The inhibitive effect of the investigated compounds (ethanolamine (I), diethanolamine
(II) and triethanolamine (III)) on the corrosion behavior of aluminum in 1 M H3PO4 solution using
weight loss, galvanostatic polarization and quantum chemical calculation methods was studied. The
inhibition efficiency was found to depend on type and concentration of the additives and also on
temperature. The effect of addition of halide ions to various concentrations of these compounds
has also been studied. The apparent activation energy (Ea) and other thermodynamic parameters
for the corrosion process have also been calculated and discussed. The galvanostatic polarization
data indicated that these inhibitors were of mixed-type. The slopes of the cathodic and anodic Tafel
lines (bc and ba) are approximately constant and independent of the inhibitor concentration. The
adsorption of these compounds on aluminum surface has been found to obey the Freundlich
adsorption isotherm. Some quantum chemical parameters and Mulliken charge densities for investigated
compounds were calculated by the AM1 semi-empirical method to provide further insight
into the mechanism of inhibition of the corrosion process. The theoretical results are then compared
with experimental dat |
