Citrus sinensis peel extract as corrosion inhibitor for mild steel in hydrochloric acid solution

This study investigated the corrosion inhibition properties of Citrus sinensis (CS) as a green inhibitor for mild steel in1 M HCl solution at different concentrations (100 mM, 150 mM and 200 mM). The corrosion behaviour of mild steel in the presence of absence of CS was evaluated using weight loss measurement, and scanning electron microscopy (SEM). Results of weight loss measurement showed that the corrosion rate of mild steel in 1 M HCl solution was significantly reduced with increasing concentrations of CS, inhibition efficiency reaching up to 98 %. SEM analysis revealed that the surface of mild steel in the presence of CS was covered a thin and homogenous protective film, while the surface of mild steel without CS was corroded and rough. An isothermal analysis was also carried out and the results indicated that the adsorption of CS on the mild steel surface followed the Freundlich isotherm equation. The value of n was found to be greater than 1, indicating that the adsorption of CS on the mild steel surface was favourable and increased with the inhibitor concentration. The value of the adsorption coefficient (Kf­) was found to be highest at 200 mM of CS, indicating a high adsorption capacity and strength of the CS on the mild steel surface