Okra leaves extract as green corrosion inhibitor for steel in sulfuric acid: Gravimetric, electrochemical, and surface morphological investigations

Utilizing plant extracts as an alternative source for corrosion inhibitors holds significant promise in minimizing the risk of corrosion. In this study, an okra leaf extract (OLE) was employed as a corrosion inhibitor for N80 steel in 1.0 M H2SO4. The corrosion rate was assessed concerning temperature (30, 40, 50, and 60 °C) and inhibitor concentrations (blank, 25, 50, 75, and 100 ml/l) through weight loss and electrochemical polarization techniques. The results indicated that OLE functions as a mixed-type corrosion inhibitor, with corrosion rates increasing with temperature and decreasing with inhibitor concentration. The maximum corrosion inhibition efficiency reached 96 % at 30 °C and 100 ml/l. Adsorption studies revealed that OLE physically adsorbed onto the mild steel surface, following the Langmuir adsorption isotherm. Gravimetrical and electrochemical techniques were confirmed by FTIR and UV measurements, which showed the presence of a protective layer on the metal surface. Optical microscopy, AFM, and SEM images demonstrated the formation of a protective layer on the metal surface. Thermogravimetric analysis (TGA) highlighted the thermal stability exhibited by inhibitor molecules, which showed that OLE was thermally stable up to 85 °C.