Terminalia catappa as Effective Corrosion Resistance in Acidic Medium for Medical Stainless Steel via Experimental and Computational Approaches

Numerous industries, including the medical sector, use metals extensively. However, corrosion has had a negative impact on metals, reducing the functionality of their surfaces. Finding a suitable solution to solve this issue is highly sought after. To alleviate this issue, synthetic inhibitors are utilized, however they are detrimental to the environment. In this work, corrosion inhibition studies of Terminalia catappa (TC) extract in acidic media were done using weight loss, thermometric, and electrochemical techniques. On the identified components from the extract using GC-MS analysis, quantum chemical calculations for reactivity analysis and molecular dynamics simulation were performed. All experimental data are best suited by Langmuir's adsorption isotherm, with free energy showing spontaneity and the adsorption mechanism. The percentage inhibition of the corrosion was found to improve with an increase in the concentration of the extract, with a maximum efficiency of 83.3% using the weight loss method. According to the thermodynamic study, corrosion inhibition is concentration dependent; the higher activation energy of adsorption ranges from 40.84 to 65.86 kJ/mol, as inhibitor concentrations ranged from 0.1 to 0.5 g/L, respectively. In the electrochemical study, the Tafel polarization-determined values indicated the presence of a mixed-type corrosion inhibitor. The statistical analysis (ANOVA) revealed that there is no significant relationship among the plant components (p > 0.05). The molecular dynamics simulation predicts binding energies ranging from 1.506 to 14.05 kcal/mol for the selected bioactive compounds in plant extract responsible for plant corrosion inhibition efficiencies. This research work reported the effectiveness of Terminalia catappa (TC) as an inhibitor for medical stainless-steel implants in 1 M HCl. The GC-MS results showed phytochemical constituents that contribute to the effectiveness of the inhibitor. As a result, the overall contribution of bioactive components determines plant extract inhibition efficiency.