Citrus aurantium leaves extracts as a sustainable corrosion inhibitor of mild steel in sulfuric acid

Abstract

Corrosion inhibition of mild steel in 1 M H2SO4 was investigated in absence and presence of Citrus aurantium leaves extracts as a friendly inhibitor. The effect of temperature, time, and inhibitor concentration were studied using weight loss technique. The result obtained revealed that Citrus aurantium leaves extracts act as an inhibitor for mild steel in H2SO4 and reduces the corrosion rate. The inhibition efficiency was found to increases with increase in inhibitor concentration whereas the temperature shows otherwise. Higher inhibition efficiency was 89% at 40 °C and 10 ml/l inhibitor concentration. The adsorption of Citrus aurantium leaves extracts was found to follow Langmuir adsorption isotherm model. The values of the free energy of adsorption was around −20 kJ/mol, which is indicative of physical adsorption between charged molecules and a charged metal. Quantum chemical calculations were also used as a theoretical support to the experimental results. Finally the scanning electron microscope and Fourier transform infrared spectroscopy were evaluated to examine surface morphology and molecular structure of inhibitor respectively.

Keywords

• Friendly inhibitor
• Weight loss
• Adsorption
• FTIR
• SEM
• Acid corrosion