用有机螯合剂(CA)和十六烷基三甲基溴化铵(HDTMAB)共同改性膨润土(IMB),制得一系列膨润土纳米复合材料IMB-HDTMA-CA。X射线衍射(XRD)、热分析(TG-DTA)、红外光谱(FTIR)以及N2-吸附脱附技术等研究发现,HDTMA^+和CA已稳定柱撑在膨润土的片层结构中,其层间距增大、比表面积减小而疏水性增强。吸附实验表明,IMB-HDTMA-CA能协同吸附水中有机物对硝基苯酚(PNP)和重金属镉(Cd^2+)。对水中对硝基苯酚的吸附源于PNP在膨润土层间有机相中分配作用的增加,其吸附容量和膨润土内有机碳含量和层间距大小一致,而与比表面积无关,依次为IMB-HDTMA-TEPA〉IMB-HDTMA-TETA〉IMB-HDTMA-En〉IMB-HDTMA》IMB;FTIR图谱显示,IMB-HDTMA-CA吸附Cd^2+后的N-H吸收峰向低频方向移动,其吸附能力和所形成配合物的稳定性一致。
A series of bentonite nanocomposites IMB-HDTMA-CA have been synthesized by modifying bentonite (IMB) with organic chelating agents (CA) and hexadecyltrimethylammonium bromide (HDTMAB). The sorbents were characterized by XRD, TG-DTA, FTIR and N2 adsorption/desorption. The results indicated that HDTMA^+ and CA were intercalated into the interlayer of bentonites stably, the basal spacing was swollen, the specific surface area was decreased, and the hydrophobic ability was enhanced after modification. The sorption experiments found that IMB- HDTMA-CA could adsorb para-nitrophenol (PNP) and Cd^2+ in water system simultaneously. PNP sorption onto IMB- HDTMA-CA was caused primarily by partitioning into an organic phase; the sorption capacity was in accord with organic carbon contents and basal spacings, but independent of specific surface areas of bentonite nanocomposites IMB-HDTMA-CA, the magnitude sequence was IMB-HDTMA-TEPA〉IMB-HDTMA-TETA〉IMB-HDTMA-En〉IMB- HDTMA》IMB. FTIR study revealed that the N-H vibrational frequency was downshifted after Cd^2+ sorption. The sorption capacity of Cd^2+ onto IMB-HDTMA-CA agrees with the stability constant of the complex formed in the interlayer of IMB-HDTMA-CA.