Assessment of pyrazole Schiff base's corrosion inhibition effectiveness incorporating oxadiazole moiety on mild steel in 1 M HCl: A holistic theoretical and experimental analysis

Abstract

Modern industries place a high value on reasonably priced, eco-friendly products that effectively stop metal breakdown. Hence, our goal was to create an ecologically acceptable pyrazole Schiff base (PSB) that would effectively preserve mild steel (MS) during pickling and descaling procedures. We achieved this by integrating oxadiazole, which demonstrated good anti-corrosion capabilities. A complete investigation was conducted using spectroscopic analysis, electrochemical techniques, and gravimetric measurement in 1 M HCl solution. The PSB inhibitor displayed considerable corrosion inhibition on MS. PSB exhibited both cathodic and anodic properties in its dual adsorption pattern, as shown by the electrochemical investigation. Polarization resistance (Rp) values rose with the PSB concentration from 50 to 300 ppm, peaking at 300 ppm with values ranging from 31.01 to 141.21 Ω.cm². At 300 ppm and 298 K, the inhibitor effectiveness reached 90.12 %. Electrochemical testing validated the protection against mixed-type corrosion, while surface examinations (SEM, EDS, CA, AFM) showed that PSB developed a protective antioxidant layer on the MS surface. According to theoretical DFT calculations, PSB adsorbs onto the steel surface in a flat alignment. The remarkable precision of the adsorption process was validated by the high coefficient of determination (R2 = 1) for both Langmuir and other adsorption isotherms. Computational, chemical, and electrochemical analyses all support PSB's superiority as a corrosion inhibitor. The incorporation of aryl and heterocyclic rings improves the PSB structure's molecular stiffness, which facilitates effective adsorption onto the MS surface. This feature creates novel prospects for material protection and corrosion prevention, presenting PSB as a viable and eco-friendly substitute for conventional corrosion inhibitors in industrial applications.