Adsorption and Inhibition Analysis of Aconitine and Tubocurarine Alkaloids as Eco-friendly Inhibitors of Pitting Corrosion in ASTM – A47 Low Carbon Steel in HCl Acid Environment

The research on the adsorption and inhibition analysis of aconitine alkaloid (ACA) and tubocurarine alkaloid (TBA) as eco-friendly inhibitors of pitting corrosion in ASTM – A47 low carbon steel in HCl acid was carried out under the following experimental and analytical methods: gravimetric method, gasometric method, electrochemical impedance spectroscopy, potentiodynamic polarization, and scanning electron microscopy method. Results revealed good inhibitors as inhibition efficiencies were recorded at 98.8% and 91.2% at a maximum inhibitor concentration of 1500 ppm for tubocurarine and aconitine alkaloids, respectively. The inhibition efficiency was found to increase with increasing inhibitor concentrations indicating a strong binding between inhibitor molecules and ASTM – A47 low carbon steel in HCl acid. Electrochemical data strongly supported the efficacy of both inhibitors as earlier presented by the chemical methods as a trend in values of charge transfer resistance, double layer capacitance, corrosion potential, and corrosion current density were in accordance with standards for a good inhibitor. The inhibitors were seen to be spontaneous, stabled, endothermic and physically adsorbed. Adsorption of the inhibitors on metal surface obeyed Langmuir, El-Awady, Freundlich, and Temkin adsorption isotherm as regression values were approximately unity. A monolayer physical adsorption was defined for the system.