Evaluation of plant-based crude extract as environmentally friendly corrosion inhibitor

Abstract Corrosion is a persistent industrial problem, undermining metal integrity and leading to substantial economic and environmental losses. Conventional synthetic inhibitors, while effective, are often toxic, creating demand for environmentally friendly alternatives. This study evaluates the corrosion inhibition potential of Datura stramonium leaf extract on mild steel in 1 M HCl. The extract demonstrated significant efficiency, which increased with concentration, achieving optimal performance at 300 ppm across all tested temperatures (303, 313, and 323 K). The extract reached an inhibition efficiency of 96.7% at 500 ppm at 303 K. At the optimal concentration, the inhibition reached 91.8, 73.2, and 53.9% at 303, 313, and 323 K respectively. Thermodynamic analyses revealed spontaneous adsorption onto the steel surface, with efficiency decreasing moderately at higher temperatures, a characteristic of physisorption. The extract maintained appreciable inhibition at elevated temperatures (up to 58% at 323 K and 500 ppm), suggesting its ability to inhibit corrosion under harsh conditions. Adsorption studies revealed that the Langmuir isotherm most accurately described the inhibitor's behavior (R 2 = 0.993—0.999), indicating monolayer adsorption on a homogeneous metal surface. Electrochemical measurements indicate that the leaf extract acts as an effective mixed-type corrosion inhibitor for mild steel in 1 M HCl. The inhibition performance is attributed to phytochemicals containing oxygen and nitrogen donor atoms and aromatic rings, which facilitate effective surface coverage and the formation of a stable protective film on the metal surface, as confirmed by morphological studies of the formed film. These findings establish Datura stramonium leaf extract as a plant-based, cost-effective, and environmentally friendly alternative to conventional synthetic inhibitors, consistent with green chemistry and sustainable industrial practice.