工程纳米材料对铅和钒吸附性能的研究

发布时间：2018-03-15 20:32

本文选题：氧化锌　切入点：二氧化钛　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：纳米材料及其功能化复合材料因其表面富含多种官能团,而被广泛的应用于吸附研究领域。着重于高效吸附材料的探索而对其表面基团进行修饰,不同的材料结构和不同表面的基团对于重金属污染的吸附,已经成为新型吸附材料的研究重点。本文通过对工程纳米材料(氧化锌(ZnO)、二氧化钛(TiO_2)、氧化石墨烯(GO))及其复合材料(氧化锌-氧化石墨烯(ZnO-GO)、氧化锌-壳聚糖(ZnO-CS)、氧化石墨烯-壳聚糖(GO-CS)、二氧化钛-壳聚糖(TiO_2-CS))进行扫描电镜能谱分析(SEM-EDS)、红外光谱分析(FTIR)和X射线电子能谱分析(XPS)表征及动力学、等温吸附模型拟合,研究在吸附重金属铅和钒的过程中材料表面官能团的作用,探讨阴阳离子吸附的差异。以路易斯酸碱理论为基础,为制备新型高效吸附材料,提供理论依据。本研究主要取得以下结论:1.ZnO、TiO_2及ZnO-GO、ZnO-CS、GO-CS、TiO_2-CS六种材料对铅和钒的吸附均符合二级动力学过程(R20.99),等温拟合结果符合Langmuir和Freundlich模型,其中RL1说明反应易于进行,吉普斯自由能均小于零,吸附反应自发进行。2.金属氧化物纳米材料因其结构差异而表现出不同的吸附特性。在p H=6.5时,纳米ZnO表面带正电、纳米TiO_2表面带负电;纳米ZnO及TiO_2对铅和钒饱和吸附量分别为192.64、49.90 mg·g-1与433.13、369.10 mg·g-1。吸附过程受物理化学因素影响,铅和钒的吸附作用主要发生在纳米材料的终端羟基上;吸附钒的过程中易于结合水分子形成水分子网,而吸附铅的过程中结合水分子的能力较弱。3.纳米ZnO结合不同的材料可改变其表面性质,从而改变吸附性能。ZnO-GO与ZnO-CS复合材料对铅和钒的饱和吸附量分别为917.83、96.50 mg·g-1与663.73、211.50 mg·g-1ZnO-GO以氢键形式连接,使材料表面存在Zn-OH和C-OH,吸附铅后两种羟基等量减小,吸附钒后吸附水含量增加;ZnO-CS同样以氢键形式连接,XPS结果显示,对铅的吸附作用主要发生在Zn-OH和C-OH及C-O-C上,而对钒的吸附主要发生在Zn-OH上。4.利用戊二醛(连接羟基和氨基交联)CS与GO和ZnO,从而改变材料的吸附性能。CS-GO与CS-TiO_2对铅和钒饱和吸附量分别为32.88、86.75 mg·g-1与18.52、56.73 mg·g-1;CS-GO对铅和钒的吸附主要发生在CS-羟基上,GO-OH由于C-O-C被打开而含量增加;CS-TiO_2中TiO_2中的终端羟基被戊二醛交联,桥连羟基并不参与反应,CS-TiO_2吸附铅作用在C-O-C和C-OH以及Ti-OH(终端)上,而吸附钒作用在-NH2上。5.在XPSO1s分峰中,结合水含量在吸附重金属前后发生变化。以含氧负离子形式存在的重金属钒,V作为路易斯酸性位点,O作为路易斯碱性位点,能够吸附解离水中的OH-与H+,使得六种材料吸附钒后更容易结合水分子而使结合水含量增加;以阳离子为主要形式的重金属铅,不易结合水分子而使吸附铅后材料表面结合水含量减少。
[Abstract]:Nanomaterials and their functionalized composites are widely used in adsorption research because their surfaces are rich in many functional groups. Adsorption of heavy metal contamination by different material structures and different surface groups, In this paper, engineering nanomaterials (zinc oxide, titanium dioxide, TIO _ 2, graphene oxide) and their composite materials (zinc oxide graphene oxide ZnO-GOO, zinc oxide / chitosan ZnO-CSO, ZnO-CSO) were prepared by means of the study of nano-materials (zinc oxide, TIO _ 2, Tio _ 2, graphene oxide) and their composites (zinc oxide, graphene oxide, ZnO-GOO, ZnO-CSO, ZnO-CSO). GO-CSN, TiO2-CSO _ 2) were characterized by SEM, FTIR (FTIR) and X-ray electron spectroscopy (XPS), and the kinetics of GO-CSO _ 2 and TiO2-CSO _ (2) were analyzed by SEM, FTIR (FTIR) and X-ray electron spectroscopy (XPS), respectively. The isothermal adsorption model was fitted to study the function of the functional groups on the surface of the materials in the process of adsorption of heavy metal lead and vanadium, and to discuss the difference between the adsorption of anion and anion. Based on the Lewis acid-base theory, a new type of high efficiency adsorption material was prepared. The main conclusions of this study are as follows: 1. The adsorption of lead and vanadium by ZnO-GOO-CSO-CSO-CSO-TiO2-CS and ZnO-GOO-TiO- TiO2-CS is in accordance with the second-order kinetic process R20.990.The isothermal fitting results accord with Langmuir and Freundlich models, and RL1 shows that the reaction is easy to proceed. The free energy of Gyibug is less than zero, and the adsorption reaction takes place spontaneously. 2. The metal oxide nanomaterials exhibit different adsorption properties because of their different structure. At pH 6.5, the surface of nanometer ZnO is positively charged, and the surface of nanometer TiO_2 is negative. The saturated adsorption amounts of lead and vanadium for nano-scale ZnO and TiO_2 were 192.64 ~ 49.90 mg 路g ~ (-1) and 433.13 ~ (13) ~ 369.10 mg 路g ~ (-1), respectively. The adsorption process of lead and vanadium was affected by physical and chemical factors, and the adsorption of lead and vanadium mainly occurred on the terminal hydroxyl group of nanomaterials. In the process of vanadium adsorption, it is easy to bind water molecules to form a water molecular network, while in the process of adsorption of lead, the ability to bind water molecules is relatively weak. 3. The surface properties of different materials can be changed by the binding of nano ZnO to different materials. As a result, the saturated adsorption capacity of lead and vanadium for the composite material. ZnO-go and ZnO-CS were 917.833396.50mg 路g-1 and 663.73n211.50mg 路g-1ZnO-GO respectively by hydrogen bonding, which resulted in the existence of Zn-OH and C-OH on the surface of the composite, and the decrease of the two hydroxyl groups after the adsorption of lead. The adsorbed water content of ZnO-CS increased after vanadium adsorption. The results of hydrogen bonding also showed that the adsorption of lead mainly occurred on Zn-OH, C-OH and C-O-C. However, the adsorption of vanadium mainly occurred on Zn-OH .4.Glutaraldehyde (linking hydroxyl and amino crosslinked CS with go and ZnO) was used to change the adsorbability of lead and vanadium. The saturated adsorption capacities of lead and vanadium for CS-TiO_2 and CS-GO were 32.88 ~ 86.75 mg 路g ~ (-1) and 18.52 ~ (2 +) ~ 56.73 mg 路g ~ (-1) for lead and vanadium, respectively. The adsorption of GO-OH on CS-hydroxyl group was mainly caused by the increase of the content of the terminal hydroxyl in TiO_2 in CS-TiO2 due to the opening of C-O-C, which was crosslinked with glutaraldehyde. Bridged hydroxyl groups do not participate in the adsorption of lead on C-O-C, C-OH and Ti-OH (terminal) by CS-TiO2, while vanadium adsorbs on -NH2. 5. in the XPSO1s peak, The binding water content changes before and after the adsorption of heavy metals. Vanadium V, a heavy metal in the form of anion containing oxygen, is used as Lewis acidic site O as Lewis basic site, and OH- and H in dissociated water can be adsorbed. It makes it easier for six materials to bind to water molecules and increase the content of bound water after adsorption of vanadium, while the heavy metal lead, which is mainly composed of cations, is not easy to bind to water molecules, thus reducing the content of bound water on the surface of the materials after adsorption of lead.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O647.3

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