adsorption study of doxycycline to protect the mild steel surface from sulphuric acid solution

The ability of doxycycline to prevent corrosion of mild steel in 0.5 m sulphuric acid was investigated by using weight loss measurements, polarization resistance, tafel polarization, and eis (electrochemical impedance spectroscopy). doxycycline was a powerful inhibitor for mild steel corrosion, with an effectiveness of 99.2 % at 4.5×10-4 m. the thermodynamic parameters were computed and discussed to evaluate the process of inhibition. the drug fits the langmuir isotherm. potentiodynamic polarization studies indicate that it acts as a mixed-type inhibitor. the electrochemical impedance spectroscopy reveals that raising the concentration of doxycycline amplifies the charge transfer resistance while dropping the double-layer capacitance. surface morphology investigations were done with atomic force microscopy (afm) on metal surfaces.