Two novel triazine-based quaternary ammonium salt Gemini surfactants as potential corrosion inhibitors for carbon steel in a sulfate-reducing bacteria solution: Experimental and theoretical studies

In this paper, two triazine ring-containing quaternary ammonium salt Gemini surfactants (C₁₂-2-C₁₂ and C₁₄-2-C₁₄) were synthesized. The minimum inhibitory concentrations against sulfate-reducing bacteria (SRB) of C₁₂-2-C₁₂, C₁₄-2-C₁₄ and dodecyl dimethyl benzyl ammonium chloride (1227) were determined using the double-dilution method. The performance of C₁₂-2-C₁₂ and C₁₄-2-C₁₄ in inhibiting carbon steel corrosion in the presence of SRB was examined, with 1227 serving as a control sample. The corrosion inhibition properties were assessed through static weight loss, electrochemical testing, and surface analysis. The interface adsorption behaviour of the corrosion inhibitor was explored via molecular dynamics simulations. Results indicate that the minimum inhibitory concentrations (MIC) of C₁₂-2-C₁₂ (0.021 mM) and C₁₄-2-C₁₄ (0.005 mM) are lower than that of 1227 (0.300 mM). The results of static weightlessness measurement reveal that the corrosion inhibition effects of the three surfactants on carbon steel soaked in SRB solution follow the order of C₁₄-2-C₁₄ > C₁₂-2-C₁₂ > 1227, with inhibition rates of 93.23 %, 88.45 %, and 76.49 % at a concentration of 0.2 mM, respectively. The adsorption behavior of these surfactants (1227, C₁₂-2-C₁₂, and C₁₄-2-C₁₄) on carbon steel surface in the presence of SRB conforms the Langmuir isotherm adsorption model. The outcomes of electrochemical experiments align with the static weight loss data. Furthermore, surface analysis results suggest that the surfactants can adsorb onto the carbon steel surface to form a protective film, thereby inhibiting SRB-induced corrosion.