ELECTROCHEMICAL an‎d QUANTUM CHEMICAL STUDY OF VANILLIN AS A GREEN CORROSION INHIBITOR FOR AA6061 IN NACL SOLUTION

The effect of vanillin on the corrosion behavior of AA6061 Al alloy in 3.5% NaCl solution was investigated using potentiodynamic polarization and electrochemical noise (EN) techniques. Vanillin offers interesting possibilities for corrosion inhibition due to its nontoxicity and high solubility in aqueous media. The best inhibition effect at 200 ppm vanillin was a marked characteristic of the inhibitor. Potentiodynamic polarization measurements indicated that the inhibitor is of mixed type. According to calculated amount of noise charges by using the standard deviation of partial signal (SDPS) at the particular interval of frequency it is possible to obtain the inhibition efficiency of an inhibitor. The inhibition efficiency values obtained from EN method show a reasonable agreement with those obtained from potentiodynamic polarization measurements. According to the quantum chemical calculations it can be deduced that the number of intermolecular hydrogen bonds is increased by increase in concentration of vanillin. This verifies the decrease in the inhibition efficiency of vanillin at high concentrations.