Corrosion inhibition of copper in 3.5% NaCl solution by sunset yellow as a green inhibitor

The inhibitory effect of sunset yellow on the corrosion of copper surface in 3.5% NaCl solution was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy and scanning electron microscopy (SEM). Polarization curves indicated that sunset yellow acts as a mixed inhibitor. The adsorption of inhibitors obeyed Langmuir adsorption isotherm; and the thermodynamic parameters (Kads, ∆G0) were calculated and discussed. The inhibition efficiency of sunset yellow film reached 99.86% at an optimized conditions and the standard gibbs energy of 36.675 kJ/ mol indicated that the adsorption mechanism of sunset yellow on copper was a mixed mode of physical and chemical adsorption, in which the latter was dominant a chemisorption mechanism [1-2].