Synthesis, experimental and computational studies on the anti-corrosion performance of substituted Schiff bases of 2-methoxybenzaldehyde for mild steel in HCl medium

Abstract

Corrosion inhibition performance of two synthesized Schiff base ligands; (E)-2-((2-methoxybenzylidene)amino)phenol L1 and (E)-2-((4-methoxybenzylidene)amino)phenol L2 were carried out by weight loss measurement in 0.1 M hydrochloric acid (HCl) solution. Density Functional Theory (DFT) and Molecular dynamics (MD) simulation were applied to theoretically explain the inhibitors’ intrinsic properties and adsorption mechanism in the corrosion study. The result of the inhibition performances carried out at varying concentrations and temperatures were compared. The corrosion inhibition efficiencies of L1 and L2 at an optimal concentration of 10 × 10–4 M were 75% and 76%. Langmuir isotherm model fits the data obtained from the experiment with a correlation coefficient (R2) value closer to unity. The adsorption mechanism of inhibitor on the surface of the Fe metal occurred via chemisorption inferred from the Gibbs free energy (ΔGads). Scanning electron microscopy showed a mild degradation on the surface of the mild steel immersed in the L1, and L2 inhibited acid solution, which could be due to surface coverage. The energy dispersive X-ray spectroscopy showed the metal surface’s elemental composition and the existence of the chlorine peak, which emanates from the HCl medium. DFT calculations revealed that the hybrid B3LYP functional performed better than the M06-2X meta-functional in estimating the energies of the synthesized Schiff bases for corrosion inhibition as seen in the lower ΔE values of 3.86 eV and 3.81 eV for L1 and L2. The MD simulation revealed that the orientation of inhibitors on the surface of the metal resulted in the coordination bond formation and that the interaction energy of L2 was −746.84 kJ/mol compared to −743.74 kJ/mol of L1. The DFT and MD results agreed with the observed trend of the experimental findings.

Exploring corrosion protection for mild steel in HCl solution: An experimental and theoretical analysis of an antipyrine derivative as an anticorrosion agent

“…Equation (10) defines the impedance of the CPE (Z CPE ) in the equivalent circuit, taking into account the CPE exponent (n) that reflects the inhomogeneity or roughness of the electrode surface.…”

“…Corrosive entities, such as H+ ions, relentlessly assail the metal's surface, fostering the formation of pits, cracks, and surface irregularities. [10][11][12][13] Notably, the corrosion of mild steel in HCl solutions can result in significant economic losses and pose safety hazards. [14] Industries including oil and gas, chemical processing, and metal fabrication frequently rely on hydrochloric acid for various applications, spanning from cleaning and acidizing to pickling.…”

“…[28][29][30] These inhibitors function by establishing a protective shield on the metal's surface, impeding corrosive agents and consequently retarding the corrosion rate. [31][32][33] Various classes of organic compounds, such as Schiff bases, pyridine derivatives, and benzotriazole derivatives, have been explored and demonstrated efficacy in corrosion inhibition. In light of this, this research article endeavors to delve into the inhibitory potential of HMBA as a corrosion inhibitor for mild steel in HCl solutions.…”

Coordinated metal complexes with curcumin Schiff base: Synthesis, investigation, antibacterial screening, antioxidant studies, molecular docking and density function theory calculations

“…It is sometimes referred by physicists as the bandgap between the conduction and valence energy bands. 24 Chemical hardness (η), a material's stability and reactivity are related. It was discovered that the energy gap of prepared Schiff base is 3.32 eV, and its Fe(III) complex is 2.37 eV, which showed a lower energy value than the free ligand indicating its successful preparation and coordination.…”

Experimental and Theoretical investigations of the Inhibition of the Corrosion of Mild Steel in HCl by Synthesized Piperazin Derivatives

“…A compromise towards adsorption will therefore be based on the creation of donor-acceptor pair based on the HOMO-LUMO interaction (Adinarayanan et al, 2022). This tendency is limited by the gap between the two orbitals (i.e the energy gap (E) as defined in Table . Consequently, a lower energy gap encourages ease of electronic transition from the HOMO to the LUMO and hence ease of adsorption (Ibeji et al, 2023). Such molecules with lower E are called soft molecules as opposed to hard molecules and are physically denoted by quantum parameters called softness and hardness (Eddy and Ita, 2011b).…”