Investigation of the Impact of Hydrophobic Chains on the Corrosion Inhibition Properties of Triazine-Based Bisquaternary Ammonium Salts

Surface activity parameters such as critical micelle concentration (CMC), saturation adsorption (Г_max), and limiting molecular area (A_min) of three triazinyl bisquaternary ammonium salts with different hydrophobic chain lengths (C₆-2-C₆, C₈-2-C₈ and C₁₂-2-C₁₂) were analyzed from surface tension tests. The results showed that the CMC value of C₁₂-2-C₁₂ was much lower (0.026 mmol/L) than that of C₆-2-C₆ and C₈-2-C₈. The corrosion inhibition performances of three triazinyl bisquaternary ammonium salts on Q235 in 1 mol/L HCl solution were investigated by weight loss measurements and electrochemistry measurements. The results showed that the longer the hydrophobic chain length, the better the corrosion inhibition performance at the same concentration. The corrosion inhibition efficiencies of C₁₂-2-C₁₂, C₈-2-C₈ and C₆-2-C₆ at 0.2 mmol/L were 98.10%, 96.09% and 94.64%, respectively. Surface analysis and quantum chemical calculations showed that the three triazinyl bisquaternary ammonium salts can be adsorbed on the surface of carbon steel effectively to inhibit the corrosion of the carbon steel surface.