4-Hydroxycoumarin derivatives as corrosion inhibitors for copper in nitric acid solutions

The corrosion behavior of copper in 1m hno3 and in the presence of 4-hydroxycoumarin derivatives has been investigated using,electrochemical impedance spectroscopy (eis),potentiodynamic polarization,electrochemical frequency modulation (efm) and weight loss techniques. results of eis showed the increase in the charge transfer resistance and the decrease in the double layer capacitance. polarization studies showed that,these compounds act as mixed-type inhibitors. inhibition efficiency of these compounds has been found to vary with concentration of the 4-hydroxycoumarin derivatives and temperature. the adsorption of these compounds on the surface of copper from the acid solution has been found to obey temkin adsorption isotherm. the thermodynamic activation parameters of copper corrosion in 1m hno3 were determined and discussed. the results obtained from all tested techniques were in good agreement.