Probing inhibition effect of novel biopolymer based composite for the inhibition of P110 steel corrosion in 15% HCl under dynamic condition

The present work shows the chitosan composite development using Salicylaldehyde (Sali-Cht). The developed composite was used as P110 steel corrosion inhibitor in 15% HCl under dynamic condition at 1500 rpm using electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), and potentiodynamic polarization (PDP). The EIS results disclosed that Sali-Cht inhibits corrosion via charge transfer process. The PDP data indicated that Sali-Cht suppresses both the cathodic and anodic corrosion process. The maximum inhibition efficiency of Sali-Cht is 89.23% (400 mg/L). The adsorption of Sali-Cht over the steel surface was confirmed using X-ray photoelectron spectroscopy (XPS). Morphological changes on the steel surface were monitored by scanning electron microscopy (SEM). The thermodynamic parameters such as the adsorption equilibrium constant (K_ads) and the free energy of adsorption (ΔG_ads) were calculated and discussed. Several adsorption isotherms were tested and the experimental data fitted well with the Langmuir adsorption isotherm. Density functional theory (DFT) suggests that protonated forms of Sali-Cht have more adsorption ability than neutral forms. Molecular dynamic simulation (MD) study revealed that protonated form adsorbed flatly over the P110 steel surface, while neutral form adsorbed in a twisted manner.