| With the rapid economic development, the organic-heavy metal complex contaminantshave already been the main pollution in the soil nowadays,and the clay minerals modified bythe different modifiers have been a hot topic. Our researching group had showed that the lousoil modified by the dodecyl dimethyl betaine（BS-12）could adsorb the organics-heavy metalcontaminants simultaneously, meanwhile, the complex modification with the amphotericsurfactant and other surfactants on the basis of the single amphoteric modified soil haddifferent adsorption effects from the singe modified soil. Currently, the adsorption oforganics-heavy metals pollutants on the montmorillonite modified by cationic surfactant hasbecome the main research direction on the study of modifying the clay minerals, but there areless reports on the complex modification with the amphoteric surfactant and other surfactantsto kaolinite. As a major component of clay minerals, discussing the modification mechanismof surfactant on kaolinite has a practical meaning for amphoteric-complex modified kaoliniteadsorbing pollutants.This research took the original kaolinite and BS-12modified kaolinite as the matrix,under the different pH, temperature and the ion strength treatments, to study the theadsorption of amphoteric surfactant-dodecyl dimethyl betaine（BS-12）on kaolinite and thethree different kinds of nonionic surfactant modifier adsorption on the amphoteric modifiedkaolinites. The aim was to study the modified conditions and the mechanism of the BS-12adsorption on the kaolinite and the Tween adsorption on BS-12modified kaolinites, then itcould provide a theoretical foundation for preparing the amphoteric-nonionic surfactantmodified kaolinite and its adsorption on the pollutants.The main conclusions of this thesis were as below:In the study of modification of BS-12on kaolinite,1. The total organic carbon contents of50%CEC,100%CEC,150%CEC BS-12modifiedkaolinite was5.1times,8.8times,13.8times that of the original soil, which confirmed theBS-12adsorption on kaolinite. The XRD spectra had demonstrated that there were no significant variation for50BS,100BS and150BS kaolinite, and the interlayer spacing was1.005times,1.006times and1.006times that of the original soil, so the kaolinite adsorptionmechanisms modified by BS-12may be mainly by static and hydrophobic bond.2. Henry equation was the best model to describe the adsorption of BS-12on kaolinite.The power of the adsorption came from the intermolecular and the free energy showed thatadsorption process was with spontaneous degree.3. The adsorption amount of BS-12on kaolinite increased rapidly with an increase oftime in the initial phase, then turned slowly in the slow adsorption phase and reached thebalance. It included the fast adsorption and slow adsorption. The adsorption kinetic curves ofBS-12on kaolinite balanced at4h.4. The factors showed: pH had little effect on BS-12adsorption on kaolinite,theadsorption amount increased with an increase of pH; Except0.5mol L-1, it appeared that thesmaller ionic strength, the greater adsorption amount, which meant that an increase of ionicstrength could impede the BS-12adsorption on kaolinite; At the different temperatures,theadsorption amounts ordered by20℃>10℃>40℃>30℃, when the equilibrium concentrationof BS-12was more than150mg L-1, which revealed that adsorption amount was decline withthe rise of temperature.5. The best condition of BS-12adsorption on kaolinite was at more than4h, pH6.0,temperature40℃.In the study of complex modification of non-ionic surfactant Tween on BS-12modifiedkaolinite,1. The adsorption amount of Tween20on BS-12modified kaolinite, within the initial2~8h, increased rapidly with an increase of adsorption time, then kept steady and tended tothe balance at10h.2. The adsorption amount of Tween20on50BS,100BS,150BS kaolinite increased withthe rise of the Tween20’s concentration, it stood non-linear adsorption characteristic.3. BET model was suitable to describe the adsorption characteristics of Tween on BS-12modified kaolinite.4. When the ionic strength was0.001mol L-1or0.5mol L-1, the adsorption amount ofTween20on50BS,100BS,150BS-kaolinite were the best, which meant that the ionic strength,too large or too small, could promote the Tween20adsorption on BS-12modified kaolinite;The Tween20adsorption on BS-12modified kaolinite increased with the the rise of pH, whichpresented that the best condition of pH was8.0and10; The increase of temperature couldpromote the Tween20adsorption on BS-12modified kaolinite. 5. Under the different pH conditions, the adsorption of Tween on150BS was alwaysbetter than that of100BS, and the changes of pH mainly affected the Tween20adsorption on50BS kaolinite.6. The best condition for non-ionic surfactant on amphoteric modified kaolinite was at10h, pH8.0, the ion strength of KNO30.001mol L-1, the temperature with30℃.7. The adsorption amount of Tween80on BS-12modified kaolinite was much higherthan the results of Tween20and Tween40adsorption on BS-12modified kaolinite, as forTween80and Tween20, the adsorption increased with the rise of its concentration; as forTween40, the adsorption first rose, then decreased with an increase of concentration. Sounder the lower concentration circumstance, the results of these three non-ionic surfactantswas ordered by:Tween80>Tween40>Tween20; under the higher concentration, the result wasTween80>Tween20>Tween40.8. Under the same circumstance, the adsorption amount of Tween80on50BS,100BS,150BS kaolinite had no big difference; while, the increase of modified ratio ofBS-12could promote the Tween20and Tween40adsorption on BS-12modified kaolinite. |
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