Journal of Molecular Liquids
J. Mol. Liq. 273 (2019) 476-487
A novel palmitic imidazoline compound, N-(2-(2-pentadecyl-4,5-dihydro-1H-imidazol-1-yl)ethyl)palmitamide (NIMP) has been successfully synthesized and characterized with Fourier transform spectroscopy (FTIR), Proton nuclear magnetic resonance (1H NMR), and Carbon-13 nuclear magnetic resonance (13C NMR). NIMP has been tested as corrosion inhibitor for N80 steel in 15% HCl solution at low and elevated temperatures using weight loss measurements, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), linear polarization (LPR), and electrochemical frequency modulation (EFM) techniques. The experimental investigation was supported with surface examination using scanning electronmicroscope (SEM), energy dispersive X-ray spectroscopy (EDAX), and Fourier transform spectroscopy (FTIR). NIMP is found to be effective in retarding N80 steel dissolution in 15% HCl solution at studied temperatures. The optimum concentration of NIMP is 300 ppm and this concentration afforded corrosion protection efficiency of 97.92% and 95.59% at 25 °C and 60 °C respectively from weight loss measurements. Chemisorption is proposed as the mechanism of adsorption of NIMP molecules onto N80 steel surface based on the value of standard enthalpy of adsorption (100.34 kJ/mol). PDP results disclosed that NIMP acted like a mixed type corrosion inhibitor but with principal effect on cathodic corrosion reactions. Surface screening results are in agreement with experimental results that NIMP molecules adsorbed on N80 steel surface. NIMP can be utilized as an acidizing corrosion inhibitor.