Aspartic di-dodecyl ester hydrochloride acid and its ZnO-NPs derivative, as ingenious green corrosion defiance for carbon steel through theoretical and experimental access

Abstract

The ecological friendly and readily biodegradable amino acid based surfactant, aspartic di-dodecyl ester hydrochloride acid (ADH) and its ZnO-NPs derivative was synthesized and tested as corrosion inhibitor for metal in acidic medium. The synthesized surfactant was characterized by experimental and theoretical Fourier-transform infrared spectroscopy. The synthesis of ZnO-NPs with surfactant was confirmed by TEM/EDAX. The corrosion inhibition studies were performed using gravimetric analysis, potentiodynamic polarization and theoretical chemical calculations. The highest inhibition efficiency (%IE) was found to be 87.62% at 303.15 K with concentration 1000 ppm of ADH alone, while which raises to 92.59% with ADH-ZnO and was in close agreement as found by potentiodynamic results. Out of many adsorption isotherms, Langmuir was best fitted. The surface morphology were done by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX). Potentiodynamic polarization study confirms the type of inhibitor. Also the results of gravimetric analysis are in good agreement with that of potentiodynamic measurements. Inhibition mechanism was also investigated by calculating the thermodynamic and activation parameters like ΔG°, Ea, ΔH and ΔS. SEM pictographs show a different morphology in presence of ADH and showed the existence of an adsorbed protective film on the metal surface.