Preparation And Performance Evaluation Of A Sulfate-quaternary Ammonium Salt Type Gemini Surfactant

In this paper,a sulfate-quaternary ammonium salt Zwitterionic Gemini surfactant,with different hydrophobic chain length,was designed and synthesized,and the surface-interfacial activities of the Zwitterionic Gemini surfactant and the oil displacement efficiency were studied,and some new results were obtained.Rimary amine(dodecylamine,1-tetradecylamine,1-hexadecylamine),formic acid,formaldehyde,methylamine,epichlorohydrin,chlorosulfonic acid as raw material was employed to prepared sulfate-quaternary ammonium salt Zwitterionic Gemini surfactant by ring-opening,substitution,oxidation,neutralization etc.The reaction conditions such as the reaction time,temperature,molar ratio were optimized by the single factor method.Finally,the products were characterized by FTIR spectrum and 1H-NMR spectrum.The results showed that the molecular structure of the final products were in accordance with the designed molecular structure.The surface tensions of sulfate quaternary ammonium salt Gemini surfactants were measured by suspension drop method and the results indicated that the critical micelle concentrations of C12ZGS,C14ZGS and C16ZGS were 5.4×10-4mol/L,3.1×10-4mol/L,2.8×10-4mol/L respectively.The ?cmc of C12ZGS,C14ZGS and C16ZGS increased from 28.62mN/m to32.45mN/m,and the surface tension strengthened increased with the increase of the hydrophobic chain.The experimental results of other surface actives parameters(pC20,?max,Amin)indicated that three kinds of Zwitterionic Gemini surfactants had high efficiency in reducing surface tension and strong adsorption in gas-liquid interface.Both AGads? and ?Gm? were negatives by the experimental calculation,and the results illustrated that the adsorption and micelles of the prepared Zwitterionic Gemini surfactants were spontaneous.The foam properties and emulsifying properties of C12ZGS reached the maximum at 0.5wt%,which decreased with the increase of the hydrophobic carbon chain.The Krafft points of C12ZGS,C14ZGS and C16ZGS are 3?,5?,and 9?,respectively,and they still kept clear and transparent state at low temperature.The consequence confirmed that the decomposition temperature of the sulfate-quaternary ammonium salt Gemini surfactant solution reached 150? by testing the temperature tolerance.The salt resistance of C14ZGS reached the salinity of 5×10-4mg/L,whose concentration of anti calcium and magnesium ions reached 1×10-4mg/L,and the salt resistance of C12ZGS was the second.When C16ZGS solution reached 4x10-4mg/L,there was a small amount of surfactant precipitation.By simulating the formation conditions of Yanchang oilfield,Zwitterionic Gemini surfactants flooding with different hydrophobic chain length could enhance oil recovery by 11.63%,10.91%and 9.87%,respectively on the basis of water flooding.