Thymus Vulgarise Extract as Nontoxic Corrosion Inhibitor for Copper and á-Brass in 1 M HNO₃ Solutions

摘要

The efficiency of Thymus vulgarise extract (TVE) as a nontoxic corrosion inhibitor for copper and - brass in 1 M HNO3 has been tested by weight loss and electrochemical techniques such aspotentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemicalfrequency modulation (EFM) techniques. The calculated adsorption thermodynamic parametersindicated that the adsorption was a spontaneous, exothermic process accompanied by a decrease inentropy. The inhibition efficiency increases with increasing the concentration of the extract in HNO3solution and decreases with increasing the temperature. The adsorption of the extract on the copperand -brass surfaces in the acid solution was found to obey Langmuir adsorption isotherm. Scanningelectron microscope (SEM) results showed the formation of a protective film on the copper and - brass surfaces in the presence of TVE. The results obtained from different techniques were in goodagreement.