Optimization, molecular dynamics and quantum parameters simulations of Zingiber officinale rhizome as a green corrosion inhibitor

Abstract

This study combines experimental and theoretical approaches to investigate ginger root extract (GRE) as an eco-friendly corrosion inhibitor for mild steel in acidic environments at temperatures ranging from 303 to 333 K. Experimental techniques, including weight loss measurements, were used to assess the inhibiting performance and adsorption behavior of GRE, while GC-MS, FT-IR, and UV-visible spectrophotometric methods provided further characterization. Results indicated that the inhibition efficiency of GRE increased with higher concentrations and decreased with temperature, highlighting its potential to effectively prevent corrosion in H₂SO₄ medium. GC-MS analysis identified four major phenolic compounds-6-gingerol, 6-isoshogaol, zingerone, and vanillyl glycol-and two secondary metabolites, α-Farnesene and β-Bisabolene. Among these, 6-gingerol, the most active and abundant constituent, was selected for computational studies. Optimal corrosion inhibition of 81.3 % was achieved at 303 K with a GRE concentration of 10 g/L for 1 h. Thermodynamic activation parameters suggested a temperature-dependent process, and alignment with the Langmuir isotherm indicated a physical adsorption mechanism. Quantum chemical calculations for 6-gingerol revealed highest occupied molecular orbital energy (E_HOMO) and lowest unoccupied molecular orbital energy (E_LUMO) values of -6.286 eV and -0.366 eV, respectively, in its protonated state, and -8.338 eV and -0.247 eV, respectively, in its neutral state. Molecular simulations showed a binding affinity of -4.736 kJ/mol between 6-gingerol and the steel surface, supporting the experimental findings and underscoring the potential of GRE as an effective corrosion inhibitor.

Keywords: Corrosion inhibition; Mild steel; Molecular dynamic; Quantum chemical calculation; Zingiber officinale rhizome.

Fig. 1

GC-MS chromatogram of ginger extract.

Fig. 2

Mass spectrograms of GRE (a: 6-Gingerol; b: 6-Isoshogaol; c: Zingerone; d: Vanylglycol; e: ∝- Farnesene; f: β-Bisabolene).

Fig. 3

Variation of (a–c) CR and (d–e) IE (%) of GRE with inhibitor concentration in 5M H₂SO₄ at various temperatures and immersion times.

Fig. 4

Arrhenius plot for mild steel corrosion study in 5 M H₂SO₄ solution with and without GRE.

Fig. 5

Transition state plots for mild steel corrosion study in 5 M H₂SO₄ solution with and without GRE.

Fig. 6

FT-IR spectra of the extract of pure GRE and the GRE extract with corrodent.

Fig. 7

UV–visible spectra of GRE before and after 3 h of immersion of mild steel.

Fig. 8

The HOMO and LUMO orbital visualization of the neutral and the protonated GRE.

Fig. 9

Molecular electrostatic potential of the GRE, in neutral and protonated states.

Fig. 10

The equilibrium adsorption configuration of Side and top view for the neutral and protonated inhibitor species on the Fe (110) surface at temperature of 303 K and 333 K.

Fig. 11

Schematic depiction of corrosion mechanism portraying the mode of adsorption of molecules of ginger onto the MS substrate.