(163d) Significance of ??Electrons in the Adsorption of Corrosion Inhibitors for Carbon Steel Rebars in Simulated Concrete Pore Solution

The significance of π‒bond electrons was illustrated by electrochemical testing and a quantitative structure property relation using atomic signatures for different organic corrosion inhibitors. Amine, alkanolamine, and carboxylate corrosion inhibitors were electrochemically tested on carbon steel rebars in 0.1 M Cl^‒ contaminated deaerated simulated concrete pore solution using a cyclic potentiodynamic polarization. According to electrochemical results, carboxylates had the best inhibitive performance followed by amines and alkanolamines. It was found that carboxylates were able to complex with ferrous ions producing an adsorption film on the electrode interface, hence protecting it from Cl^‒ induced attacks. This was attributed to the presence of π‒bond electrons in the carboxyl group, increasing the molecule’s tendency to donate electrons to the surface of the carbon steel rebar. This phenomenon was further corroborated using Density Functional Theory. Moreover, a novel approach was utilized using a quantitative structure property relation using atomic Signatures. This approach correlates the occurrences of atomic Signatures in a data set to a property of interest (i.e. pitting potential) using a forward stepping multilinear regression. Based on the available models generated at height‒0,1 and, 2. The atomic Signature fragment capturing π–bond was the most influential of all the fragments, which underscores the significance of π–bond electrons in the adsorption process. It was demonstrated that the [O](=[C]) atomic Signature plays a crucial role in the inhibition process at all heights, corroborating the experimental results. This phenomenon was further illustrated by using different surface characterization techniques.