Exploring the role of leaves distillation waste as a green inhibitor for carbon steel in acidic environment: an integrated study.

In this study, the assessment of the leaves' co-product resulting from the hydrodistillation process was conducted to evaluate its anticorrosive potential for carbon steel in the hydrochloric acid medium. Phytochemical analysis of this biomass revealed its abundance in terms of polyphenols and flavonoids; hence the determination of total polyphenol content recorded a value of 75.4 mg GAE per g extract. This was corroborated by FTIR spectroscopy, which revealed the presence of various functional groups, thereby providing positive indications regarding the anticorrosive properties of this plant material. Electrochemical impedance spectroscopy and Tafel extrapolation analysis of polarization curves indicated that the extract from leaves reduced the corrosion rate of steel in 1 M HCl medium, reaching 78% in corrosion inhibition efficiency while following an adsorption process governed by the Langmuir isotherm. Furthermore, temperature effect investigations at a range between 293-313 K on the corrosion rate of carbon steel in the acidic medium in the presence and absence of CCLE revealed that the latter undergoes chemisorption-type adsorption on the active metal surface, thereby minimizing its degradation rate at elevated temperatures. The synergistic effect between the leaf extract and potassium iodide was examined using both electrochemical techniques, thus reflecting the cooperative abilities of the two compounds in inhibiting carbon steel corrosion. Additionally, scanning electron microscopy images of the surface state confirmed these findings, thereby providing significant insight into the anticorrosive properties of this plant material in corrosive environments. Similarly, a theoretical study using DFT and MD for the major compounds of CCLE confirmed the obtained results, concluding that the plant material derived from the hydrodistillation process of leaves exhibits remarkable corrosion inhibition capacity for carbon steel in acidic environments.