Interaction Of The Anionic Gemini Surfactant Containing A Triazine Ring With Conventional Surfactants

Gemini surfactant is a kind of highly efficient surfactant appearing in recent years. Dueto its high price, it is of great significance for its early industrialization to research theefficient complex system containing Gemini surfactant. And it is also conducive to betterunderstanding the mechanism of mixed surfactant containing Gemini.In this paper, the equilibrium surface tensions of the surfactant mixture containingtriazinyl anionic Gemini surfactants (C6-G and C8-G) and traditional anionic surfactantSDS or cationic surfactant CTAB were measured at different temperatures (25°C,30°C,35°C,40°C), by the plate method and drop volume method, respectively. The surfaceproperties and molecular interaction parameters of the complex system were acquired, thesynergism was explored, and the impact of temperature, ratio and length of Geminihydrophobic chain on the performance of mixed surfactant was analyzed. The results showthat the critical micelle concentration (cmc) of the complex system of Gemini/single-chainsurfactant decreases after first increases with the temperature rising. Interaction betweenC6-G and single-chain surfactant in both surface adsorption layer and mixed micelles isstronger than that between C8-G and single-chain surfactant. The synergistic effect for themixed surfactants with C6-G is superior to that with C8-G and the synergism forGemini/CTAB system is better than Gemini/SDS system.The dynamic surface tension of the mixture of Gemini/SDS and Gemini/CTAB at25°Cwas measured by the pendant drop method, the adsorption mechanism was studied, and theinfluence of ratio, concentration, length of Gemini hydrophobic chain and type ofsingle-chain surfactant on the dynamic adsorption of surfactant mixture was investigated.The results indicate that the adsorption process for all the compounded systems is in accordance with diffusion-controlled adsorption mechanism in both the initial stage and thelate stage, and in line with mixed kinetically controlled in the interim. With the increasingcontent of Gemini, the dynamic surface tension (DST) parameters of n and t*(reflectingmolecular diffusion from the bulk solution to the subsurface in the initial stage andmolecular adsorption from subsurface to surface in the late stage, respectively), themediated equilibrium surface tension (γm), the end time for induced area (ti) and the starttime for mediated equilibrium area (tm) for all complex systems exhibit a slight decrease,while the drop rate of surface tension (R1/2) presents a slight increasing trend, indicating theenhancement of dynamic surface activity to some extent. As the concentration increases,there exists decrease in the dynamic surface tension (DST) parameters of γm, t*, ti, tmfor allcompounded systems, while exists small increase in the value of n and substantial increasein R1/2, illustrating that dynamic surface activity is significantly improved and concentrationhas a greater impact on the dynamic adsorption. Meanwhile, the dynamic surface activityfor the mixed surfactants containing C6-G is a little higher than that containing C8-G, andthe dynamic surface activity for Gemini/SDS system is somewhat greater thanGemini/CTAB system.