Non-toxic bisacodyl as an effective corrosion inhibitor for mild steel in 1 M HCl: Thermodynamic, electrochemical, SEM, EDX, AFM, FT-IR, DFT and molecular dynamics simulation studies

Abstract

Corrosion inhibiting effect of Bisacodyl was studied on mild steel in 1 M hydrochloric acid by weight loss, polarization, open circuit potential and electrochemical impedance spectroscopy measurements. Polarization curves indicated that studied inhibitor was acting as mixed type. The thermodynamic parameters such as activation energy (Ea), adsorption equilibrium constant (Kads), free energy of adsorption (ΔG0ads), enthalpy (ΔH0ads) and entropy (ΔS0ads) of activation were calculated and discussed. The adsorption of the inhibitor on the metal surface obeyed Langmuir's and Temkin adsorption isotherm. SEM, EDX and AFM observations confirmed the existence of protective film on the metal surface. The Quantum chemical, Molecular dynamic stimulation and FT-IR studies fairly well agreed with the electrochemical measurements.