High-performance green corrosion inhibitor for P11 steel in 1 M HCl with synergistic enhancement by KI

In this investigation, the corrosion inhibition capacity of linseed gum (LSG), a green biopolymer, was assessed for P11 steel in 1 M HCl, both individually and in conjunction with potassium iodide (KI), within a temperature range of 25-65C.Gravimetric and electrochemical techniques, as well as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS), were implemented to analyze the inhibition mechanism and surface interactions.As a mixed-type inhibitor with mostly anodic control, LSG demonstrated considerable inhibitory efficiency, reaching up to 90% at 65C.Thermodynamic investigations indicated a spontaneous and endothermic process including both physisorption and chemisorption mechanisms, and adsorption followed the Langmuir isotherm.The addition of 5 mM KI to the acidic solution containing 1 gL -1 of LSG improves the performance, reaching a maximum inhibitory efficiency of 96.5% at 65C.The synergism parameters (S < 1) indicated that the adsorption mechanism was competitive rather than cooperative.The formation of a protective film on the steel surface was corroborated by electrochemical impedance spectroscopy and SEM/EDS results, which effectively mitigates corrosion damage.These findings emphasize the potential of LSG as an eco-friendly, effective corrosion inhibitor for P11 steel in acidic environments, particularly when combined with KI.