Effect of linking group on the corrosion inhibition performance of triazine-based cationic Gemini surfactants: Experimental and theoretical investigation

Three kinds of triazine-based cationic Gemini surfactants (TCGSII, TCGSIV and TCGSVI) with different lengths of the linking group were synthesized and characterized by FT-IR, 1 H NMR and ESI-MS. The surface activity test showed that the surface activity of the surfactants decreased with the increase in the length of the linking group from 2 to 6. At the same concentration, the corrosion inhibition rate decreased with the increase in the length of the linking group, decreasing in the following order: TCGSⅡ > TCGSⅣ > TCGSⅥ. The corrosion inhibition effect of 0.2 mM TCGSⅡ reaches 98.03 %. The adsorption of the synthesized surfactants on the surface of carbon steel conforms to the Langmuir adsorption isotherm, and included physisorption and chemisorption on the metal surface. Quantum chemical calculations and molecular dynamics simulations verify this conclusion.