Adsorption Of Surfactants On Solid/Liquid Interface For Enhanced Oil Recovery

The adsorption laws of ionic surfactant SDBS,nonionic surfactant TX-100 and cation surfactant CTAB on silica are systematically studied in the paper.In a large scale of surfactant concentration,the effect of Ca²⁺,Mg²⁺and Na⁺ on the adsorption isotherm and kinetics of surfactants on silica are investigated.The adsorption mechanism and principle are studied by quartz crystal microbalance(QCM), molecular dynamics simulations(MD),flame atomic absorption spectrometry(FAAS) and atomic force microscopy(AFM)methods.The experimental results are analysed synthetically and the corresponding isothermal adsorption equation and adsorption kinetics parameters have been got.(1)The electrode-separated piezoelectric sensor(ESPS),an improved setup of quartz crystal microbalance(QCM),has been employed to investigate the adsorption behavior of SDBS at the hydrophilic quartz-solution interface in mineralized water medium in situ.The adsorption of positive ions on the silica surface has been verified by FAAS measurement.The experimental results show that in pure water medium. absorption of anionic surfactants SDBS on the solid surface because of lattice defects or defects of the hydrogen bond is the main absorption mechanism.Metal cations adsorbed onto the quartz surface as "structure ions" not only promote the adsorption of surfactants onto the silica surface at low concentration but also promote micelle rejection interaction,which is the main reason for desorption of surfactants with the increasing of surfactant concentration.Interaction between Na⁺ and silica surface is stronger than that between the head group of anionic surfactants SDBS and silica,and Na⁺ can be "structure ion" in the presence of anionic surfactants.(2)The electrode-separated piezoelectric sensor(ESPS),an improved setup of quartz crystal microbalance(QCM),has been employed to investigate the adsorption behavior of nonionic surfactant Triton X-100 at the hydrophilic quartz-solution interface in mineralized water medium in situ,in which the total salinity equal to 23171mg/L,containing CaCl₂ 1.3819g/L,MgCl₂ 1.0544g/L,NaCl 20.7347g/L.In a large scale of surfactant concentration,the effect of Ca²⁺,Mg²⁺and Na⁺ on the adsorption isotherm and kinetics are obviously different and a peculiar desorption of Triton X-100 at high concentration is investigated which might be important in practical process.The results get by solution depletion method are in good agreement with that obtained by ESPS.The effect of inorganic positive ions on the adsorption and desorption mechanism of Triton X-100 at the quartz-solution interface is discussed by molecular dynamics simulations(MD),flame atomic absorption spectrometry(FAAS)and atomic force microscopy(AFM)methods.(3)Quartz crystal microbalance and molecular dynamics simulation method are used in the paper to discuss the mechanism of the effect of inorganic positive ions on the adsorption of CTAB at the hydrophilic silica-solution interface.Effect of salinity,pH on adsorption mechanism of CTAB on quartz surface has been investigated.The experimental results show that in the presence of inorganic positive ions,the adsorption densities of CTAB on the silica surface decrese.(4)The adsorption kinetic of different types of surfactants in mineralized water medium has been studied in situ by QCM,both in non-mineralized and mineralized water medium,the adsorption kinetic parameters have been obtained.The results are in good agreement with the experimental value.Experimental results show that ionic surfactant SDBS adsorb onto the quartz surface more easily than cation surfactant CTAB in mineralized water medium.The innovations in the thesis are as follows:(1)Metal cations adsorbed onto the quartz surface as "structure ions" not only promote the adsorption of surfactants onto the silica surface at low concentration but also promote micelle rejection interaction,which is the main reason for desorption of surfactants with the increasing of surfactant concentration.Interaction between Na⁺ and silica surface is stronger than that between the head group of anionic surfactants SDBS and silica,and Na⁺ can be "structure ion" in the presence of anionic surfactants.(2)The effect of inorganic positive ions on the adsorption and desorption mechanism of Triton X-100 at the quartz-solution interface is discussed by molecular dynamics simulations(MD),flame atomic absorption spectrometry(FAAS).And we discuss the effect of inorganic positive ions on the adsorption mechanism.(3)In the presence of inorganic positive ions,the adsorption densities of CTAB on the silica surface decrese.