The efficiency of plant extract as corrosion extract for copper in 1M HNO3 medium was carried out using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The results showed variation in inhibition performance of the extract with varying concentration, immersion time and temperature. Langmuir isotherm was tested to describe the adsorption behavior of the extract on the copper surface. Potentiodynamic polarization study clearly revealed that this extract acts as a mixed type inhibitor i.e. the addition of the extract enhances both cathodic and anodic reactions. The results of the electrochemical impedance study showed a decrease in double layer capacitance and an increase in the charge transfer resistance. The results showed that rosmarinus extract could play significant role as corrosion inhibitor for copper in 1M HMO3.
Corrosion Inhibition of copper in nitric acid by 8-hydroxy-7-phenylazo-quinoline-5-sulfonicacid derivatives have been studied using weight loss and electrochemical measurements. The results showed that these derivatives act as moderate corrosion inhibitor for copper at all concentrations of these derivatives. All results indicate that the inhibition efficiency increases with increasing inhibitor concentrations. Polarization curves revealed that these derivatives are mixed type inhibitors. The adsorption of these derivatives on the surface of the copper specimens obeys Temkin adsorption isotherm. Some thermodynamic and kinetic parameters for the corrosion process were calculated and discussed. Some quantum chemical parameters for these derivatives calculated by the density function theory (DFT) semi-empirical method to provide further insight into the mechanism of inhibition of the corrosion process.