Experimental studies on the corrosion inhibition of API 5L Gr B steel by four bis-DABCOnium salts in sulfuric acid solution

Purpose This paper aims to examine corrosion inhibition of API 5L Gr B steel by four bis-DABCOnium salts in sulfuric acid solution (0.5M). This investigation was conducted at various concentrations of the studied inhibitors and experiment temperature (298–328°K). Design/methodology/approach The efficiency of these inhibitors was evaluated using gravimetric method, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Furthermore, atomic force microscopy and scanning electron microscopy were used to characterize the surface morphology. Findings The inhibition efficiencies determined by gravimetric are in good agreement with electrochemical measurements (EIS and polarization methods) and the corrosion inhibition efficiencies rise with the concentration of EtbDBr, PrbDBr, BubDBr and PebDBr and exceed 95% at 298°K at 5 × 10–3M. The tested compounds that were found to be a mixed type can be effectively used as corrosion inhibitors for steel in sulfuric acid and the efficiency dependent on the spacer chain size linked to nitrogen atoms. The adsorption on the metal surface matched the Langmuir adsorption isotherm and the inhibition efficiencies decreased with temperature. Originality/value The data of the present investigation reveal that DABCOnium salts are good inhibitors for steel in H2SO4 (0.5M) solution. The findings of this work shed more light on the corrosion inhibition of steel by ammonium salts in acidic medium