Corrosion inhibition and surface examination of carbon steel 1018 via N-(2-(2-hydroxyethoxy)ethyl)-N,N-dimethyloctan-1-aminium bromide in 1.0 M HCl

Hydroxy-ethoxy N-(2-(2-hydroxyethoxy)ethyl)-N,N-dimethyloctan-1-aminium bromide (HEDOB) cationic surfactant had been prepared and investigated as a steel protector against its corrosion in 1.0 M HCl. Different techniques such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, electrochemical frequency modulation (EFM) and weight loss techniques were conducted for investigating the corrosion inhibition efficiency of the HEDOB inhibitor at four different temperatures (25-55 °C). The corrosion inhibition of hydroxy-ethoxy HEDOB surfactant inhibitor is dependent on both its effective concentration and solution temperatures as clarified via weight loss results with maximum inhibition efficiency 88.9% at 1000 μM and 55°C. Langmuir's adsorption isotherm was confined as best fitted isotherm describes the physical-chemical adsorption capability of the HEDOB on the steel surface with change in the free energy of adsorption from -38.8 to -43.6 kJ/mol. The provided Tafel polarization results revealed that the hydroxy-ethoxy HEDOB surfactant promote the suppression both the cathodic and anodic reactions behaving as mixed-type inhibitor. The surface morphology techniques SEM and AFM revealed that, the HEDOB inhibitor is confined on the surface of the steel. The Quantum theoretical study revealed the correlation between the hydroxy-ethoxy HEDOB molecular chemical structure and its inhibition efficiency.