1,12-Dodecyldiyl-bis(dimethylalkylammonium bromide) compounds anticorrosion property on C1018/15% HCl solution interface: Experimental, molecular dynamics simulation, and DFT studies

The experimental, molecular dynamics (MD) simulation, and density functional theory (DFT) study approach were used to investigate the comparative anticorrosion performance of 1,12-Dodecyldiyl-bis(dimethyloctylammonium bromide);TDAB C-8, 1,12-Dodecyldiyl-bis(dimethyldodecylammoniumbromide);TDAB C-12, and 1,12-Dodecyldiyl-bis(dimethylhexadecylammoniumbromide); TDAB C-16 on C1018 mild steel in 15% HCl solution. The mixed-type corrosion inhibition mechanism of TDAB inhibitors was revealed by the potentiodynamic measurements and obeyed Langmuir adsorption isotherm model at 25 °C. The corrosion inhibition efficiencies of 98.90%, 98.29%, and 97.09% were achieved with 200 mg L⁻¹ TDAB C-8, 10 mg L⁻¹ TDAB C-12, and 15 mg L⁻¹ TDAB C-16 respectively, translating to order of efficacy to be TDAB C-12 ˃ TDAB C-16 ˃ TDAB C-8 at 25 °C. The orientations of TDAB's inhibitors on Fe (1 1 0) surface as revealed by the MD simulation, the DFT chemical descriptors such as the HOMO-LUMO gap energy (ΔE), the dipole moments of 11.712, 18.284, and 18.134 debyes, respectively for TDAB C-8, TDAB C-12, and TDAB C-16 and their tendency to promote back-donation of electrons from the d-orbital of the iron (Fe) of the C1018 mild steel owing to their high electrophilicity index (ω) are responsible for the difference in the performance of TDAB inhibitors. The existence of predominantly physisorption processes of TDAB inhibitors on C1018 mild steel was confirmed by the effect of temperature on the corrosion inhibition efficiencies of TDAB inhibitors. The activation energy (E_a) and the enthalpy of adsorption (ΔH_ads) energy support the unimolecular reaction process of TDAB inhibitors on C1018 mild steel.