The corrosion inhibition efficiency of carbon steel in HCl solution utilizing pistachio soft hull extract: Experimental measurements, DFT and MD simulations

Abstract

• Pistachio soft hull extract which contained phenolic structure incresed the steel corrosion resistance in 1 M HCl solution. • Due to PDP results, the inhibition efficiency rose to 87 % at 400 ppm. • The experimental test plud the limited DFT and MD simulation was done for the adsorption of PSH extract. • The effectiveness of the inhibitor decreased to the range of 10–30 % over the 168-hour period. In this paper, the effect of pistachio soft hull (PSH) extract, containing phenolic, flavonoid, proanthocyanidin, and tannin, on the corrosion resistance property of carbon steel (st 37) in 1 M HCl solution at various concentrations was figured out. Weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization (PDP), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and theoretical calculations on two predominant molecules were conducted. Theoretical methods included chemical quantum calculations and molecular dynamics simulations. The maximum inhibition efficiency recorded was 87 % for a concentration of 400 ppm of PSH extract in 1 M HCl at 298 K. The PDP analysis revealed that the PSH extract functioned as a mixed-type inhibitor via a physical mechanism, as evidenced by a Δ G° ad value of approximately –16 kJ mol -1 . Quantum calculations demonstrated that gallic acid's oxygen atoms in the hydroxyl group showed the highest nucleophilic behavior, as they were attached to the cyclic carbon group.