The Reseach On Interfical Behaviors Of Compound Of Petroleum Sulfonate And Betaine System At The Oil/Water Interface

Surfactants have a special molecular structure,which has both hydrophilic and lipophilic groups and can adsorb at the oil/water interface.Surfactants can be applied in oil transportation,and have high economic value and wide application prospects.Certain types of oil/water emulsions can be obtained by using particular types of surfactants,which have low viscosity,high stability,ease to demulsifie,and a wide range of application temperatures.The formation,development and demulsification of emulsions will be significantly affected by the oil/water interface properties of surfactants.The research on the properties of surfactant molecules at the oil/water interface needs to be strengthened.In this paper,the oil/water interface properties of different types of surfactants are systematically studied.The specific research contents and main conclusions are as follows:1.The interfacial tensions(IFTs)of alkyl sulfobetaine(ASB)and it mixed different types of ionic surfactants have been investigated by the spinning drop method.The experimental results show that the competitive adsorption caused by antagonistic effect appears between cationic surfactant and ASB molecules because of competitive adsorption.For anionic surfactants,they can form a strong synergistic effect with ASB due to the mixed adsorption,and the oil/water IFTs have been dramatically reduced under the “chain length compatibility effect” and the “size compatibility effect”.The ASB,anionic surfactant and natural surface-active materials mixed solutions can decline the IFTs of crude oil/water to ultralow level,which confirms the previous analysis.2.The interfacial rheological properties of anionic surfactant(KPS),ASB and their solutions against kerosene have been studied by using interfacial dilational rheological method.Experimental results show that in the case of a single surfactant solution,the maximum interfacial dilational modulus is all at a low level,and the phase angle equilibrium value of the corresponding concentration is also at a low level.This phenomenon indicates that under this system,the nature of the interfacial film is mainly determined by the interaction between the molecules of the surfactant.For the compound system,the highest interfacial dilational modulus increases significantly,while the phase angle equilibrium value of the corresponding concentration does not change significantly.This indicates that there is an obvious synergistic effect between the two surfactant molecules in the compound system,which makes the intermolecular interaction significantly enhanced.3.We have directly measured the interaction force between two kerosene droplets in KPS and ASB solutions using the reforming commercial DCAT21 tensiometer.Also studied the interfacial film strength of different surfactant molecules at the oil/water interface from the perspective of force,and the effect of different types of surfactant mixed system on the strength of the interfacial film.In the experimental range,increasing the concentration of KPS increased the strength of the interfacial film,while the concentration had little effect on ASB,but the effect of concentration on the compound system was similar to KPS.These phenomena indicate that when the difference in the structure of the surfactant leads to a large inconsistency in the strength of the interfacial film.