Corrosion resistance of mild steel under acidic conditions using iodine nitrotetrazolium violet: Experimental and theoretical research

Iodine nitrotetrazolium violet (INT) is commonly used in the fields of biology and medicine. Nitrogen-containing heterocycles typically exhibit good corrosion inhibition effects. Therefore, INT exhibits potential as a corrosion inhibitor in the realm of corrosion control. The applicability of tetrazolium derivatives INT in the area of anti-corrosion was explored through experimental investigations and computational analyses. In this research, electrochemistry technique was applied to investigate the corrosion prevention impact of INT on mild steel in 1 M HCl. Electrochemical testing indicated that the inhibitor INT with a concentration of 0.4 mM had the best corrosion inhibition effect at room temperature of 298.15 K, with an efficiency of up to 98.38 %. In addition, the effect of the addition of KI or KCl on the corrosion inhibition properties was also investigated. Adsorption curves were used to describe the adsorption behaviour and INT was found to conform to the Langmuir adsorption isotherm. Scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), contact angle (CA) and X-ray photoelectron spectroscopy (XPS) provided additional evidence of the protective effect of INT on the metal substrate. Molecular dynamics simulations and quantum chemical calculations were carried out to gain insight into the adsorption mechanism. It was found that INT molecules covered the surface of mild steel to the maximum extent through parallel adsorption and form π complexes with the MS surface. Overall, there is consistency between the experimental and theoretical findings, revealing that INT has a notable inhibitory effect on corrosion.