Thermodynamic and electrochemical investigation of inhibition efficiency of green corrosion inhibitor and its comparison with synthetic dyes on MS in acidic medium

Abstract

The expedition of Green corrosion inhibitors has been initiated by the organic corrosion inhibitor as green corrosion inhibitors are bio-degradable, eco-friendly and environmental acceptable bereft of heavy metals and other toxic products. Moreover, the products obtained from the plant are cost-effective, readily available and can be renewed. In the following study, the inhibition performance of natural inhibitor i.e., black pepper extract and synthetic inhibitors i.e., thoron Dye and Phenosafranin dye on mild steel surfaces in hydrochloric acid (HCl) were inspected and for this purpose, weight loss measurements, Electrochemical Impedance Measurements (EIS) and Potentiodynamic Polarization study at different concentrations and at different temperatures were recruited. Among these inhibitors, the best inhibition efficiency was shown by black pepper extract i.e., 97% in 1 M HCl. In the prolongation of our work, entropy (ΔS), enthalpy (ΔH), gibbs free energy (ΔG), activation energy (Ea) and pre-exponential factor (A) of the reaction were calculated and it is concluded that the inhibition process follows physical adsorption on the surface and the adsorption process follows Langmuir and Tempkin isotherms also. For surface analysis, Atomic Force Microscopy (AFM) was done. The present study concludes that natural inhibitor i.e., Black pepper extract which contains alkaloid piperine becomes quite impressive in decelerating the effect of corrosion on mild steel surfaces in acidic environments as compared to synthetic inhibitors.