Chemical and electrochemical corrosion of a copper alloy in aqueous solutions by using Morus Alba extract as an eco-friendly inhibitor

• A.S. Fouda¹, S.E. Badr², A.M. Ahmed² and A. El-Hossiany^1,3

¹ Chemistry Department, Faculty of Science, El-Mansoura University, Mansoura-35516, Egypt
² Chemistry Department, Faculty of Science, Alexandria University, Alex-21568, Egypt
³ Delta for Fertilizers and chemical industries, Talkha, Egypt

Abstract: Morus Alba extract was studied as the corrosion inhibitor for copper (Cu) in 2 molar HNO₃ utilizing chemical and electrochemical tests. From chemical tests, one can observe that with increasing doses of Morus Alba extract up to 300 ppm the inhibition efficacy was increased to 93.2% (after 3 hours) at 25°C. The adsorption of Morus Alba extract on Cu surface follows the Flory–Huggins adsorption isotherm. The inhibition efficacy increases with increasing the dose of the Morus Alba extract and decreases with rise in temperature of the medium. This extract may form a film which acts as a barrier, to minimize the contact area between copper surface and HNO3 solution. Morus Alba extract acts as mixed type of inhibitor in HNO₃ solution without any change in the mechanism of the process. From the EIS examination, we notice the decrease in the values of double layer by increasing the dose of Morus Alba extract, on the other hand, the charge transfer resistance is increased. Thermodynamic parameters of activation and adsorption processes were calculated and discussed that the sign of the free energy of adsorption showed spontaneous process of adsorption. The surface morphology of copper metal was examined by employing various techniques. Results are in good harmony for all techniques used.

Keywords: Morus Alba extract, corrosion inhibition, copper, nitric acid, Flory–Huggins isotherm, potentiodynamic polarization

Int. J. Corros. Scale Inhib., 2021, 10, no. 3, 1011-1029
doi: 10.17675/2305-6894-2021-10-3-12

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