有机膨润土吸附水中重金属和有机污染物的性能及机理研究

Study of adsorption capability and mechanism of organic pollutant and heavy metal onto organobentonites

螯合剂柱撑有机膨润土IMB-TMA-Am能有效吸附水中有机物对硝基苯酚(PNP)和重金属离子Cu2+,其中IMB为内蒙膨润土;CTMA为溴化十六烷基三甲基季铵盐阳离子;Am分别为有机螯合剂乙二胺(En)、三乙烯四胺(TETA)和四乙烯五胺(TEPA)。实验结果表明:螯合剂柱撑有机膨润土对有机污染物的吸附主要表现为有机物在长碳链疏水介质中的分配,其吸附能力和膨润土内有机碳、氮含量一致;对水中重金属离子的吸附机理是Cu2+和进入膨润土层间的有机螫合剂Am形成了配合物,其吸附能力和所形成配合物的稳定性一致。

The surfactant-modified organobentonites with chelating ligands,IMB-CTMA-Am,were synthesized. IMB refers to natural bentonite obtained from Inner Mongolia of China, CTMA refers to quaternary ammonium cation surfactant of cetyltrimethylammonium bromide, and Am refers to the chelating ligands： ethylenediamine （En）, triethylenetetramine （TETA）, and tetraethylenepentamme （TEPA） ,respectively. The capabilities and mechanisms of adsorption of organic pollutan p-nitrophenol（PNP） and heavy metal ion Cu^2＋ in solution onto IMB-CTMA-Am have been investigated. The results indicate that IMB-CTMA-Am can effectively adsorb PNP and Cu^2＋ in water system simultaneously. The former is caused primarily by partion of PNP in organic phase created by hydrophobic CTMA and its capacity is in accord with the organic carbon and nitrogen contents of organobentonites,whereas the latter can be attributed to a complexation mechanism of metal ion with the chelating ligands in the interlayers of adsorbents. The adsorpion capacity of Cu^2＋ onto IMB-CTMA-AM agrees well with the stability constant of the complex formed.