Synthesis, characterization of some ethoxylated tolyltriazole derivatives and evaluation of their performance as corrosion inhibitors for Cu-10Al alloy in seawater

Two of ethoxylated tolyltriazole non ionic surfactants namely; TTA (12) and TTA (24) were synthesized (where 12 and 24 are the number of ethylene oxide units groups bonded to tolyltriazole molecule). The chemical structure of the synthesized compounds was confirmed by FTIR and 1H NMR spectroscopic techniques. The performance of the two synthesized tolyltriazole derivatives was evaluated as corrosion inhibitors for Cu-10Al alloy in seawater and compared with the performance of tolyltriazole (TTA). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used in this evaluation. The results showed enhancement in inhibition efficiency with increasing the number of ethylene oxide units in the surfactant molecule. Potentiodynamic polarization data showed that the surfactants under investigation act as mixed type inhibitors. Also it was found that the inhibition efficiency increased by addition of Cu2+ions to the solution containing inhibitor and reached to 97%. This behavior can be attributed to the synergistic effect between Cu2+ions and inhibitor. The data obtained from EIS were analyzed to give a suitable equivalent circuit (EC). Finally, the surface morphology of Cu-10Al alloy immersed in sea water in the absence and presence of inhibitor molecule was examined by SEM images to through some light on the nature of the protective layer formed on the surface that isolate it from the aggressive environment.