Synthesis And Performance Research Of Nonylphenol Betaine Type Amphoteric Surfactant

Basing on the molecular design, nonylphenol betaine amphoteric surfactant(NSZ) was synthesized in this article using nonylphenol, epichlorohydrin, dimethylamine and 3-chloro-2-hydroxy propyl sulfonic acid sodium as raw materials under the action of catalyst by etherification, tertiary amine and quaternary ammonium. The optimum synthesis conditions of surfactant intermediates were optimized by the single factor experiment and orthogonal test method; the structure of the final product was characterized by FT-IR; the surface tension, emulsifying properties, oil/water interfacial tension and thermal stability of the surfactant were determined, which would provide a theoretical basis for its application in the oil fields.The influences of the temperature, salinity, the surfactant concentration, the concentration of short chain alcohol and alcohol, surfactant/polymer binary system on the oil/water interfacial tension were investigated in the experiment. The results showed that the dynamic interfacial tension(DITmin) was less than 10-3 mN/m achieving the ultra-low interfacial tension when the temperature was at 50 ℃~95 ℃, the concentration of the NBAS was 0.01% ~ 0.3%(mass fraction), the concentration of Na+, Mg2+, Ca2+ was respectively 7000~3000 mg/L, 125~300 mg/L, 500~850 mg/L in the simulated water. The addition of short chain alcohol reduced the interfacial tension, and the oil-water interfacial tension decreased to 10-5 mN/m when the concentration of isopropyl alcohol(vol %) was 3%~4%. And the interfacial tension between the polymer/surfactant binary system and crude oil first decreased then increased with the increase of the mass concentration of polymer and the viscosity.The surface tension of NSZ aqueous solution at 288.15 K, 289.15 K, 308.15 K, 318.15 K, 328.15 K and different degrees of mineralization were determined adopting drop volume method, and the γ-lgc curve was obtained. The cmc、γcmc、Γmax、Amin、pC20 could be calculated by the γ-lgc curve and Gibbs adsorption formula. The calculation results indicated that γcmc and Γmax both reduced, cmc, Amin and pC20 all increased as the temperature increased. The cmc,γcmc and Amin decreased,Γmax and pC20 increased with the addition of inorganic salt. The enthalpy and entropy during the nonylphenol betaine type amphoteric surfactant micelle solution formation were calculated, which showed that the formation process of the micelle mainly driven by entropy.The emulsion performance of NSZ was investigated by water shed time method. The results showed that the emulsion performance increased first then decreased with increasing the concentration of the surfactant when the temperature was certain; it declined with the increase of temperature; and the addition of a certain amount of polymer was beneficial to the formation of emulsion.Finally, the interfacial tension of NBAS and crude oil at 85 ℃ after 2 d, 5 d, 15 d, 25 d, 35 d was measured in this paper, all the interfacial tension could remained in ultra-low orders of magnitude.