Interactions Between Ionic Liquid Surfactant And Crude Oil And Its Fractions

The room temperature ionic liquid(RTILs) as a new kind of green solvent，have receivedextensive attention in many areas. The study of chemical nature of the interface and theformation of ordered aggregation of ionic liquid surfactant has theoretical and practicalsignificance in demusification and tertiary oil recovery.Three kinds of midazole-based ionic liquids bromo-1-alkyl-3-Methy limidazolium(CnmimBr) surfactants were synthesized by one-pot, whose structures were characterized byIR and TG. The themelting points of C12mimBr、C14mimBr and C16mimBr were36.8℃、48.5℃、63.9℃separately. CnmimBr also has good surface activity. The critical micelleconcentration (CMC) of CnmimBr were10mmol·dm-3、3.0mmol·dm-3、0.65mmol·dm-3separately. And each of whose molecule occupied the average area(Amin) reduced as the lengthof hydrophobic chain, while the saturated adsorptioncapacity (Γmax) increased when they wereadsorbed on the surface. The mixtures of CnmimBr and SDBS solution were studied throughelectrical conductivity measurements and surface tension measurements. The addition ofCnmimBr to SDBS/H20system resulted the Surface tension(γ) decreased remarkably whilethe the critical micelle concentration (CMC) increased.The influence of CnmimBr on crude oil and its fractions(Asphaltenes fraction, Saturatesfraction, Aromatics fraction and Colloid fraction) was studied by Langmuir-Blodgett(L-B)technology. The results showed that CnmimBr could decrease remarkably the oil-waterinterfacial film pressure of crude oil and its fractions. And the ability of reduced interfacialfilm pressure is C12mimBr＜C14mimBr＜C16mimBr.Dilatonal viscoelasticity of oil-water interface film of CnmimBr on crude oil and itsfractions was studied by using L-B method. As the concentration of C16mimBr increased, theinterface film of crude oil and its fractions dilational modulus(ε), the dilationalviscosity(ηd)deceased at first then increased, the dilational elasticity(εd) increased. As thedilational frequency(w) increased, the interface film of crude oil and its fractions dilationalmodulus(ε), the dilational viscosity(ηd)increased, the dilational elasticity(εd) increased firstthen increased.