Evaluating the performance of corn peptone in preventing the corrosion of mild steel immersed in HCl

Abstract

The effects of biodegradable corn peptone on the corrosion behavior of mild steel in 0.1M HCl were evaluated. The results from the weight loss experiments indicate that changing the amount of corn peptone from 50 to 500 ppm considerably decreased the corrosion rate of the coupons from 28.24 to 4.67 mpy. However, heating the solutions had negative effects on this trend. According to the calculations, dissolving the inhibitor modified the thermodynamic parameters of the corrosion phenomenon. In addition, the adsorption of corn peptone was best fitted with the Langmuir isotherm. The Tafel polarization plots revealed that the presence of corn peptone decreased the corrosion current density from 134.9 to 6.7 µA cm⁻². This was compatible with the electrochemical impedance spectroscopy data. Furthermore, X-ray photoelectron spectroscopy analysis confirmed the adsorption of the tested peptone on the surface of the working electrodes, which based on the atomic force microscope images, reduced the surface roughness of the specimens.