Adsorption Of Surfactants On Solid/Liquid Interface

This paper studies systematically the adsorption laws of ionic surfactant SDBS, nonionic surfactant TX-100 and Gemini surfactant BABS on kaolin, montmorillonite and quartz sand. Also, the effect of temperature, salt concentration, pH and other factors are considered. The adsorption mechanism and principle are studied by FTIR (Fourier Transform InfraRed) and AFM (Atom Force Microscope). The experimental results are analysed synthetically and the adsorption isotherms are fitted by two-stage adsorption model, getting the corresponding isothermal adsorption equation and adsorption parameters.Adsorption isotherms of three types of surfactant on different adsorbents have been got by using solution concentration difference method. The adsorption isotherm of ionic surfactant SDBS on kaolin and quartz sand is "L"shape, it can be divided into two stages, the adsorption quantity increases with the increasing of surfactant concentration at the very start, then the adsorption quantity reaches adsorption saturation.The adsorption isotherm of SDBS on montmorillonite and nonionic surfactant TX-100 on three sorbents is "S"shape, the adsorption isotherm can be divided into three stages. The adsorption quantity increases with the increasing of surfactant concentration at a adagio rate, then the adsorption quantity increases fast, and it reaches adsorption saturation at last. Adsorption isotherm of Gemini surfactant BABS is quite different from SDBS and TX-100. There is a maximum on the adsorption isotherm.The effect of different factors on adsorption is studied. The adsorption quantity of SDBS and TX-100 increases with the increasing of salt concentration and decreases with the increasing of pH. When heighten temperature, the adsorption quantity of SDBS decreases and TX-100 is contrary. The FTIR spectrograms of kaolin, montmorillonite, quartz sand and kaolin, montmorillonite, quartz sand complexes are studied. It proves the presence of adsorption. The adsorption shape of SDBS and TX-100 is observed by AFM (Atom Force Microscope).The adsorption isotherms of surfactants on liquid-solid interface have been classified systematically, and a nonuniform surface two step adsorption model has been developed. By using the adsorption isotherm equations derived from this model, the correlation of experimental isotherms are realized. The agreement between calculated results and experimental data is good.The innovations in the thesis are as follows:(1) This paper studies systematically the adsorption laws of surfactant with different molecule structure and the effect of other factors is studied. It can offer some direction for design of EOR (Enhance Oil Recovery) system.(2) Adsorption mechanism of surfactant with different molecule structure is observed by AFM and the effect of other factors is studied.(3) The adsorption isotherm is fitted by using two-stage adsorption model, the agreement between calculated results and experimental data is good.