Investigation of two triazine derivatives as potential eco-friendly corrosion inhibitors for copper in artificial seawater

The inhibiting action of 6-N,N-bis(6-methylheptyl)amine-1,3,5-triazine-2,4-dithiolmono-sodium, (iso-DON) and 6-dibutylamino-1,3,5-triazine-2,4-dithiol monosodium (DBN) on the corrosion of copper in artificial seawater (3.5 wt% NaCl solution) has been investigated using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) methods and scanning electron microscopy (SEM) techniques. The results from weight loss and electrochemical measurements consistently identify that both iso-DON and DBN exhibit good performance as inhibitor for copper corrosion in 3.5 wt% NaCl solution and the inhibition efficiency increases with the increase in inhibitor concentration. Potentiodynamic polarization measurements reveal that the studied triazine dithiol derivatives act as mix-type inhibitors, and the maximum value of the inhibition efficiency was obtained (93 % for iso-DON and 95 % for DBN) when the inhibitor concentration reaches 1.5 mM. EIS imply that the corrosion of copper in NaCl solution is influenced by charge transfer. The adsorption of iso-DON and DBN molecules on copper surface was found to obey the Langmuir adsorption isotherm. Parameters for adsorption indicate a strong interaction between inhibitor molecules and copper surface, and the negative values of ΔGθ reveal the spontaneous adsorption of iso-DON and DBN on copper surface.