Investigating the Inhibition of Mild Steel Corrosion by Tectona grandis Dye Extract in Acidic Environment: Thermodynamics and Adsorption Properties

Abstract

An investigation into the corrosion inhibition potential of Tectona grandis dye extract on mild steel in 1 M HCl was conducted using weight loss and electrochemical techniques. Adsorption and thermodynamic parameters were also evaluated to understand the influence of extract structure on inhibition performance. Analysis revealed that Tectona grandis dye extract exhibited light absorption properties characteristic of a dye molecule, the Phytochemical analysis of Tectona grandis dye extract shows the presence of Alkaloids, flavonoids, saponins phenols, anthraquinones, and tannins, the result also demonstrated a direct correlation between extract concentration and inhibition efficiency, while an inverse correlation was observed with temperature. Increased activation energy in inhibited solutions supported the temperature dependence. Positive ΔH values indicated an endothermic reaction, and negative ΔGads values suggested spontaneous adsorption following the Langmuir and Freundlich isotherm models. Potentiodynamic polarization curves revealed mixed-type inhibition behavior. These findings suggest the Tectona grandis dye extract possesses promising corrosion inhibition properties.