Three new reduced forms of synthesized Schiff bases as potent anti-corrosion inhibitors for carbon steel in artificial seawater

As part of the development of a new organic entity, we synthesized three new reduced forms of Schiff bases named 2,2’-(((2,2-dimethylpropane-1,3-diyl)bis(azanediyl)bis(methylene)disphenol (I1), 4,4’-(((2,2-dimethylpropane-1,3-diyl)bis (azanediyl)bis(methylene)bis(2-methoxyphenol) (I2), and 6,6’-(((2,2-dimethylpropane-1,3-diyl) bis(azanediyl)bis(methylene)bis(2-methoxyphenol) (I3). In order to develop new organic ligands to inhibit steel corrosion in 1M HCl solution, various electrochemical methods, such as electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP), along with surface visualization through atomic force microscopy (AFM), were employed. PDP results revealed excellent inhibition by compound I3 (71%) at a concentration of 1 mg/L. These findings were supported by the observation of a protective layer formation during prolonged immersion of steel in a corrosive solution, with or without inhibitors. In addition to gaining insights into the interaction mechanism and adsorption mode, density functional theory, Monte Carlo, and molecular dynamic simulations were conducted, revealing valuable information about the interaction of the inhibitors with the steel surface. Average surface roughness ( R a ) values obtained for the artificial seawater in the absence and presence of inhibitor are 887 nm for blank, 195 nm for I1, 158 nm for I2, and 105 nm for I3.