改性三维氧化石墨烯材料的制备及其对铀（VI）吸附性能的研究

发布时间：2018-02-11 05:16

本文关键词： 三维氧化石墨烯铀吸附　出处：《东华理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：铀是核能的主要来源,也是最有毒的一种重金属。因此,从废水中去除和富集铀十分必要。近年来石墨烯基材料因其大的比表面积和对环境中的污染物表现出优良的吸附性能而受到广泛关注。其中三维石墨烯基材料又具有多孔和易于回收的优点,在吸附领域具有潜在的应用。本文以氧化石墨烯(GO)为前驱体,通过水热法和冷冻干燥法分别制备出具有三维立体结构的L-精氨酸(L-Arginine)改性氧化石墨烯海绵(L-Ar-GOS)、磺酸化杯[4]芳烃改性氧化石墨烯海绵(S-GOS)和二乙烯三胺五乙酸(DTPA)改性氧化石墨烯海绵(D-GOS)。采用SEM、XRD、FT-IR和XPS等分析手段对其进行分析,并探究其对铀(VI)的吸附性能,具体研究内容如下:(1)L-Ar-GOS具有交联的分层多孔结构,在水热过程中GO和L-Arginine发生了交联反应。L-Ar-GOS对铀(VI)的吸附受pH影响很大,但不受离子强度的影响,吸附的最佳pH为5.0;吸附平衡时间为9 h;吸附过程可用准二级动力学方程来描述,即其对铀(VI)的吸附受化学作用控制;吸附行为符合Langmuir吸附等温模型,单分子层吸附量为238.66 mg·g-1。吸附热力学函数值表明,铀(VI)的吸附是吸热的和自发的。吸附/解吸循环的实验结果表明,L-Ar-GOS具有较好的再生、可重复使用性。另外,L-Ar-GOS对铀的选择性优于GO。(2)S-GOS也同样具有三维互连分层多孔结构,在自主装形成三维石墨烯结构的过程中,磺酸化杯[4]芳烃起交联剂的作用。S-GOS对铀(VI)的吸附性能受溶液的初始pH值,吸附时间、铀初始浓度和离子强度等因素的影响。吸附铀(VI)的最佳pH为6.0,在180 min内即可达到吸附平衡。对铀(VI)的吸附更适合用准二级动力学和Langmuir等温模型来描述,吸附过程受化学作用主导,对铀(VI)的单层吸附容量为257.07 mg·g-1。另外,吸附热力学结果表明,S-GOS对铀(VI)的吸附是吸热和自发的过程。S-GOS具有良好的再生-可重复使用性,用1.0 mol·L-1HCl溶液可把大部分铀(VI)从中解吸出来,吸附/解吸循环五次后,对铀的吸附量仅下降13%。(3)D-GOS的结构同L-Ar-GOS和S-GOS有差异,它具有相对有序的三维层状结构。这可能是因为制备D-GOS时水热反应是在碱性条件下进行的。其对铀(VI)的吸附性能受溶液的初始pH值、吸附时间、铀初始浓度和温度等因素的影响,不受离子强度的影响。在pH=6时,其对铀(VI)的吸附量最大,为312.1 mg·g-1。吸附240 min即可达到吸附平衡。吸附动力学结果表明,准二级动力学方程能更准确地描述其对铀(VI)的吸附过程。吸附行为更符合Langmuir等温模型,D-GOS对铀(VI)的单层吸附量为418.4 mg·g-1,远高于GO(192.68 mg·g-1)。热力学研究表明,D-GOS对铀(VI)的吸附是吸热和自发的过程。另外,D-GOS具有良好的再生和可重复使用性。
[Abstract]:Uranium is the main source of nuclear energy and the most toxic heavy metal. It is necessary to remove and enrich uranium from waste water. In recent years, graphene based materials have attracted much attention due to their large specific surface area and excellent adsorption performance to pollutants in the environment. Have the advantage of porous and easy to recycle, In this paper, graphene oxide is used as the precursor. The modified graphene oxide sponge L-Ar-GOS, modified by calix sulfonic acid [4] arene, and diethyltriamine pentaacetic acid (DTPA) modified oxygen were prepared by hydrothermal method and freeze-drying method, respectively. The modified graphene oxide sponge L-Ar-GOS was modified by L-Arginine, and the modified graphene sponge S-GOS by calix [4] arene sulfonic acid and DTPA modified by diethyltriamine pentaacetic acid were prepared, respectively. Graphene sponges were analyzed by means of SEMX XRDX FT-IR and XPS. The adsorption properties of Vi for uranium were also investigated. The main contents are as follows: (1) the L-Ar-GOS has cross-linked layered porous structure. During hydrothermal process, the adsorption of uranium Vi by go and L-Arginine is greatly affected by pH, but not by ionic strength. The optimum pH of adsorption is 5.0, the adsorption equilibrium time is 9 h, the adsorption process can be described by quasi-second-order kinetic equation, that is, the adsorption of uranium Vi is controlled by chemical interaction, and the adsorption behavior accords with the Langmuir adsorption isotherm model. The adsorption capacity of monolayer is 238.66 mg 路g-1.The thermodynamic function of adsorption shows that the adsorption of uranium Vi is endothermic and spontaneous. The experimental results of adsorption / desorption cycle show that L-Ar-GOS has good regeneration. Moreover, the selectivity of L-Ar-GOS to uranium is superior to that of GO.(2)S-GOS, and it also has a three-dimensional interconnect layered porous structure. The adsorption properties of calix [4] arene sulfonic acid acting as crosslinker. S-GOS for uranium Vi are determined by the initial pH value of the solution and the adsorption time. The optimum pH of the adsorbed uranium Vi is 6.0, and the adsorption equilibrium can be reached within 180 min. The adsorption of Vi) is more suitable to be described by quasi-second-order kinetics and Langmuir isothermal model. The adsorption process is dominated by chemical action, and the adsorption capacity of the monolayer of uranium Vi is 257.07 mg 路g ~ (-1). In addition, the adsorption thermodynamic results show that the adsorption of uranium Vi by S-GOS is an endothermic and spontaneous process. S-GOS has a good regeneration and reusability, and the adsorption capacity of the monolayer is 257.07 mg 路g ~ (-1). Most of uranium can be desorbed with 1.0 mol 路L ~ (-1) HCl solution. After five cycles of adsorption / desorption, the adsorption capacity of uranium decreased by only 13%. The structure of D-GOS is different from that of L-Ar-GOS and S-GOS. It has a relatively ordered three-dimensional layered structure. This may be due to the hydrothermal reaction in the preparation of D-GOS under alkaline conditions. Its adsorption performance for uranium ion VI is determined by the initial pH value of the solution and the adsorption time. The initial concentration and temperature of uranium are not affected by the ionic strength. At pH = 6:00, the adsorption capacity of Vi is 312.1 mg 路g-1.The adsorption equilibrium can be reached at 240 min. The quasi-second-order kinetic equation can more accurately describe the adsorption process of uranium Vi, and the adsorption behavior is more in line with the Langmuir isothermal model (D-GOS), the monolayer adsorption capacity of Vi is 418.4 mg 路g-1, which is much higher than that of GO(192.68 mg 路g-1.The thermodynamic study shows that the adsorption of Vi to uranium by D-GOS is as follows: 1. Endothermic and spontaneous processes. In addition, D-GOS has good regeneration and reusability.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O647.3

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