Utilization of Solanum Torvum Extract as a green corrosion inhibitor for enhancing mild steel resistance in acidic HCl medium: A sustainable approach

Abstract

For a long period, studies on the dissolution process of different metals have been among the most crucial topics consuming the minds of corrosion scientists and engineers. The data in this field has been constantly updated with growing industrialization and environmental pollution. Due to their exceptional corrosion resistance, which is collective by several additional needed properties such outstanding thermal and electrical conductivity, simplicity of processing and going to join, a broad variety of material properties, and coolants opposition, material and its alloys have a variety of uses and are thus used in a varied scenario. While many synthetic chemicals have corrosion-resistant qualities, most of them are quite detrimental to human strength and the environment. Many researchers and scientists underline the need of generate low-cost, harmless, and ecologically friendly organic reducing agents due of the acknowledged hazards of most synthetic organic defenders as well as strict environmental constraints. This work explores the green corrosion inhibition efficiency of Solanum Torvum Leaf extract (STL) for mild steel in 1.0 N HCl medium. At 1000 ppm, the extract achieved maximum efficiencies of 79.77% (weight loss at 333 K), 80.13% (polarization), and 77.32% (EIS). The corrosion rate decreased from 173.29 to 44.08 mmpy at 303 K and from 190.26 to 38.49 mmpy at 333 K, confirming strong protective action. Thermodynamic analysis showed activation energies of 64–68 kJ/mol and ΔG°ads values around –20 kJ/mol, indicating spontaneous mixed physical–chemical adsorption. Electrochemical studies revealed a reduction of corrosion current density from 4565 to 907 µA/cm² and an increase in charge transfer resistance from 5.30 to 23.40 Ω·cm². SEM, UV, FTIR, and EDX confirmed the formation of a protective inhibitor film. STL extract is thus established as an eco-friendly and effective green inhibitor for mild steel in acidic media.