Study On Emulsification Law Of Betaine Surfactant

Betaine is a typical amphoteric surfactant, it has unique amphiphilic molecular structure, at the same time the N atom in amphoteric surfactant with betaine has strong alkaline, so it belongs to a kind of amphoteric surfactants with the N atom with strong alkaline, and has the all characteristics of this kind of surface active agent, compared with other surfactants, betaine surfactant has many excellent performances which other types of surfactants don’t have, scholars have carried on more and more researches on it, especially in tertiary oil recovery which has transited field application from laboratory studies gradually.This paper mainly used the bottle test method, Turbiscan stability analyzer and dynamic model to study the stability of the betaine emulsion, and used studying how the Betaine effect oil-water interfacial property(interfacial tension, interfacial viscoelasticity and interfacial viscosity) to in-depth study the emulsification laws of betaine.The results showed that with the increase of the carbon number of alkyl chain of betaine, the stability of betaine emulsions increased firstly and then decreased gradually. Because of carbon number of alkyl chain of betaine was different, hydrophilic and lipophilic of betaine molecules in oil-water interface were different. When the carbon number of alkyl chain of dimethyl sulfo betaine was 14 and the carbon number of alkyl chain of dimethyl hydroxypropyl sulfo betaine was 16, betaine molecules achieved the balance between the hydrophile and lipophile in the oil-water interface, molecules which were adsorbed on the interface was the most and interfacial activity was the best in all the series, the arrange of the formed interfacial film was the closest, elasticity of interfacial film was the biggest, self-repairing capability was the strongest, strength of interfacial film was the highest, stability of formed emulsion was the best. The stability of the emulsion which was formed by two series of betaine were increased with the increase of the concentration of betaine gradually. When the betaine concentration reached the critical micelle concentration, namely concentration of tetradecyl dimethyl sulfo betaine was 0.3% and concentration of cetyl hydroxypropyl sulfo betaine was 0.2%, although betaine molecules had reached saturation in the interfacial adsorption, solution concentration had continued to increase, interfacial tension, interfacial viscoelasticity and interfacial viscosity almost changed no more, and strength of oil-water interfacial film didn’t increase no more, due to when the solution reached the critical micelle concentration, which resulted in solubilization emulsification, emulsion stability continued to strengthen with the increase of solution concentration. With the increase of betaine carbon number of alkyl chain, the stability of the emulsion which was formed by dimethyl hydroxypropyl sulfo betaine was better than the emulsion which was formed by dimethyl sulfo betaine. Dimethyl hydroxypropyl sulfo betaine is on the base of dimethyl sulfo betaine, and introduces hydroxyl on sulfopropyl groups, the function of hydrogen between hydroxyl, on the one hand, can increase the cohesion of the molecules in solution, which is easy to aggregate and wind for molecules and can increase the viscosity of the solution, on the other hand, can make the arrange between the moleculars at the interface more closely and form the hydrogen bond network between interfacial molecules, which is not easy to desorpt for interfacial molecules, and make interfacial molecules have better interfacial activity and interfacial film be more elastic, viscosity and strength of interfacial film be higher, the formed emulsions be more stable.