水滑石类材料的插层组装及对酚类化合物的增强吸附性能

发布时间：2018-04-25 02:33

本文选题：水滑石 + 有机改性　；参考：《武汉理工大学》2015年硕士论文

【摘要】：水滑石材料具有较大的内表面和孔径、交换容量大、耐高温等优点,在阻燃剂、医药、离子交换与水污染净化等领域得到广泛应用。本论文探索水滑石材料的可控制备方法,以获取多孔、大比表面积、层间疏水性等吸附材料,以增强其对水中对硝基苯酚(PNP)的吸附性能,主要研究结果如下:以六亚甲基四胺(HMT)为沉淀剂,十二烷基苯磺酸钠(SDBS)为表面活性剂,分别以酒石酸钠、柠檬酸钠、水杨酸钠为结构导向剂,通过水热法合成了分等级多孔锌铝系水滑石ZnAl-LDH材料。表征结果表明,SDBS插层ZnAl-LDH材料在结构导向剂的调节下,形貌可从不规则纳米片分别转变成类球状结构,绒球状和中空微球结构。其中,经过水杨酸钠改性的微球型疏水性ZnAl-LDH具有最大的比表面积(128.9 m2/g)和孔体积(0.37 cm3/g),对PNP的吸附效率也最高,其饱和吸附量为101.6 mg/g。分别以酒石酸钠,柠檬酸钠和十二烷基苯磺酸钠(SDBS)为插层改性剂,六亚甲基四胺(HMT)为沉淀剂,运用一步水热法制备得到三种不同改性剂阴离子插层的锌铝水滑石。分别运用X射线衍射(XRD)和扫描电镜(SEM),以及N2的吸附-脱附等温技术对样品的形貌和结构特性进行了表征,结果表明,改性后的三种水滑石的形貌及比表面积各异,其中由酒石酸钠改性的锌铝水滑石具有最大的比表面积(176.9 m2/g),其对硝基苯酚的吸附效率也最高,其饱和吸附量为154.4 mg/g。改性后的锌铝水滑石的层间距分别由0.757 nm增大到2.94,3.42,3.73 nm,表明三种改性剂成功插层进水滑石层间。通过对对硝基苯酚的静态吸附实验可知,经过三种改性剂改性后的锌铝水滑石对对硝基苯酚的吸附效率增大,吸附速率增加,吸附动力学行为符合准二级动力学方程,其吸附等温线符合Langmuir等温吸附模型。用共沉淀和离子交换法两种方法制备了环糊精(CMCD)插层改性的锌铝水滑石。经环糊精改性后,原始的硝酸根型的锌铝水滑石的层间距由原来的0.874nm增大到1.60 nm,表明CMCD与层板间硝酸根发生了离子交换,成功插入水滑石层间,并在层间以轴线垂直于水滑石层板的方式排列。吸附实验表明,环糊精插层改性后的锌铝水滑石相对于原始的硝酸根型的水滑石,对对硝基苯酚的吸附速率加快,吸附效率提高,吸附量也增大,由原来的68.3 mg/g增大到98.0mg/g,这是由于环糊精分子具有的圆桶形结构,空腔内部为疏水性,外表面为亲水性,这种特殊的分子结构使的环糊精分子也可以作为“主体”,通过分子间相互作用(如电荷传递、范德华力、疏水作用和醚氧键等)与“客体”分子形成包合物,从而提高其对对硝基苯酚的吸附量,其对对硝基苯酚的等温吸附与Freundlich等温模型更吻合,吸附动力学行为符合准二级动力学方程。
[Abstract]:Hydrotalcite is widely used in the fields of flame retardants, medicine, ion exchange and water pollution purification because of its large inner surface and pore size, large exchange capacity, high temperature resistance and so on. In this paper, the controllable preparation method of hydrotalcite was explored to obtain porous, large specific surface area and interlaminar hydrophobicity in order to enhance the adsorption properties of p-nitrophenol PNPs in water. The main results are as follows: using hexamethylenetetramine (HMT) as precipitant, sodium dodecylbenzene sulfonate (SDBS) as surfactant, sodium tartrate, sodium citrate and sodium salicylate as structural guides, respectively. The porous zinc-aluminum hydrotalcite ZnAl-LDH was synthesized by hydrothermal method. The characterization results show that the morphology of the ZnAl-LDH intercalated with SDBs can be changed from irregular nanochips to spherical, velvet and hollow microspheres with the adjustment of the structure guidance agent. Among them, sodium salicylate modified microsphere hydrophobic ZnAl-LDH has the largest specific surface area of 128.9 m2 / g) and pore volume of 0.37 cm ~ 3 / g 路g ~ (-1). The adsorption efficiency of PNP is also the highest, and its saturated adsorption capacity is 101.6 mg / g. Using sodium tartrate, sodium citrate and sodium dodecyl benzene sulfonate as intercalation modifiers and hexamethylenetetramine HMTas as precipitators, three kinds of anionic intercalation zinc-aluminum hydrotalcite with different modifiers were prepared by one step hydrothermal method. The morphology and structure of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and adsorption desorption isotherms of N2, respectively. The results showed that the morphology and specific surface area of the modified three kinds of hydrotalcite were different. The zinc-aluminum hydrotalcite modified by sodium tartrate has the largest specific surface area of 176.9 m2 / g and the highest adsorption efficiency of p-nitrophenol, and its saturated adsorption capacity is 154.4 mg / g. The interlayer spacing of the modified zinc-aluminum hydrotalcite increased from 0.757 nm to 2.94 ~ 3.42 ~ 3.73 nm, respectively, indicating that the three modifiers successfully intercalated the influent talc layers. Through the static adsorption experiment of p-nitrophenol, it is known that the adsorption efficiency of p-nitrophenol is increased and the adsorption rate of p-nitrophenol is increased by the modified zinc-aluminum hydrotalcite after three modifiers, and the adsorption kinetic behavior accords with the quasi-second-order kinetic equation. The adsorption isotherm is in accordance with the Langmuir isothermal adsorption model. Zinc and aluminum hydrotalcite modified by cyclodextrin (CMCD) intercalation were prepared by coprecipitation and ion exchange method. After modified by cyclodextrin, the interlayer spacing of the original zinc-aluminum hydrotalcite was increased from the original 0.874nm to 1.60 nm, which indicated that the exchange of nitrate between CMCD and the laminates took place, and the interlayer was successfully inserted into the hydrotalcite. The layers are arranged in an axis perpendicular to the hydrotalcite laminates. The adsorption experiments showed that the adsorption rate of p-nitrophenol was accelerated, the adsorption efficiency and the amount of adsorption of the modified zinc-aluminum hydrotalcite were increased compared with the original nitric acid hydrotalcite, the adsorption efficiency and the adsorption capacity of the modified zinc-aluminum hydrotalcite were also increased. The increase from the original 68.3 mg/g to 98.0 mg / g is due to the cylindrical structure of cyclodextrin, the hydrophobicity in the cavity and the hydrophilicity on the outer surface, so that the cyclodextrin molecule can also be used as the "main body". By means of intermolecular interactions (such as charge transfer, van der Waals force, hydrophobic interaction, ether oxygen bond, etc.), inclusion complexes are formed with "guest" molecules, thus increasing the adsorption capacity of p-nitrophenol. The isothermal adsorption of p-nitrophenol is in good agreement with the Freundlich isothermal model, and the adsorption kinetics is in accordance with the quasi-second-order kinetic equation.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;O647.3

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