钠基膨润土插层改性的微结构与吸附机理

Microstructure and adsorption mechanism of intercalated modified Na-bentonite

以钠基膨润土为原料,采用十六烷基三甲基溴化铵(CTMAB)、十二烷基硫酸钠(SDS)、聚合羟基铁离子作为插层改性剂,制备出多种有机、无机、复合插层改性膨润土。运用X射线荧光光谱、扫描电镜、X射线衍射及红外光谱分析等手段研究了各插层改性膨润土的微结构变化及对苯酚和4-氯苯酚的吸附行为。结果表明:不同改性剂的插层改性效果不同,CTMAB效果最好;2种复合插层改性膨润土的层间结构有着明显的差异,CTMAB-Fe复合插层土中聚合羟基铁离子分布于有机相之外,SDS-Fe复合插层土中聚合羟基铁离子镶嵌于SDS单分子层中;各插层改性土之间吸附量的大小关系与层间距的大小关系基本一致;CTMAB插层改性膨润土对苯酚和4-氯苯酚的吸附均符合Langmuir等温方程,吸附过程均为优惠吸附。

A series of intercalated bentonites were prepared from using cetyhrimethylammonium bromide （CTMAB） , sodium dodecyl sulfate （SDS）, and Fe polycations with Na-bentonite as raw materials. X-ray fluo- rescence spectroscopy （XRF） , scanning electron microscopy （SEM） , X-ray diffraction （XRD） , and Fourier transform infrared spectroscopy （FTIR） were used to explore the microstructure of intercalated bentonites. The adsorption behaviors of phenol and 4-chlorophenol onto modified bentonites were also investigated. The results showed that different intercalated reagents had different effects, and that the CTMAB was superior. Fe ployca- tions in CTMAB-Fe intercalated bentonite were adsorbed onto the outer surface of the organic phase, whereas Fe polycations in SDS-Fe intercalated bentonite were embedded within the SDS monolayer. The adsorption capacities of intercalated bentonites corresponded to the basal spacing. The adsorption isotherm of phenol and 4-chlorophe- nol onto CTMAB intercalated bentonite were described by the Lan^muir eauation, both adsorntion nrocesses were preferential.