Corrosion inhibition characteristics of a novel salycilidene isatin hydrazine sodium sulfonate on carbon steel in HCl and a synergistic nickel ions additive: A combined experimental and theoretical perspective

Salycilidene isatin hydrazine sodium sulfonate (SHMB) is synthesized and characterized by different spectroscopic tools. The inhibition performance of the individual SHMB, and that in a combination with various [Ni-2(+)] ions on the carbon steel (CS) corrosion in hydrochloric acid are investigated, using electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) corrosion rate and potentiodynamic polarization (PDP) methods. The SHMB inhibits the corrosion of CS in 1.0 M HCl up to 87.8%. The synergism of this SHMB Schiff base and Ni2+ is confirmed from the findings. Combining the SHMB with nickel ions increases the inhibition capacity of up to 99.2%. PDP studies indicate that the individual SHMB and SHMB + nickel cations systems can act as inhibitors of the mixed-type. The best fitted Langmuir isotherm model reveals that the adsorption process occurs through both physical and chemical adsorption in the case of individual SHMB and chemisorption in the presence of a mixed system. X-ray diffraction, UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Field-emission scanning electron microscope/energy-dispersive X-ray spectroscopy (FE-SEM/EDX) are utilized to study the surface morphology and corrosion product phases of CS specimens. The findings of density functional theory (DFT) calculations and molecular dynamic (MD) simulations suggest high adsorption feasibility of molecular and protonated SHMB.