N¹,N¹,N¹²,N¹²-Tetramethyl-N¹, N¹²-dioctyldodecane-1,12-diaminium bromide: Its synthesis and application in inhibition of mild steel corrosion in 15% HCl

A bis-quaternary ammonium bromide, N¹,N¹,N¹²,N¹²-tetramethyl-N¹,N¹²-dioctyldodecane-1,12-diaminium bromide (TDAB) was successfully synthesized and characterized with the elemental analyzer, FTIR, TGA, ¹H, and ¹³C NMR. Electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), potentiodynamic polarization (PDP), and weight-loss techniques were used to evaluate the corrosion inhibition performance of TDAB in a 15% HCl solution. TDAB showed an inhibition efficiency of ≈95% at 25 °C and an average of 90% at 45 °C and 60 °C at 311.17 µM. The thermodynamic parameters estimated values of ΔG⁰_mics, ΔG⁰_ads, ΔH^#_ads, and E_a was found to reveal typical behavior of physisorption of TDAB on mild steel, support unimolecular reaction, and obeyed Langmuir isotherm model. The ability of low concentration (15.56 µM) of TDAB to undergoes synergistic interaction with iodide ion was predicted (S_I = 1.92). SEM and XPS analysis confirmed the adsorption of the TDAB molecule on mild steel.