Quantum molecular design and experimental testing of a high-performance zwitterionic corrosion inhibitor for oxidized iron surfaces

• Published in: Journal of molecular graphics & modelling 2019-12, Vol.93, p.107444-107444, Article 107444
• Main Authors: Cerón-Camacho, Ricardo, Cisneros-Dévora, Rodolfo, Martínez-Magadán, José-Manuel, Servín-Nájera, Ana G., Ramírez-Pérez, Jorge F., Hernández-Altamirano, Raúl, Zamudio-Rivera, Luis S., Oviedo-Roa, Raúl
• Format: Article
• Language: English
• ISSN: 1093-3263; 1873-4243
• DOI: 10.1016/j.jmgm.2019.107444

A zwitterionic-based chemical, the 3,3’-(octadecylamino)dipropionic acid, was quantum-theoretically designed to be applied as a corrosion inhibitor for protecting oxidized iron surfaces against the attack of very corrosive gasolines. Its performance, as well as those of worldwide-employed nitrogen-free carboxylic-diacid-based corrosion inhibitors, were experimentally evaluated and compared. Through Density-Functional-Theory calculations of the molecular interactions of the corrosion inhibitors with an iron-oxide cluster model, along with the experimental corrosion-inhibiting evaluations, it is revealed that the zwitterionic-based chemical substantially overcomes the performance of nitrogen-free chemicals. It is shown by the theoretical results that the two carboxylic heads of either, the zwitterionic-based or the nitrogen-free corrosion inhibitors, reinforce the octahedral coordination around the exposed Fe3+ atom of the iron oxide. Furthermore, when the zwitterionic-based chemical is bonded to the Fe3+ atom, a two-rings chelate is formed, in contrast to the one-ring chelate formed by the nitrogen-free corrosion inhibitors. Finally, it is theoretically predicted that oleic solvents improve the performance of the zwitterionic-based corrosion inhibitor because preclude the steric hindrance of nitrogen. [Display omitted] •Corrosion inhibitors based on dicarboxylic acids form one-ring chelates with Fe3+.•Zwitterionic inhibitors based on dipropionic acids form two-ring chelates with Fe3+.•Corrosion-inhibitor performing of zwitterions overcome that of dicarboxylic compounds.