Corrosion Inhibition of Copper in Acid Media using Sparfloxacin – Electrochemical Study

The potentiodynamic polarization technique and electrochemical impedance spectroscopy was used to study the inhibition efficiency of sparfloxacin on the corrosion of copper in acid solutions. Sparfloxacin exhibited good inhibition efficiency and the inhibition action was observed to be of mixed type but with more of cathodic nature. Potential of zero charge studies have been carried out to establish the mechanism of adsorption of the inhibitor onto the metal surface. From the temperature dependence of the corrosion rates, the activation energy (Ea) and the thermodynamic parameters such as the adsorption equilibrium constant (Kads), the free energy of adsorption (ΔGads), ΔS, ΔH were calculated. The free energy of adsorption close to -40 kJmol-1 indicates that the adsorption is through electrostatic coulombic attraction and chemisorption. The adsorption of sparfloxacin molecules obeyed Langmuir adsorption isotherm. Synergistic effect of KCl, KBr, and KI was investigated and enhancement in inhibition efficiency was observed on addition of KI due to synergism.