Corrosion inhibition of mild steel by highly stable polydentate schiff base derived from 1,3- propanediamine in aqueous acidic solution |
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| Institution: | 1. Department of Chemistry, College of Science, Jouf University, PO Box 2014, Sakaka, Saudi Arabia;2. Air Pollution Research Department, Environmental and Climate Change Research Institute, National Research Centre, Dokki, Giza 12622, Egypt;3. Laboratory of Electrochemistry, Molecular Engineering and Redox Catalysis, Department of Process Engineering, Faculty of Technology, University of Ferhat Abbas, Setif 19000, Algria;4. Department of Chemistry, College of Science and Arts, Jouf University, Saudi Arabia;5. Department of Chemistry, Faculty of Science, Islamic University of Madinah, PO Box 42351, Al-Madinah Al-Munawwarah, Saudi Arabia |
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| Abstract: | Recently, the hydrolysis of Schiff bases under experimental conditions gives suspicion for their corrosion inhibition performance. The current study employs a stable Schiff base namely, 2,2′-{propane-1,3-diylbisazanylylidene (E) methanylylidene]}bis(6-methoxyphenol) (LPD) as corrosion inhibitor for mild steel (MS) in 1 M HCl solution. The presence of the characteristic peak of the imine group in UV-visible spectra was taken as an indicator for LPD stability in acidic media. The inhibition action was examined using electrochemical techniques including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) besides gravimetric measurement. The inhibition efficiency reached 95.93 % for 0.75 mM LPD after 24 h of immersion at 25 °C. This high efficiency is owing to the presence of the characteristic imine group and other heteroatoms and π- electrons of the aromatic benzene rings. The mechanism of inhibition depends on adsorption phenomena on mild steel surface which obeys Langmuir isotherm model. The calculated values of adsorption equilibrium constant (Kads), adsorption free energy ΔGads, adsorption enthalpy ΔHads and adsorption entropy ΔSads indicated spontaneous exothermic adsorption process of both physical and chemical nature. By rising temperature, the inhibition efficiency of LPD was decreased. The calculated activation energy was increased as the concentration of LPD increased. LPD was considered as a mixed-type inhibitor as indicated from PDP measurements. The obtained surface morphology and composition analysis using SEM/EDS, AFM and FTIR techniques ensures the high efficiency of LPD as corrosion inhibitor. |
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| Keywords: | Schiff base Corrosion inhibitor Mild steel SEM/EDX FTIR AFM Adsorption isotherm |
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