Proficient Schiff’s Bases as Facile Structures to Limit Corrosion of Mild Steel: Synthesis and Electrochemical Studies Aided by Computational Quantum Parameters

The inhibition capabilities of two afresh synthesized Schiff bases (SBs), i.e. 2,2'-((((1,4-phenylene bis(azanediyl))bis(4,1-phenylene))bis(azanylylidene))bis(methanylylidene)) diphenol (SB-I) and 3,3'-((((1,4-phenylenebis(azanediyl))bis(4,1-phenylene))bis(azanylylidene))bis(methanylylidene))diphenol (SB-II) were used as corrosion inhibitors for mild steel(MS) in 0.5 M H₂SO₄ medium. Corrosion controlling the tendency of SB-I and SB-II was calculated by weight loss, electrochemical impedance spectroscopy (EIS) and Tafel polarization methods. The highest inhibition efficiencies observed were 97.04% (SB-I) and 95.21% (SB-II) with higher inhibitors concentration (200 mg L⁻¹) at 298 K temperature. The studied SBs depict that the inhibition efficiency was increased with increasing the inhibitor concentrations but showed a fall with rising temperatures. Tafel polarization indicates that the SBs acted as mixed-type candidates. EIS confirms that the value of charge transfer resistance (R_ct) increases at higher concentrations of each SB which proposed that adsorption by inhibitors on a mild steel surface. The Langmuir adsorption isotherm follows adsorption. The anticorrosive layer formed by the inhibitors molecule due to the adsorption on the mild steel surface is supported by Scanning electron microscopy (SEM), Atomic force microscopy (AFM) and attenuated total reflectance (ATR) studies. Computational data were analyzed using density functional theory (DFT) with Fukui functions and molecular dynamics (MD) that are in good relationship with the experimental outcomes.