourage this because chromates and those organic derivatives are toxic in nature. So, researchers are looking for environmentally friendly corrosion inhibitors such as extracts of plant materials. Several plant materials have been used for this purpose. Wihania somnifera (WSE) was studied as a friendly corrosion inhibitor against carbon steel corrosion in 1 M hydrochloric acid by mass reduction (MR), potentiodynamic polarization (PP), electrochemical frequency modulation (EFM) and electrochemical impedance spectroscopy (EIS) techniques. Surface analysis was performed on carbon steel with and without Wihania somnifera using an atomic force microscope (AFM). The impact of temperature was studied and explained. Investigation of experimental data denote that the inhibition efficiency (IE%) raises with raising concentration of Wihania somnifera extract while decreases with raising temperature. The activation and adsorption thermodynamic parameters such as ∆S*, ∆H* and E_a* were calculated and explained. The negative sign of ∆G₀ indicates that the process is spontaneous. Potentiodynamic polarization data identified that this Wihania somnifera extract acts as a mixed inhibitor and is physically adsorbed on carbon steel surface following the Langmuir adsorption isotherm. The charge transfer resistance increases, while the double layer capacitance decreases with an increase in Wihania somnifera extract concentration. The data from various techniques are in good agreement.

Keywords: corrosion inhibition, Wihania somnifera extract, carbon steel, HCl, EIS, mass reduction, potentiodynamic polarization

Int. J. Corros. Scale Inhib., 2021, 10, no. 1, 245-261 PDF (868 K)
doi: 10.17675/2305-6894-2021-10-1-14

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