Enhanced adsorption of perchlorate by gemini surfactant-modified montmorillonite: Synthesis, characterization and their adsorption mechanism
Enhanced adsorption of perchlorate by gemini surfactant-modified montmorillonite: Synthesis, characterization and their adsorption mechanism
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DOI：
10.1016/j.clay.2018.07.010
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发表时间：
2018-10-01
影响因子：
5.6
通讯作者：
Sasaki, Keiko
中科院分区：
文献类型：
--
作者：
Srinivasarao, Kancharla;Prabhu, Subbaiah Muthu;Sasaki, Keiko
有机蒙脱土(OMT)通过阴离子交换机制吸附高氯酸盐(ClO4-)。由于其独特的分子结构，每个Gemini表面活性剂(GC(N))都提供了两个阴离子交换中心。由于存在更多的阴离子交换中心，用GC(N)制备OMT比单链OMT更有可能吸收更多的ClO4。本文以三种不同链长的双子表面活性剂(CnH_2n+1(Me)(2)-C_6H_(12)-Cn H_2n+1(Me)(2)中心点2Cl)为原料合成了Gemini表面活性剂改性蒙脱土(GC(N)-Mt)，其中n分别为12、14和16，并考察了它们对水溶液中ClO_4-的吸附性能。用粉末X射线衍射仪、FT-IR、XPS、TGA和CHN分析等技术对吸附ClO4-前后的GC(N)-Mt的结构进行了表征。GC(N)-Mt对ClO4-的吸附符合Langmuir吸附等温式和准二级动力学模型。GC(16)-MT的去除能力最高，为1.08 mmol/g，且去除速度较快，1min内可达到95%，平衡时间为15min。GC(16)-MT在HCO3-、NO3-、CO32-、SO42--SiO32-、H2PO4-等多种阴离子共存的条件下，在较宽的pH范围内(2-12)保持了较高的去除能力和选择性。GC(N)-Mt结合了高的去除能力和选择性以及快速的动力学，具有很大的去除水溶液中ClO4-的潜力。
Organo-montmorillonites (OMt) adsorb perchlorate (ClO4-) through anion exchange mechanism. Each gemini surfactant (GC(n)) provides two anion exchangeable sites due to its unique molecular structure. Due to the presence of more anion exchangeable sites, the preparation of OMt with GC(n) enables the possibility for higher amount of ClO4- uptake than their single-chain counterparts. In this work, gemini surfactant modified montmorillonites (GC(n)-Mt) were synthesized using three different alkyl chain length containing gemini surfactants (CnH2n+1(Me)(2)-C6H12-CnH2n+1(Me)(2)center dot 2Cl), where n varied to 12, 14 and 16 and were examined in detail for the adsorption of ClO4- from aqueous solution. The structure of the GC(n)-Mt before and after adsorption of ClO4- was characterized by an array of techniques such as powder XRD, FT-IR, XPS, TGA and CHN analysis. The adsorption of ClO4- onto the GC(n)-Mt was best described by the Langmuir adsorption isotherm and pseudo second-order kinetic model. The GC(16)-Mt showed the highest removal capacity of 1.08 mmol/g and at a rapid rate, achieving 95% within 1 min, with an equilibrium time of 15 mins. The GC(16)-Mt retained its high removal capacity and selectivity in presence of a variety of coexisting anions such as HCO3-, NO3-, CO32-, SO42- SiO32-, and H2PO4-, and at a wide pH range (2-12). Combining the high removal capacity and selectivity with fast kinetics, the GC(n)-Mt has great potential for ClO4- removal from aqueous solutions.