Inhibition of low carbon steel corrosion by a cationic gemini surfactant in 10wt.% H₂SO₄ and 15wt.% HCl under static condition and hydrodynamic flow

The corrosion inhibition potentials of a cationic gemini surfactant (CGS) on low carbon (LC) steel in highly corrosive environment of 10 wt.% H₂SO₄ and 15 wt.% HCl (which imitates oil well acidic environment) at elevated temperatures was studied using potentiodynamic polarization (PDP), gravimetric, and surface (XPS, SEM and EDX) analyses. Unprecedented inhibition efficiencies (IE) of 92.2% and 92.5% were repeatedly obtained at CGS concentrations of as low as 0.25 ppm and 1 ppm in 15 wt.% HCl and 10 wt.% H₂SO₄ at 25 °C by gravimetry, respectively. Higher inhibition efficiencies were obtained at elevated CGS concentrations. The inhibitor act as a mixed type based on the PDP data. The adsorption of CGS on the steel surface further supports a stronger tendency for he CGS adsorption onto the steel surface, thereby establishing an effective protective mechanism of the steel. The CGS performance was enhanced under hydrodynamic condition than static condition in 15 wt.% HCl while the opposite was the case in 10 wt.% H₂SO₄. Density Functional Theory (DFT) calculations and Monte-Carlo (MC) dynamics simulations supported the experimental findings of the CGS inhibition potentials for steel surface in the studied media. This study showcases the high potential of employing CGS for effective control of the corrosion, even at low dosage, in industrial applications involving the use of highly reactive acids at higher temperatures where economically viable operations are necessary.