Synthesis And Performance Evaluation Of Reactive Gemini Surfactants

Gemini surfactants are a new type of surfactant. Compared with traditional surfactants, its unique structure gives them higher surface activity and low critical micelle concentration (cmc), which is the present flooding surfactants can not be compared. Thus gemini surfactants has great potential in enhanced oil recovery(EOR). In this paper, on the basis of extensive literature research, the basic properties of Gemini cationic surfactants was studied. Hope to provide theoretical support and guidance for Gemini surfactants'application in the field of EOR.A series of cationic gemini surfactants named chloride-N,N,N',N'-four hydroxyethyl-N,N'-dialkyl-2- hydroxy-propylenediamine was synthesized by two step reactions, taking the diethanolamine, bromoalkane(carbon number is 8,12,16), the epichlorohydrine as raw material. The structure of synthesized product was investigated by means of IR and 1HNMR spectroscopies. The surface activity of synthesized surfactants was studied. Results showed that, their cmc is 0.31-10.5mmol/L, the lowest surface tension (γcmc) is 20.6-28.3mN/m. So they have much higher surface activity than conventional surfactants. For comparison, the surface activity of gemini surfactants named N,N,N',N'- four methyl-N,N'- two alkyl propylenediamine was determined. The results show that the short-chain connected to N atoms in the molecular structure of surfactants have impact on surface activity of it.Each of the two types of gemini surfactant was mixed with traditional anionic surfactants. The surface activity of mixed systems with different ratio were inspected. The mixed system with higher surface activity was identified when the gemini surfactants'molar ratio was 30% in the complex system with SDS. The result indicated that the extent of synergistic effect of complex systems varies from the relative content of each component, also from the molecular structure of the traditional anionic surfactants. The better complex system's displacement efficiency can be evaluated by core displacement experiments at room temperature. Experimental results showed that recovery ratio of the complex system can be raised by 8.7%, which was far higher than the single traditional surfactant's displacement efficiency.