Adsorption Of Surfactants On Sandstone

In this paper,the method of surface tension and conductivity were used to measuring the CMC value of CTAB,SDBS,TX-100 and surfactant 3-sulfonated 14 alkyl dimethyl propyl betaine.The batch experiment was employed to study the adsorption of the four kinds of surfactants on the surface of sandstone.To screen the best adsorption isothermal model and dynamic model of adsorption of surfactants on sandstone,the four kinds of adsorption isotherm models(Langmuir and Freundlich,Temkin and linear adsorption isotherm)and four kinds of adsorption dynamics model(pseudo-first order kinetic model,pseudo-second order kinetic model,intra-particle diffusion and Elovich kinetics adsorption model)were adopted to fit The experiment data to the fitting.Through a lot of experiments and data analysis,the following conclusions could be obtained.(1)XRD analysis showed that the main components of the sandstone was SiO2,and by 77.49%of the slip layer of clay and 22.51%quartz.It was a kind of strong negatively charged adsorption of the adsorbent.SEM analysis indicated that the sandstone surface seemed roughness and the presence of large amounts of space.The aperture size ranged from a few microns to several microns.The CMC value of CTAB and SDBS respectively were 9.576×10-4 mol/L and 1.72×10-3 mol/L,which employed the method of conductivity.The CMC value of TX-100 and Betaine type amphoteric ionic surfactants respectively were 1.73 ×10-4 mol/L and 2.93×10-4 mol/L,which employed the method of surface tension.Surfactants CMC values:nonionic surfactant TX-100<Betaine type amphoteric ion surfactant<cationic ion surfactant CTAB<anionic surfactant SDBS.(2)The adsorption of different surfactants on sandstone exist differences.Their corresponding equilibrium adsorption quantity and adsorption equilibrium time are also different.SDBS adsorption time of arrival in balance on sandstone is 72 h,the other three kinds of surfactant adsorption on sandstone equilibration time is 48 h.Equilibrium adsorption quantity,Betaine type zwitterionic surfactant on sandstone of equilibrium adsorption quantity>cationic surfactant CTAB ion adsorption balance>non-ionic surfactant TX-100 of equilibrium adsorption quantity>anionic surfactant SDBS on sandstone of adsorption equilibrium.(3)Different adsorbent,different adsorption isotherm models.The four kinds of surfactants on the surface of the sandstone were consistent with the Freundlich adsorption isotherm adsorption model,also showed that the heterogeneity of sandstone surface.The pseudo-second order kinetic model can better describe the four types of surfactant adsorption on the surface of sandstone,the linear correlation coefficient R2>>0.99.For oil displacement process,these provided guidance for the selection of surfactant.(4)Owing to different surfactants,the sandstone adsorption mechanism was not the same.The adsorption of CTAB on the sandstone surface was the main force of electrostatic forces and hydrophobic effect.The adsorption of SDBS on the sandstone surface adsorption was the main force of ? electronic polarization and hydrophobic action.The adsorption of TX-100 on the sandstone surface adsorption was the main force of the dispersion,hydrogen bonding and hydrophobic interaction.The adsorption of Betaine type amphoteric ion surfactant adsorption on the sandstone surface was the main force of the electrostatic force.In a word,the surfactant adsorption on the sandstone is very complex.The type of the surfactant structure is the root cause of the differences caused by the adsorption behavior.