阴-阳离子表面活性剂复合柱撑蒙脱石的制备与表征

THE PREPARATION AND CHARACTERIZATION OF ANION-CATION SURFACTANTS MODIFIED MONTMORILLONITE

利用阳离子表面活性剂——十六烷基三甲基溴化铵(HDTMAB)和阴离子表面活性剂——十二烷基磺酸钠(SDS)制备了一系列阴-阳离子表面活性剂复合柱撑蒙脱石。同时采用多种测试手段(碳、硫、硅含量分析、X射线衍射分析和热分析)对产物进行结构表征和性能分析。结果表明,SDS难以单独进入蒙脱石层间,但与HDTMAB作用后,SDS可以进入到蒙脱石结构层间。在复合物中有机碳量较低时,SDS对有机碳含量增加贡献明显,但其柱撑效率随着HDTMAB加入量增加而下降,至HDTMAB加入量大于3倍阳离子交换容量(CEC)时趋于平衡。在复合物中有机碳量较高时,HDTMAB负载量有下降的趋势,至HDTMAB加入量大于3倍阳离子交换容量时趋于平衡。SDS进入结构层内总体提高蒙脱石的有机碳含量,明显地增加产物的层间高度,并且改善其热稳定性。

A series of anion-cation surfactants modified organoclays were prepared by incorporating both cationic surfactant, hexadecyltrimethylammonium bromide （HDTMAB）, and anionic surfactant, sodiumdodecyl sulfonate （SDS）, to montmorillonites. A combination of elemental analysis, X-ray diffraction and thermogravimetric analysis was adopted to characterize the resulting organoclays. The organic carbon contents of the HDTMAB-SDS organoclays are further improved as compared with only HDTMAB modified organoclays. The XRD patterns showed that the basal spacings are expanded with the intercalation of surfactants. The characterization results indicated that SDS cannot be intercalated into montmorillonites whereas anionic surfactants can be transferred into the interlayer of montmorillonite by pre-modification with cationic surfactants. In derivative thermogravimetric curves, a new peak is displayed, which is located at 400 -430 ℃. This is related to forming composites with enhanced thermal stability.